Judgment of 16 December 2015

Document Number
152-20151216-JUD-01-00-EN
Document Type
Date of the Document
Document File
Bilingual Document File

COUR INTERNATIONALE DE JUSTICE

RECUEIL DES ARRÊTS,
AVIS CONSULTATIFS ET ORDONNANCES

CERTAINES ACTIVITÉS MENÉES PAR LE NICARAGUA
DANS LA RÉGION FRONTALIÈRE

(COSTA RICA c. NICARAGUA)

et

CONSTRUCTION D’UNE ROUTE AU COSTA RICA

LE LONG DU FLEUVE SAN JUAN

(NICARAGUA c. COSTA RICA)

ARRÊT DU 16 DÉCEMBRE 2015

2015

INTERNATIONAL COURT OF JUSTICE

REPORTS OF JUDGMENTS,
ADVISORY OPINIONS AND ORDERS

CERTAIN ACTIVITIES CARRIED OUT BY NICARAGUA
IN THE BORDER AREA

(COSTA RICA v. NICARAGUA)

and

CONSTRUCTION OF A ROAD IN COSTA RICA

ALONG THE SAN JUAN RIVER

(NICARAGUA v. COSTA RICA)

JUDGMENT OF 16 DECEMBER 2015

5 Ord 1088.indb 1 19/10/16 12:01 Mode officiel de citation :

Certaines activités menées par le Nicaragua dans la région fron▯talière
(Costa Rica c. Nicaragua) et Construction d’une route au Costa Rica
le long du fleuve San Juan (Nicaragua c. Costa Rica),
arrêt, C.I.J. Recueil 2015, p. 665

Officialitation:

Certain Activities Carried Out by Nicaragua in the Border Area
(Costa Rica v. Nicaragua) and Construction of a Road in Costa Rica
along the San Juan River (Nicaragua v. Costa Rica),
Judgment, I.C.J. Reports 2015, p. 665

o
N de vente:
ISSN 0074-4441 Sales number 1088
ISBN 978-92-1-157280-3

5 Ord 1088.indb 2 19/10/16 12:01 16 DÉCEMBRE 2015

ARRÊT

CERTAINES ACTIVITÉS MENÉES PAR LE NICARAGUA
DANS LA RÉGION FRONTALIÈRE

(COSTA RICA c. NICARAGUA)

et

CONSTRUCTION D’UNE ROUTE AU COSTA RICA

LE LONG DU FLEUVE SAN JUAN

(NICARAGUA c. COSTA RICA)

CERTAIN ACTIVITIES CARRIED OUT BY NICARAGUA
IN THE BORDER AREA

(COSTA RICA v. NICARAGUA)

and

CONSTRUCTION OF A ROAD IN COSTA RICA
ALONG THE SAN JUAN RIVER

(NICARAGUA v . COSTA RICA)

16 DECEMBER 2015

JUDGMENT

5 Ord 1088.indb 3 19/10/16 12:01 665

TABLE OF CONTENTS

Paragraphs

Chronology of the Procedfure 1-52

I. Jurisdiction of the Coufrt 54 -55

II. Geographical and Historical Context and Origin of the

Disputes 56-64

III. Issues in the osta RiCav. NiCaRagua Case 65-144
A. Sovereignty over the disputed territory and allegedreaches

thereof 65 -99
B. Alleged violations of international environmental law 100 -120

1. Procedural obligations 101 -112

(a) The alleged breach of the obligation to carry out an
environmental impact assessment 101 -105

(b) The alleged breach of an obligation to notify and
consult 106 -111

(c) Conclusion 112
2. Substantive obligations concerning transboundary

harm 113-120
C. Compliance with provisional measures 121 -129

D. Rights of navigation 130 -136
E. Reparation 137 -144

IV. Issues in theN iCaRagua v.C osta RiCaCase 145-228

A. The alleged breach of procedural obligations 146 -173

1. The alleged breach of the obligation to carry out an
environmental impact assessment 146 -162
2. The alleged breach of Article 14 of the Convention on Bio

logical Diversity 163-164
3. The alleged breach of an obligation to notify and

consult 165-172
B. Alleged breaches of substantive obligations 174 -223

1. The alleged breach of the obligation not to cause sign-fi
cant transboundary harm to Nicaragua 177-217

(a) The contribution of sediment from the road to the
river 181-186
(b) Whether the road -derived sediment caused significant

harm to Nicaragua 187-216

4

5 Ord 1088.indb 5 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 666

(i) Alleged harm caused by increased sediment
concentrations in the river 188-196
(ii) Alleged harm to the river’s morphology, to

navigation and to Nicaragua’s dredging pro -
gramme 197-207
(iii) Alleged harm to water quality and the aquatic

ecosystem 208 -213
(iv) Other alleged harm 214-216

(c) Conclusion 217
2. Alleged breaches of treaty obligations 218 -220

3. The obligation to respect Nicaragua’s territorial integrity
and sovereignty over the San Juan River 221-223

C. Reparation 224 -228

Operative Clause 229

5

5 Ord 1088.indb 7 19/10/16 12:01 667

INTERNATIONAL COURT OF JUSTICE

YEAR 2015 2015

16 December
16 December 2015 General List
Nos.150 and 152

CERTAIN ACTIVITIES CARRIED OUT BY NICARAGUA

IN THE BORDER AREA

(COSTA RICA v. NICARAGUA)

AND

CONSTRUCTION OF A ROAD IN COSTA RICA

ALONG THE SAN JUAN RIVER

(NICARAGUA v. COSTA RICA)

Jurisdiction of the Court.

* *

Geographical and historical context and origin of the disputes.
The San Juan River, Lower San Juan and Colorado —iIsla Calero and
Isla Portillos — Harbor Head La—oWetlands of international impo—tance

1858Treaty of LimitsCleveland Award— Alexander Awards — Dredging of
the San Juan by Nicaragua Activities of Nicaragua in the northern part of
Isla Portillos:dging of a channel (caño) and establishment of a military pres
ence— Construction of Route 1856 Juan Rafael Mora Porras (the road) by ▯
Costa Rica.

* *

Issues in the Costa Rica v. Nicaragua case.
Sovereignty over the disputed territory — Definition of “disputed territory” —
Description of boundary in 1Treaty,leveland and Alexander Award—

ArticlesI and VI of 1858 Treaty to be read together — Sovereignty over right
bank of San Juan River as far as its mouth attributed to Costa Rica — Reference
to “first channel met” in first Alexande— Satellite and aerial images

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insufficient to prove caño existed prior to dredging in 2010 — Affidavits of Nica‑
raguan State officials also insufficientgnificance of map evidence and effec-
tivités limited Effectivités cannot affect title to sovereignty resulting from
1858 Treaty and Cleveland and Alexander Awards — Existence of caño prior to
2010 contradicted by other evidence — Nicaragua’s claim would prevent

Costa Rica from enjoying territorial sovereignty over the right bank of the Sa▯n
Juan as far as its mouth — Right bank of the caño not part of the boundary—
Sovereignty over disputed territory belongs to Costa Rica.

Alleged breaches of Costa Rica’s sovereignty — Uncontested that Nicaragua
excavated three caños and established a military presence in disputed territory —
Costa Rica’s territorial sovereignty breached — Obligation to make reparation —
No violation of Article IX of 1858 Treaty — No need to consider possible violation
of prohibition of threat or use of force — No need to consider whether conduct of

Nicaragua constitutes a military occupation.

*

Alleged violations of international environmental law.
Procedural obligations — Obligation to conduct environmental impact assess ‑
ment concerning activities that risk causing significant transboundary h▯arm

Content of environmental impact assessment depends on specific circumsta▯nces —
If assessment confirms risk of significant transboundary harm, State pla▯nning the
activity is required, in conformity with due diligence obligation, to no▯tify and
consult with potentially affected State, where necessary to determine ap▯propriate
measures to prevent or mitigate risk — Nicaragua’s dredging programme did not

give rise to risk of significant transboundary ha—m Nicaragua not required to
carry out transboundary environmental impact assessment — No obligation under
general international law to notify and consult since no risk of signifi▯cant trans
boundary harm — No conventional obligation to notify and consult in present
case — Court concludes that no procedural obligations breached by Nicaragu▯a.

Substantive obligations — Specific obligations concerning San Juan River in
1858 Treaty as interpreted by Cleveland Award — Customary law obligation to

exercise due diligence to avoid causing significant transboundary harm — No need
to discuss relationship between these obligations because no harm establ▯i—hed
No proof that dredging of Lower San Juan harmed Costa Rican wetland — Not
shown that dredging programme caused significant reduction in flow of Co▯lorado
River — Any diversion of water due to dredging did not seriously impair nav▯iga
tion on Colorado River or otherwise cause harm to Costaica — Court concludes

that no substantive obligations breached by Nicaragua.

*

7

5 Ord 1088.indb 11 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 669

Compliance with provisional measures — Nicaragua breached its obligations
under Order of 8 March 2011 by excavating two caños and establishing a military
presence in disputed territory in 2013 — Breach of obligations under Court’s
Order of 22 November 2013 not established.

*

Rights of navigation — Claim is admissible — Article VI of the 1858 Treaty —
Court’s Judgment in Dispute regarding Navigational and Related Rights — No

need for the Court to interpret Nicaraguan Decree No. 079‑2009 — Five instances
of violations of navigational rights raised by Costa Rica — Two of the five
instances examined — Court concludes Nicaragua breached Costa Rica’s naviga ‑
tional rights pursuant to the 1858Treaty — Not necessary for Court to consider
the other incidents invoked by Costa Rica.

*

Reparation — Requests to order repeal of Decree No. 079‑2009 and cessation
of dredging activities cannot be granted— Declaration of breach provides ade ‑
quate satisfaction for non‑material injury suffered No need for guarantees of
non‑repetition — Costa Rica entitled to compensation for material damage —

Parties should engage in negotiation on amount of compensation — Failing agree‑
ment within 12 months, Court will determine amount at request of one of the Par ‑
ties— Award of costs under Article 64 of the Statute not appropriate.

* *

Issues in the Nicaragua v. Costa Rica case.

Procedural obligations.
Alleged breach of obligation to carry out environmental impact assessment—
Due diligence obligation requires State to ascertain whether a proposed activity
entails risk of significant transboundary harm — Environmental impact▯ assess ‑
ment required when risk is present — No evidence that Costa Rica determined
whether environmental impact assessment was necessary prior to construct▯ing the

road — Large scale of road project — Proximity to San Juan River on Nicara ‑
guan territory — Risk of erosion due to deforestation — Possibility of natural
disasters in area — Presence of two wetlands of international importance in
area — Construction of road carried a risk of significant transboundary ha▯r—
No emergency justifying immediate construction of road — Court need not decide

whether there is, in international law, an emergency exemption from obli▯gation to
carry out environmental impact assessment — Costa Rica under obligation to con
duct environmental impact assessment — Obligation requires ex ante evaluation of
risk of significant transboundary harm — Environmental Diagnostic Assessment
and other studies by Costa Rica were post hoc assessments — Costa Rica has not

complied with obligation to carry out environmental impact assessment.

8

5 Ord 1088.indb 13 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 670

Alleged breach of Article 14 of Convention on Biological Diversity — No viola‑
tion established.
Alleged breach of obligation to notify and consult — General international law
duty to notify and consult does not call for examination because Costa Rica has
not carried out environmental impact assessment — 1858 Treaty did not impose
obligation on Costa Rica to notify Nicaragua of construction of road — No proce‑
dural obligations arose under Ramsar Convention.

*

Substantive obligations.
Alleged breach of obligation to exercise due diligence to prevent causin▯g signifi ‑
cant transboundary harm — Modelling and estimates by experts suggest sediment
due to construction of road amounts to at most 2 per cent of San Juan River’s total
load — Actual measurements provided to Court do not indicate that road signifi ‑

cantly impacted sediment levels in river — Increase in sediment levels as a result of
construction of road did not in and of itself cause significant transbou▯ndary
harm — No significant harm to river’s morphology, to navigation or to N▯icara ‑
gua’s dredging programme established — No proof of significant harm to river’s
ecosystem or water quality — Arguments concerning other alleged harm fail.

Alleged breaches of treaty obligations— No violation established.

Claim concerning violation of territorial integrity and sovereignty No viola‑
tion established.

*

Reparation — Declaration of wrongful conduct in respect of obligation to

conduct environmental impact assessment is the appropriate measure of sa▯tis ‑
faction — No grounds to order Costa Rica to cease continuing wrongful acts —
Restitution and compensation not appropriate remedies in absence of sign▯ificant
harm — No need to appoint expert or committee to evaluate harm — Nicaragua’s
request to order Costa Rica not to undertake future development without an envi ‑
ronmental impact assessment dismissed.

JUDGMENT

Present: President Abraham ; Vice‑President Yusuf ; Judges Owada, Tomka,
Bennouna, Cançado Trindfade, Greenwood, Xue, Donofghue,
Gaja, Sebutinde, Bhandarfi, Robinson, Gevorgian ; Judges ad hoc
Guillaume, Dugard; Registrar Couvreur.

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In the case concerning Certain Activities Carried Out by Nicaragua in the Bor ‑
der Area, and in the joined case (see paragraph 19 below) concerning Construc‑
tion of a Road in Costa Rica along the San Juan River,

between

the Republic of Costa Rica,

represented by
H.E. Mr. Manuel A. González Sanz, Minister for Foreign Affairs and Wor -
ship of Costa Rica;

H.E. Mr. Edgar Ugalde Alvarez, Ambassador on Special Mission,

as Agent;
H.E. Mr. Sergio Ugalde, Ambassador of Costa Rica to the Kingdom of the
Netherlands, member of the Permanent Court of Arbitration,

as Co-Agent, Counsel and Advocate ;

Mr. Marcelo Kohen, Professor of International Law at the Graduate Insti -
tute of International and Development Studies, Geneva, member of the
Institut de droit international,
Mr. Samuel Wordsworth, Q.C., member of the English Bar, member of the
Paris Bar, Essex Court Chambers,

Mr. Arnoldo Brenes, Senior Adviser to the Ministry of Foreign Affairs and
Worship of Costa Rica, member of the Costa Rican Bar,
Ms Kate Parlett, Solicitor admitted in Queensland, Australia, and in Englanfd
and Wales,
Ms Katherine Del Mar, member of the English Bar, 4 New Square, Lincoln’sf

Inn,
as Counsel and Advocates ;

Mr. Simon Olleson, member of the English Bar, 13 Old Square Chambers,
as Counsel;

Mr. Ricardo Otárola, Adviser to the Ministry of Foreign Affairs and Wor -
ship of Costa Rica,
Ms Shara Duncan, Adviser to the Ministry of Foreign Affairs and Worship

of Costa Rica,
Mr. Gustavo Campos, Minister Counsellor and Consul General of CostaRica
to the Kingdom of the Netherlands,
Mr. Rafael Sáenz, Minister Counsellor at the Costa Rican Embassy in the
Kingdom of the Netherlands,

Ms Ana Patricia Villalobos, Official at the Ministry of Foreign Affairs anfd
Worship of Costa Rica,
as Assistant Counsel ;

Ms Elisa Rivero, Administrative Assistant at the Ministry of Foreign Affairfs
and Worship of Costa Rica,

as Assistant,

and

the Republic of Nicaragua,
represented by

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5 Ord 1088.indb 17 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 672

H.E. Mr. Carlos José Argüello Gómez, Ambassador of Nicaragua to the
Kingdom of the Netherlands,
as Agent and Counsel ;

Mr. Stephen C. McCaffrey, Professor of International Law at the University
of the Pacific, McGeorge School of Law, Sacramento, former member and
former Chair of the International Law Commission,

Mr. Alain Pellet, Professor at the University Paris Ouest, Nanterr-eLa Défense,
former member and former Chair of the International Law Commission,
member of the Institut de droit international,
Mr. Paul S. Reichler, Attorney-at-Law, Foley Hoag LLP, member of the

Bars of the United States Supreme Court and the District of Columbia,
Mr. Andrew B. Loewenstein, Attorney-at-Law, Foley Hoag LLP, member of
the Bar of the Commonwealth of Massachusetts,

as Counsel and Advocates ;
Mr. César Vega Masís, Deputy Minister for Foreign Affairs, Director off
Juridical Affairs, Sovereignty and Territory, Ministry of Foreign Affairs of

Nicaragua,
Mr. Walner Molina Pérez, Juridical Adviser, Ministry of Foreign Affairs off
Nicaragua,
Mr. Julio César Saborio, Juridical Adviser, Ministry of Foreign Affairs off
Nicaragua,

as Counsel;

Mr. Edgardo Sobenes Obregon, Counsellor, Embassy of Nicaragua in the
Kingdom of the Netherlands,
Ms Claudia Loza Obregon, First Secretary, Embassy of Nicaragua in the
Kingdom of the Netherlands,
Mr. Benjamin Samson, Researcher, Centre de droit international de Nanterre

(CEDIN), University of Paris Ouest, Nanterre -La Défense,
Ms Cicely O. Parseghian, Attorney-at-Law, Foley Hoag LLP, member of the
Bar of the Commonwealth of Massachusetts,
Mr. Benjamin K. Guthrie, Attorney -at-Law, Foley Hoag LLP, member of
the Bar of the Commonwealth of Massachusetts,

Mr. Ofilio J. Mayorga, Attorney-at-Law, Foley Hoag LLP, member of the
Bars of the Republic of Nicaragua and New York,
as Assistant Counsel ;

Mr. Danny K. Hagans, Principal Earth Scientist at Pacific Watershed Associ-
ates, Inc.,
Mr. Robin Cleverly, Geographical and Technical Consultant,

Ms Blanca P. Ríos Touma, Ph.D., Assistant Professor at Universidad Tec -
nológica Indoamérica in Quito, Ecuador,
Mr. Scott P. Walls, Master of Landscape Architecture — Environmental
Planning, Sole Proprietor and Fluvial Geomorphologist at Scott Walls
Consulting, Ecohydrologist at cbec ecoengineering, Inc., and Chief Finanf

cial Officer and Project Manager at International Watershed Partners,

Ms Victoria Leader, Geographical and Technical Consultant,

as Scientific Advisers and Experts,

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5 Ord 1088.indb 19 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 673

The Court,

composed as above,
after deliberation,

delivers the following Judgment :

1. By an Application filed in the Registry of the Court on 18 November 2010,
the Republic of Costa Rica (hereinafter “Costa Rica”) instituted proceedings

against the Republic of Nicaragua (hereinafter “Nicaragua”) in tfhe case con -
cerning Certain Activities Carried Out by Nicaragua in the Border Area
(Costa Rica v. Nicaragua) (hereinafter referred to as the “Costa Rica v. Nicara‑
gua case”). In that Application, Costa Rica alleges in particular that Nicaragua
invaded and occupied Costa Rican territory, and that it dug a channel thereon ;

it further reproaches Nicaragua with conducting works (notably dredgingf of the
San Juan River) in violation of its international obligations.
2. In its Application, Costa Rica invokes as a basis of the jurisdiction of the
Court Article XXXI of the American Treaty on Pacific Settlement adopted at

Bogotá on 30 April 1948 (hereinafter the “Pact of Bogotá”). In addition,
Costa Rica seeks to found the jurisdiction of the Court on the declaration it
made on 20 February 1973 under Article 36, paragraph 2, of the Statute,
as well as on the declaration which Nicaragua made on 24 September 1929 (and
amended on 23 October 2001) under Article 36 of the Statute of the Permanent

Court of International Justice and which is deemed, pursuant to Article 36,
paragraph 5, of the Statute of the present Court, for the period which it still has
to run, to be acceptance of the compulsory jurisdiction of this Court.
3. On 18 November 2010, having filed its Application, Costa Rica also sub-

mitted a request for the indication of provisional measures, pursuant to Arti -
cle 41 of the Statute and Articles 73, 74 and 75 of the Rules of Court.
4. In accordance with Article 40, paragraph 2, of the Statute, the Registrar
communicated a signed copy of the Application forthwith to the Governmenft of

Nicaragua ; and, under paragraph 3 of that Article, all States entitled to appear
before the Court were notified of the filing of the Application.
5. Pursuant to the instructions of the Court under Article 43 of the Rules of
Court, the Registrar addressed to States parties to the Convention on Weftlands
of International Importance especially as Waterfowl Habitat, signed at Rfamsar

on 2 February 1971 (hereinafter the “Ramsar Convention”), the notification
provided for in Article 63, paragraph 1, of the Statute.
6. Since the Court included no judge of the nationality of the Parties uponf
the Bench, each of them, in exercise of the right conferred by Article 31, para -

graph 3, of the Statute, chose a judge ad hoc in the case. Costa Rica chose
Mr. John Dugard and Nicaragua chose Mr. Gilbert Guillaume.
7. By an Order of 8 March 2011 (hereinafter the “Order of 8 March 2011”),
the Court, having heard the Parties, indicated provisional measures addrfessed to

both Parties. The Court also directed each Party to inform it about compfliance
with the provisional measures. By various communications, the Parties eafch
notified the Court of the measures they had taken with reference to the fafore -
mentioned Order and made observations on the compliance by the other Parfty
with the said Order.

8. By an Order of 5 April 2011, the Court fixed 5 December 2011 and
6 August 2012 as the respective time -limits for the filing in the case of a Memo -

12

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rial by Costa Rica and a Counter -Memorial by Nicaragua. The Memorial and
the Counter-Memorial were filed within the time -limits thus prescribed.

9. By an Application filed in the Registry on 22 December 2011, Nicaragua

instituted proceedings against Costa Rica in the case concerning Construction of
a Road in Costa Rica along the San Juan River (Nicaragua v. Costa Rica) (here-
inafter referred to as the “Nicaragua v. Costa Rica case”). In that Application,
Nicaragua stated that the case related to “violations of Nicaraguan sfovereignty
and major environmental damages on its territory”, contending, in parfticular,

that Costa Rica was carrying out major road construction works in the border
area between the two countries along the San Juan River, in violation off several
international obligations and with grave environmental consequences.

10. In its Application, Nicaragua invokes Article XXXI of the Pact of Bogotá

as a basis for the jurisdiction of the Court. In addition, Nicaragua seefks to
found the jurisdiction of the Court on the aforementioned declarations afccept -
ing the jurisdiction of the Court (see paragraph 2 above).
11. In accordance with Article 40, paragraph 2, of the Statute, the Registrar
communicated a signed copy of the Application forthwith to the Governmenft of

Costa Rica ; and, under paragraph 3 of that Article, all States entitled to appear
before the Court were notified of the filing of the Application.
12. Pursuant to the instructions of the Court under Article 43 of its Rules,
the Registrar addressed the notifications provided for in Article 63, paragraph 1,
of the Statute, to States parties to the Ramsar Convention, to the 1992 fConven -

tion on Biological Diversity and to the 1992 Convention for the Conservation
of the Biodiversity and Protection of Priority Wilderness Areas in Central f
America.
13. Since the Court included no judge of the nationality of the Parties uponf

the Bench, each of them, in exercise of the right conferred by Article 31, para-
graph 3, of the Statute, chose a judge ad hoc in the case. Nicaragua chose
Mr. Gilbert Guillaume and Costa Rica chose Mr. Bruno Simma.
14. By an Order of 23 January 2012, the Court fixed 19 December 2012 and
19 December 2013 as the respective time -limits for the filing of a Memorial by
Nicaragua and a Counter -Memorial by Costa Rica. The Memorial and the

Counter-Memorial were filed within the time -limits thus prescribed.
15. In the Counter -Memorial it filed in the Costa Rica v. Nicaragua case on
6 August 2012, Nicaragua submitted four counter -claims. In its first counter -
claim, it requested the Court to declare that “Costa Rica bears responsibility to
Nicaragua” for “the impairment and possible destruction of navigatfion on the

San Juan River caused by the construction of [the] road”. In its secofnd
counter-claim, it asked the Court to declare that it “has become the sole
sovereign over the area formerly occupied by the Bay of San Juan del Norfte”.
In its third counter -claim, it requested the Court to find that “Nicaragua
has a right to free navigation on the Colorado . . . until the conditions of navig-

ability existing at the time the 1858 Treaty [of Limits] was concluded are
re-established”. Finally, in its fourth counter -claim, Nicaragua alleged that
Costa Rica violated the provisional measures indicated by the Court in its
Order of 8 March 2011.

16. At a meeting held by the President with the representatives of the Partifes
on 19 September 2012, the Parties agreed not to request the Court’s authorifza -
tion to file a Reply and a Rejoinder in the Costa Rica v. Nicaragua case. At the

13

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same meeting, the Co -Agent of Costa Rica raised certain objections to the
admissibility of the first three counter-claims contained in the Counter-emorial
of Nicaragua. He confirmed these objections in a letter of the same day.f

By letters dated 28 September 2012, the Registrar informed the Parties that

the Court had fixed 30 November 2012 and 30 January 2013 as the respective
time-limits for the filing of written observations by Costa Rica and Nicaragua
on the admissibility of the latter’s first three counter -claims. Both Parties filed
their observations within the time-limits thus prescribed.

17. By letters dated 19 December 2012, which accompanied its Memorial in
the Nicaragua v. Costa Rica case, Nicaragua requested the Court to “decide
proprio motu whether the circumstances of the case require[d] the indication of
provisional measures” and to consider whether there was a need to joifn the

proceedings in the Nicaragua v. Costa Rica and Costa Rica v. Nicaragua cases.

By a letter dated 15January 2013, the Registrar, acting on the instructions of
the President, asked Costa Rica to inform the Court, by 18 February 2013 at the
latest, of its views on both questions. Costa Rica communicated its views within

the time-limit thus prescribed.
18. By letters dated 11 March 2013, the Registrar informed the Parties that
the Court was of the view that the circumstances of the Nicaragua v. Costa Rica
case, as they presented themselves to it at that time, were not such as fto require
the exercise of its power under Article 75 of the Rules of Court to indicate pro -

visional measures proprio motu.
19. By two separate Orders dated 17 April 2013, the Court joined the pro -
ceedings in the Costa Rica v. Nicaragua and Nicaragua v. Costa Rica cases.
20. By a communication of the same date, Mr. Simma, who had been chosen

by Costa Rica to sit as judge ad hoc in the Nicaragua v. Costa Rica case,
informed the Court of his decision to resign from his functions, followifng
the above-mentioned joinder of proceedings. Thereafter, Judges Guillaume
and Dugard sat as judges ad hoc in the joined cases (see paragraphs 6 and 13
above).

21. By an Order of 18 April 2013, the Court ruled on the admissibility of
Nicaragua’s counter-claims in the Costa Rica v. Nicaragua case. It concluded
that there was no need for it to adjudicate on the admissibility of Nicafragua’s
first counter-claim as such. It found the second and third counter -claims inad -
missible as such. The Court also found that there was no need for it to fentertain

the fourth counter -claim as such, and that the Parties might take up any ques -
tion relating to the implementation of the provisional measures indicatefd by the
Court in its Order of 8 March 2011 in the further course of the proceedings.

22. On 23 May 2013, Costa Rica, with reference to Article 41 of the Statute
and Article 76 of the Rules of Court, filed with the Registry a request for the
modification of the Order indicating provisional measures made on 8 March
2011. In its written observations thereon, dated 14 June 2013, Nicaragua asked
the Court to reject Costa Rica’s request, while in its turn requesting the Court

to otherwise modify the Order of 8 March 2011 on the basis of Article 76 of the
Rules of Court. Costa Rica communicated to the Court its written observations
on Nicaragua’s request on 20 June 2013.

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23. By an Order of 16 July 2013, the Court found that “the circumstances, as
they now present themselves to the Court, are not such as to require thef exercise
of its power to modify the measures indicated in the Order of 8 March 2011”.
The Court however reaffirmed the said provisional measures.

24. On 24 September 2013, Costa Rica, with reference to Article 41 of the
Statute and Articles 73, 74 and 75 of the Rules of Court, filed with the Registry
a request for the indication of new provisional measures in the Costa Rica v.
Nicaragua case.
25. On 11 October 2013, Nicaragua filed with the Registry a request for the

indication of provisional measures in the Nicaragua v. Costa Rica case. Nicara -
gua suggested that its request be heard concurrently with Costa Rica’s request
for the indication of new provisional measures in the Costa Rica v. Nicaragua
case, at a single set of oral proceedings. By letter of 14 October 2013, Costa Rica
objected to Nicaragua’s suggestion. By letters dated 14 October 2013, the

Registrar informed the Parties that the Court had decided that it would fconsider
the two requests separately.
26. By an Order of 22 November 2013 rendered in the Costa Rica v. Nicara ‑
gua case, the Court, having heard the Parties, reaffirmed the provisional f
measures indicated in its Order of 8 March 2011 and indicated new provisional

measures addressed to both Parties. The Court also directed each Party tfo inform
it, at three-month intervals, as to compliance with the provisional measures. By
various communications, each of the Parties notified the Court of the mefasures
they had taken with reference to the aforementioned Order and made observa -
tions on the compliance by the other Party with the said Order.

27. By an Order of 13December 2013 rendered in the Nicaraguav. Costa Rica
case, the Court, after hearing the Parties, found “that the circumstafnces, as they
now present themselves to the Court, are not such as to require the exerfcise of

its power under Article 41 of the Statute to indicate provisional measures”.

28. At a meeting held by the President with the representatives of the Partifes
on 22 January 2014, Nicaragua requested the Court to authorize a second round f
of written pleadings in the Nicaragua v. Costa Rica case, while Costa Rica
objected. By an Order of 3 February 2014, the Court authorized the submission

of a Reply by Nicaragua and a Rejoinder by Costa Rica, and fixed 4 August
2014 and 2 February 2015 as the respective time -limits for the filing of those
pleadings. The Reply of Nicaragua and the Rejoinder of Costa Rica were duly
filed within the time-limits so prescribed.

29. By letters dated 2 April 2014, the Registrar informed the Parties that the
Court, in accordance with Article 54, paragraph 1, of the Rules of Court, had
fixed 3 March 2015 as the date for the opening of the oral proceedings in the
joined cases.
30. In a letter dated 4August 2014, which accompanied its Reply in the Nica ‑

ragua v. Costa Rica case, Nicaragua suggested that the Court appoint “a neutral
expert on the basis of Articles 66 and 67 of the Rules”. By letter of 14 August
2014, Costa Rica indicated that it was of the view “that there [was] no basis forf
the Court to exercise its power to appoint an expert as requested by Nicaragua”.
31. By a letter dated 15 October 2014, Nicaragua requested that the opening

of the oral proceedings in the joined cases be postponed until May 2015.f On the
basis that Costa Rica had stated, in its letter of 14 August 2014 referred to in the
previous paragraph, that the evidence submitted by the Parties “w[oulfd] be sup -

15

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plemented and completed” in Costa Rica’s Rejoinder in the Nicaragua v.
Costa Rica case, Nicaragua expressed the view that it would be “inadequate and f
inequitable for [it] to have less than one month to analyze and respond to
Costa Rica’s new scientific information and expert reports”. By letter off 20Octo -

ber 2014, Costa Rica opposed this request, arguing in particular that any delay
in the Court hearing and adjudging the Costa Rica v. Nicaragua case would
prejudice Costa Rica, that Nicaragua had sufficient time to analyse the Rejoin -
der and formulate its response before the commencement of the hearings, f
and that Nicaragua’s request was belated. By letters dated 17 November 2014,

the Registrar informed the Parties that the Court had decided to postponfe
the date for the opening of the oral proceedings in the joined cases until 1f4April
2015.
32. By letters dated 5December 2014, referring to the communications men -
tioned in paragraph 30 above, the Registrar informed the Parties that the Court

would find it useful if, during the course of the hearings in the two cafses, they could
call the experts whose reports were annexed to the written pleadings, in particular
Mr. Thorne and Mr. Kondolf. The Registrar also indicated that the Court would
be grateful if, by 15January 2015 at the latest, the Parties would make suggestions
regarding the modalities of the examination of those experts. Such suggefstions

were received from Nicaragua within the time -limit indicated. By a letter dated
20 January 2015, CostaRica commented on the suggestions of Nicaragua.
33. In a letter dated 2February 2015, which accompanied its Rejoinder in the
Nicaragua v. Costa Rica case, Costa Rica raised the possibility of a site visit to
the “location of the Road”. By a letter dated 10 February 2015, Nicaragua

expressed its willingness to assist to the fullest possible extent in thfe organiza
tion “of such a visit at the location of the road and the San Juan def Nicaragua
River”. It also reiterated its proposal that the Court appoint an expfert (see par-
graph 30 above) to assess the construction of the road, and suggested that thfe

expert be included in the Court’s delegation for any site visit. By af letter dated
11 February 2015, Costa Rica commented on Nicaragua’s letter of 10 February
2015, stating in particular that the appointment of an expert by the Court was
unnecessary. By letters dated 25 February 2015, the Registrar informed the Par -
ties that the Court had decided not to carry out a site visit.

34. By letters of the Registrar dated 4 February 2015, the Parties were
informed that they should indicate to the Court, by 2 March 2015 at the latest,
the names of the experts they intended to call, and communicate the othefr infor -
mation required by Article 57 of the Rules of Court. The Parties were also
instructed to provide the Court, by 16 March 2015 at the latest, with written

statements of these experts (limited to a summary of the expert’s owfn reports or
to observations on other expert reports in the case file), and were infformed that
these would replace the examination -in-chief. In addition, the Court invited the
Parties to come to an agreement as to the allocation of time for the crofss-exam -
ination and re -examination of experts by 16 March 2015 at the latest.

By the same letters, the Registrar also notified the Parties of the follfowing
details regarding the procedure for examining the experts. After having made
the solemn declaration required under Article 64 of the Rules of Court, the
expert would be asked by the Party calling him to endorse his written stfatement.
The other Party would then have an opportunity for cross -examination on the

contents of the expert’s written statement or his earlier reports. Ref-examination
would thereafter be limited to subjects raised in cross -examination. Finally, the
judges would have an opportunity to put questions to the expert.

16

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35. By letters dated 2 March 2015, the Parties indicated the names of the
experts they wished to call at the hearings, and provided the other infofrmation
concerning them required by Article 57 of the Rules of Court (see paragraph 34
above).

36. Under cover of a letter dated 3 March 2015, Costa Rica communicated
to the Court a video which it wished to be included in the case file andf presented
at the hearings. By a letter dated 13 March 2015, Nicaragua stated that it had
no objection to Costa Rica’s request and presented certain comments on the
utility of the video ; it also announced that it would produce photographs in

response. By letters dated 23 March 2015, the Registrar informed the Parties
that the Court had decided to grant Costa Rica’s request.

37. By letters dated 16 March 2015, the Parties communicated the written
statements of the experts they intended to call at the hearings. Costa Rica also

asked the Court to extend to 20 March 2015 the time-limit within which the Par-
ties might transmit an agreement or their respective positions regardingf the allo-
cation of time for the cross -examination and re -examination of those experts,
which was granted by the Court. However, since the Parties were unable to
agree fully on this matter within the time -limit thus extended, the Registrar

informed them, by letters of 23 March 2015, of the Court’s decision in respect of
the maximum time that could be allocated for the examinations. In this connec -
tion, the Parties were invited to indicate the order in which they wished to pres -
ent their experts, and the precise amount of time they wished to reservef for the
cross-examination of each of the experts called by the other Party, which theyf

did by letters dated 30 March and 2 April 2015. By letters dated 10 April 2015,
the Registrar communicated to the Parties the detailed schedule for the exam -
ination of the experts, as adopted by the Court.
38. By letters of 23 March 2015, the Registrar informed the Parties that, in

relation to the Nicaragua v. Costa Rica case, the Court wished each of them to
produce, by 10 April 2015 at the latest, a map showing the San Juan River and
the road constructed by Costa Rica, and indicating the precise locations dis -
cussed in the key studies referred to in the written statements providedf to the
Court on 16 March 2015 (see paragraph 37 above). Under cover of letters dated
10 April 2015, Nicaragua and Costa Rica each provided the Court with printed

and electronic versions of the maps they had prepared.

39. By a letter dated 23 March 2015, Nicaragua, as announced (see para-
graph 36 above), communicated to the Court photographs that it wished to be
included in the case file. By a letter dated 31 March 2015, Costa Rica informed

the Court that it had no objection to Nicaragua’s request. By letters dated
8 April 2015, the Registrar informed the Parties that the Court had decided to
grant Nicaragua’s request.
40. By a letter dated 13 April 2015, Costa Rica requested that Nicaragua file
a copy of the report of Ramsar Advisory Mission No. 72 in relation to Nicara -

gua’s Refugio de Vida Silvestre Río San Juan (San Juan River Wildlife Refuge).
By a letter dated 16 April 2015, Nicaragua indicated that it was in possession
only of a draft report, in Spanish, which it enclosed with its letter. Sfubsequently,
under cover of a letter dated 24 April 2015, Nicaragua transmitted to the Court
the comments it had submitted on 30 November 2011 on the draft report of the

Ramsar Advisory Mission (original Spanish version and English translatifon of
certain extracts), as well as the reply from the Ramsar Secretariat datfed
19 December 2011 (original Spanish version only). The Parties later provided

17

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the Court with English translations of the documents submitted in Spanish by
Nicaragua.

41. By a letter dated 21 April 2015, the Registrar informed the Parties that

the Court had decided to request, under Article 62 of its Rules, that Nicaragua
produce the full text of two documents, excerpts of which were annexed tfo its
Counter-Memorial in the Costa Rica v. Nicaragua case. By a letter dated
24 April 2015, Nicaragua communicated to the Court the full text of the original
Spanish versions of the documents requested. Certified English translatifons were

transmitted by Nicaragua under cover of a letter dated 15 May 2015.

42. By letter of 28 April 2015, Costa Rica asked for photographs to be
included in the Nicaragua v. Costa Rica case file. In a letter dated 29 April 2015,
Nicaragua stated that it objected to this request, which it considered hfad been

made too late. By letters dated 29 April 2015, the Registrar informed the Parties
that the Court had decided not to grant Costa Rica’s request.

*

43. In accordance with Article 53, paragraph 2, of the Rules of Court, after
ascertaining the views of the Parties, the Court decided that copies of fthe plead-
ings and documents annexed would be made accessible to the public at the

opening of the oral proceedings.
44. Public hearings were held in the joined cases from 14ril 2015 to 1 May
2015. Between 14 and 17 April 2015 and 28 and 29 April 2015, the hearings
focused on the Costa Rica v. Nicaragua case, and between 20 and 24 April 2015
and 30 April and 1 May 2015 on the Nicaragua v. Costa Rica case. The Court

heard the oral arguments and replies of :
In the Costa Rica v. Nicaragua case,

For Costa Rica: H.E. Mr. Edgar Ugalde Alvarez,

H.E. Mr. Sergio Ugalde,
Mr. Arnoldo Brenes,
Mr. Samuel Wordsworth,
Mr. Marcelo Kohen,
Ms Kate Parlett,

Ms Katherine Del Mar.
For Nicaragua: H.E. Mr. Carlos José Argüello Gómez,
Mr. Alain Pellet,

Mr. Paul S. Reichler,
Mr. Andrew B. Loewenstein,
Mr. Stephen C. McCaffrey.

In the Nicaragua v. Costa Rica case,
For Nicaragua: H.E. Mr. Carlos José Argüello Gómez,

Mr. Paul S. Reichler,
Mr. Andrew B. Loewenstein,
Mr. Stephen C. McCaffrey,
Mr. Alain Pellet.

For Costa Rica: H.E. Mr. Edgar Ugalde Alvarez,
Mr. Arnoldo Brenes,

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5 Ord 1088.indb 33 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 680

Ms Katherine Del Mar,
Mr. Marcelo Kohen,
Mr. Samuel Wordsworth,
Ms Kate Parlett,

H.E. Mr. Sergio Ugalde.

45. In the Costa Rica v. Nicaragua case, Costa Rica called Mr. Thorne as an
expert during the public hearing of 14 April 2015 (afternoon). Later, during the
public hearing of 17 April 2015 (morning), Nicaragua called the following

experts : Mr. van Rhee and Mr. Kondolf. In the Nicaragua v. Costa Rica case,
Nicaragua called the following experts during the public hearings of
20 April 2015 (morning and afternoon): Mr. Weaver, Mr. Kondolf, Mr.Andrews
and Mr. Sheate. Costa Rica called Mr. Cowx and Mr. Thorne as experts during
the public hearing of 24 April 2015 (morning). A number of judges put ques -

tions to the experts, to which replies were given orally.
46. At the hearings, Members of the Court also put questions to the Parties,f
to which replies were given orally, in accordance with Article 61, paragraph 4,
of the Rules of Court.

* *

47. In its Application filed in the Costa Rica v. Nicaragua case, Costa Rica

made the following claims :
“For these reasons, and reserving the right to supplement, amplify orf

amend the present Application, Costa Rica requests the Court to adjudge
and declare that Nicaragua is in breach of its international obligations as
referred to in paragraph 1 of this Application as regards the incursion into
and occupation of Costa Rican territory, the serious damage inflicted to its
protected rainforests and wetlands, and the damage intended to the Colo -

rado River, wetlands and protected ecosystems, as well as the dredging afnd
canalization activities being carried out by Nicaragua on the San Juan
River.
In particular the Court is requested to adjudge and declare that, by its

conduct, Nicaragua has breached :
(a) the territory of the Republic of Costa Rica, as agreed and delimited by

the 1858Treaty of Limits, the Cleveland Award and the first and second
Alexander Awards;
(b) the fundamental principles of territorial integrity and the prohibition f
of use of force under the Charter of the United Nations and the

Charter of the Organization of American States ;
(c) the obligation imposed upon Nicaragua by Article IX of the 1858 Treaty
of Limits not to use the San Juan River to carry out hostile acts ;
(d) the obligation not to damage Costa Rican territory ;
(e) the obligation not to artificially channel the San Juan River away from f

its natural watercourse without the consent of Costa Rica ;
(f) the obligation not to prohibit the navigation on the San Juan River by
Costa Rican nationals;
(g) the obligation not to dredge the San Juan River if this causes damage
to Costa Rican territory (including the Colorado River), in accordance

with the 1888 Cleveland Award ;

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(h) the obligations under the Ramsar Convention on Wetlands ;

(i) the obligation not to aggravate and extend the dispute by adopting
measures against Costa Rica, including the expansion of the invaded

and occupied CostaRican territory or by adopting any further measure
or carrying out any further actions that would infringe Costa Rica’s
territorial integrity under international law.”

Costa Rica also requested the Court to “determine the reparation which must

be made by Nicaragua, in particular in relation to any measures of the kfind
referred to . . . above”.
48. In the course of the written proceedings in the Costa Rica v. Nicaragua
case, the following submissions were presented by the Parties :

On behalf of the Government of Costa Rica,

in the Memorial :

“For these reasons, and reserving the right to supplement, amplify orf
amend the present submissions :

1. Costa Rica requests the Court to adjudge and declare that, by its
conduct, Nicaragua has breached :

(a) the obligation to respect the sovereignty and territorial integrity of tfhe

Republic of Costa Rica, within the boundaries delimited by the
1858 Treaty of Limits and further defined by the Demarcation Com -
mission established by the Pacheco -Matus Convention, in particular by
the first and second Alexander Awards ;
(b) the prohibition of use of force under Article 2 (4) of the United Nations

Charter and Articles1, 19, 21 and 29 of the Charter of the Organization
of American States ;

(c) the obligation of Nicaragua under Article IX of the 1858 Treaty of
Limits not to use the San Juan to carry out hostile acts ;

(d) the rights of Costa Rican nationals to free navigation on the San Juan
in accordance with the 1858Treaty of Limits, the Cleveland Award and
the Court’s Judgment of 13 July 2009;
(e) the obligation not to dredge, divert or alter the course of the San Juanf,

or conduct any other works on the San Juan, if this causes damage to
Costa Rican territory (including the Colorado River), its environment,
or to Costa Rican rights in accordance with the Cleveland Award ;

(f) the obligation to consult with Costa Rica about implementing obliga-

tions arising from the Ramsar Convention, in particular the obligation
to co-ordinate future policies and regulations concerning the conserva-
tion of wetlands and their flora and fauna under Article 5 (1) of the
Ramsar Convention; and

(g) the Court’s Order for Provisional Measures of 8 March 2011;

20

5 Ord 1088.indb 37 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 682

and further to adjudge and declare that Nicaragua is :
(h) obliged to cease such breaches and to make reparation therefore.

2. The Court is requested to order, in consequence, that Nicaragua :

(a) withdraw any presence, including all troops and other personnel
(whether civilian, police or security, or volunteers) from that part off

Costa Rica known as Isla Portillos, on the right bank of the San Juan,
and prevent any return there of any such persons ;

(b) cease all dredging activities on the San Juan in the area between the
point of bifurcation of the Colorado River and the San Juan and the

outlet of the San Juan in the Caribbean Sea (‘the area’), pendinfg:
(i) an adequate environmental impact assessment ;

(ii) notification to CostaRica of further dredging plans for the area, not
less than three months prior to the implementation of such plans;
(iii) due consideration of any comments of Costa Rica made within one
month of notification ;

(c) not engage in any dredging operations or other works in the area if and f
to the extent that these may cause significant harm to Costa Rican
territory (including the Colorado River) or its environment, or to
impair Costa Rica’s rights under the Cleveland Award.

3. The Court is also requested to determine, in a separate phase, the

reparation and satisfaction to be made by Nicaragua.”
On behalf of the Government of Nicaragua,

in the Counter-Memorial :
“For the reasons given herein, the Republic of Nicaragua requests thef

Court to:
(1) dismiss and reject the requests and submissions of Costa Rica in her
pleadings;

(2) adjudge and declare that:
(i) Nicaragua enjoys full sovereignty over the caño joining Harbor

Head Lagoon with the San Juan River proper, the right bank of
which constitutes the land boundary as established by the
1858 Treaty as interpreted by the Cleveland and Alexander
Awards ;
(ii) Costa Rica is under an obligation to respect the sovereignty and

territorial integrity of Nicaragua, within the boundaries delimited
by the 1858 Treaty of Limits as interpreted by the Cleveland and
Alexander Awards;
(iii) Nicaragua is entitled, in accordance with the 1858 Treaty as inter -
preted by the subsequent arbitral awards, to execute works to

improve navigation on the San Juan River as it deems suitable,
and that these works include the dredging of the San Juan de Nic-
aragua River ; and,

21

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(iv) in so doing, Nicaragua is entitled as it deems suitable to -establish
the situation that existed at the time the 18Treaty was concluded;
(v) the only rights enjoyed by Costa Rica on the San Juan de Nicara-
gua River are those defined by said Treaty as interpreted by the

Cleveland and Alexander Awards.”
49. At the oral proceedings in the joined cases, the following submissions

were presented by the Parties in the Costa Rica v. Nicaragua case:
On behalf of the Government of Costa Rica,

at the hearing of 28 April 2015:

“For the reasons set out in the written and oral pleadings, the Repubflic
of Costa Rica requests the Court to :

(1) reject all Nicaraguan claims ;
(2) adjudge and declare that :

(a) sovereignty over the ‘disputed territory’, as defined by the Courtf in its
Orders of 8 March 2011 and 22 November 2013, belongs to the Repub -

lic of Costa Rica;
(b) by occupying and claiming Costa Rican territory, Nicaragua has
breached:

(i) theobligation to respect the sovereignty and territorial integrity of
the Republic of CostaRica, within the boundaries delimited by the
1858 Treaty of Limits and further defined by the Demarcation

Commission established by the Pacheco -Matus Convention, in
particular by the first and second Alexander Awards ;
(ii) theprohibition of the threat or use of force under Article 2 (4)of
the Charter of the United Nations and Article 22 of the Charter
of the Organization of American States ;

(iii) the prohibition to make the territory of other States the object,
even temporarily, of military occupation, contrary to Article 21 of
the Charter of the Organization of American States ; and
(iv) the obligation of Nicaragua under ArticleIX of the 1858 Treaty of

Limits not to use the San Juan River to carry out hostile acts ;
(c) by its further conduct, Nicaragua has breached :

(i) the obligation to respect Costa Rica’s territory and environment,
including its wetland of international importance under the

Ramsar Convention ‘Humedal Caribe Noreste’, on Costa Rican
territory;
(ii) Costa Rica’s perpetual rights of free navigation on the San Juan
in accordance with the 1858 Treaty of Limits, the 1888 Cleveland
Award and the Court’s Judgment of 13 July 2009 ;

(iii) the obligation to inform and consult with Costa Rica about
any dredging, diversion or alteration of the course of the San Juan
River, or any other works on the San Juan River that may
cause damage to Costa Rican territory (including the Colorado
River), its environment, or Costa Rican rights, in accordance

with the 1888 Cleveland Award and relevant treaty and customary
law;
(iv) the obligation to carry out an appropriate transboundary environ -

22

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mental impact assessment, which takes account of all potential
significant adverse impacts on Costa Rican territory;
(v) the obligation not to dredge, divert or alter the course of the San
Juan River, or conduct any other works on the San Juan River, if

this causes damage to Costa Rican territory (including the Colo -
rado River), its environment, or to Costa Rican rights under the
1888 Cleveland Award;
(vi) the obligations arising from the Orders of the Court indicat -
ing provisional measures of 8 March 2011 and 22 November

2013 ;
(vii) the obligation to consult with Costa Rica on the implementation
of obligations arising from the Ramsar Convention, in particular
the obligation to co -ordinate future policies and regulations con -
cerning the conservation of wetlands and their flora and fauna

under Article 5 (1) of the Ramsar Convention ; and
(viii) the agreement between the Parties, established in the exchange of
notes dated 19 and 22 September 2014, concerning navigation on
the San Juan River by Costa Rica to close the eastern caño con -
structed by Nicaragua in 2013 ;

(d) Nicaragua may not engage in any dredging operations or other works

if and to the extent that these may cause damage to Costa Rican terri -
tory (including the Colorado River) or its environment, or which
may impair Costa Rica’s rights under the 1888 Cleveland Award,
including its right not to have its territory occupied without its express
consent;

(3) to order, in consequence, that Nicaragua must :

(a) repeal, by means of its own choosing, those provisions of the Decree
No. 079-2009 and the Regulatory Norms annexed thereto of 1 October

2009 which are contrary to Costa Rica’s right of free navigation under
Article VI of the 1858Treaty of Limits, the 1888Cleveland Award, and
the Court’s Judgment of 13 July 2009 ;
(b) cease all dredging activities on the San Juan River in the vicinity of
Delta Costa Rica and in the lower San Juan River, pending :

(i) an appropriate transboundary environmental impact assessment,
which takes account of all potential significant adverse impacts on

Costa Rican territory, carried out by Nicaragua and provided to
Costa Rica;
(ii) formal written notification to Costa Rica of further dredging plans
in the vicinity of Delta Costa Rica and in the lower San Juan
River, not less than three months prior to the implementation of

any such plans ; and
(iii) due consideration of any comments made by Costa Rica upon
receipt of said notification ;

(c) make reparation in the form of compensation for the material damage
caused to Costa Rica, including but not limited to :

(i) damage arising from the construction of artificial caños and
destruction of trees and vegetation on the ‘disputed territory’ ;

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(ii) the cost of the remediation measures carried out by Costa Rica in
relation to those damages, including but not limited to those taken
to close the eastern caño constructed by Nicaragua in 2013, pur -
suant to paragraph 59 (2) (E) of the Court’s Order on provisional

measures of 22 November 2013;

the amount of such compensation to be determined in a separate
phase of these proceedings ;

(d) provide satisfaction so to achieve full reparation of the injuries causefd
to Costa Rica in a manner to be determined by the Court ;

(e) provide appropriate assurances and guarantees of non -repetition of
Nicaragua’s unlawful conduct, in such a form as the Court may order ;
and
(f) pay all of the costs and expenses incurred by Costa Rica in requesting
and obtaining the Order on provisional measures of 22November 2013,

including, but not limited to, the fees and expenses of Costa Rica’s
counsel and experts, with interest, on a full indemnity basis.”

On behalf of the Government of Nicaragua,

at the hearing of Wednesday 29 April 2015:
“In accordance with Article 60 of the Rules and the reasons given during the
written and oral phase of the pleadings the Republic of Nicaragua respecftfully

requests the Court to :
(a) dismiss and reject the requests and submissions of the Republic of

Costa Rica ;
(b) adjudge and declare that :

(i) Nicaragua enjoys full sovereignty over the caño joining Harbor
Head Lagoon with the San Juan River proper, the right bank of
which constitutes the land boundary as established by the
1858Treaty as interpreted by the Cleveland and Alexander Awards ;
(ii) Costa Rica is under an obligation to respect the sovereignty and

territorial integrity of Nicaragua, within the boundaries delimited
by the 1858 Treaty of Limits as interpreted by the Cleveland and
Alexander Awards;
(iii) Nicaragua is entitled, in accordance with the 1858 Treaty as inter -

preted by the subsequent arbitral awards, to execute works to
improve navigation on the San Juan River as it deems suitable,
and that these works include the dredging of the San Juan de Nic-
aragua River ;
(iv) the only rights enjoyed by Costa Rica on the San Juan de Nicara-

gua River are those defined by said Treaty as interpreted by the
Cleveland and Alexander Awards.”

*

50. In its Application filed in the Nicaragua v. Costa Rica case, Nicaragua
made the following claims :

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5 Ord 1088.indb 45 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 686

“On the basis of the foregoing statement of facts and law, Nicaragua,f
while reserving the right to supplement, amend or modify this Applicatiofn,
requests the Court to adjudge and declare that Costa Rica has breached :

(a) its obligation not to violate Nicaragua’s territorial integrity as deflim
ited by the 1858 Treaty of Limits, the Cleveland Award of 1888 and
the five Awards of the Umpire E. P. Alexander of 30 September 1897,

20 December 1897, 22 March 1898, 26 July 1899 and 10 March 1900;

(b) its obligation not to damage Nicaraguan territory ;

(c) its obligations under general international law and the relevant enviro-f

mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua
and Costa Rica (International System of Protected Areas for
Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and

Protection of the Main Wildlife Areas [Priority Wilderness Areas] in
Central America.

Furthermore, Nicaragua requests the Court to adjudge and declare that
Costa Rica must :

(a) restore the situation to the status quo ante ;
(b) pay for all damages caused including the costs added to the dredging
of the San Juan River ;
(c) not undertake any future development in the area without an appro -

priate transboundary environmental impact assessment and that this
assessment must be presented in a timely fashion to Nicaragua for its
analysis and reaction.

Finally, Nicaragua requests the Court to adjudge and declare that Costa f
Rica must:

(a) cease all the constructions underway that affect or may affect the rightfs
of Nicaragua;
(b) produce and present to Nicaragua an adequate environmental impact
assessment with all the details of the works.”

51. In the course of the written proceedings in the Nicaragua v. Costa Rica
case, the following submissions were presented by the Parties :

On behalf of the Government of Nicaragua,

in the Memorial :
“1. For the reasons given herein, the Republic of Nicaragua requests fthe

Court to adjudge and declare that, by its conduct, Costa Rica has breached:

(i) its obligation not to violate the integrity of Nicaragua’s territory fas
delimited by the 1858 Treaty of Limits, the Cleveland Award of 1888
and the five Awards of the Umpire E. P. Alexander of 30 Septem-
ber 1897, 20 December 1897, 22 March 1898, 26 July 1899 and

10 March 1900;
(ii) its obligation not to damage Nicaraguan territory ;

25

5 Ord 1088.indb 47 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 687

(iii) its obligations under general international law and the relevant environ-f
mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua
and Costa Rica (International System of Protected Areas for

Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and
Protection of the Main Wildlife Sites [Priority Wilderness Areas] in
Central America.

2. Furthermore, Nicaragua requests the Court to adjudge and declare
that Costa Rica must :

(i) cease all the constructions underway that affects or may affect the rights
of Nicaragua;

(ii) restore the situation to thestatus quo ante;
(iii) compensate for all damages caused including the costs added to the
dredging of the San Juan de Nicaragua River, with the amount of the
compensation to be determined in a subsequent phase of the case ;

(iv) not to continue or undertake any future development in the area with -
out an appropriate transboundary environmental impact assessment
and that this assessment must be presented in a timely fashion to Nica -
ragua for its analysis and reaction.

3. The Republic of Nicaragua further requests the Court to adjudge and
declare that:

(i) Nicaragua is entitled, in accordance with the 1858Treaty as interpreted
by the subsequent arbitral awards, to execute works to improve navi -
gation on the San Juan River as it deems suitable, and that these works f
include the dredging of the San Juan de Nicaragua River to remove
sedimentation and other barriers to navigation ; and,

(ii) in so doing, Nicaragua is entitled to re -establish the conditions of nav-
igation that existed at the time the 1858 Treaty was concluded ;
(iii) that the violations of the 1858Treaty and under many rules of interna-
tional law by Costa Rica, allow Nicaragua to take appropriate
countermeasures including the suspension of Costa Rica’s right of nav-

igation in the San Juan de Nicaragua River.

4. Finally, Nicaragua requests the Court to order Costa Rica to imme-
diately take the emergency measures recommended by its own experts and
further detailed in the Kondolf Report, in order to alleviate or mitigatfe the
continuing damage being caused to the San Juan de Nicaragua River and
the surrounding environment.

If Costa Rica does not of itself proceed to take these measures and the
Court considers it cannot order that it be done without the full procedufre
contemplated in Articles 73 et seq. of the Rules of Court, the Republic of
Nicaragua reserves its right to request provisional measures on the basifs of
Article 41 of the Statute and the pertinent procedures of Article 73 and ff.

of the Rules of Court and to amend and modify these submissions in the
light of the further pleadings in this case.”

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5 Ord 1088.indb 49 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 688

in the Reply :
“For the reasons given in its Memorial and in this Reply, the Republifc

of Nicaragua requests the Court to adjudge and declare that, by its condfuct,
the Republic of Costa Rica has breached :
(i) its obligation not to violate the integrity of Nicaragua’s territory fas

delimited by the 1858 Treaty of Limits as interpreted by the Cleveland
Award of 1888 and the five Awards of the Umpire E. P. Alexander of
30 September 1897, 20 December 1897, 22 March 1898, 26 July 1899,
and 10 March 1900 ;

(ii) its obligation not to damage Nicaraguan territory ;

(iii) its obligations under general international law and the relevant environ-f
mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua

and Costa Rica (International System of Protected Areas for
Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and
Protection of the Main Wildlife Sites [Priority Wilderness Areas] in
Central America.

2. Nicaragua also requests the Court to adjudge and declare that
Costa Rica must:

(i) cease all its continuing internationally wrongful acts that affect or arfe
likely to affect the rights of Nicaragua ;

(ii) inasmuch as possible, restore the situation to the status quo ante, in full
respect of Nicaragua’s sovereignty over the San Juan de Nicaragua
River, including by taking the emergency measures necessary to allevi -
ate or mitigate the continuing harm being caused to the river and the
surrounding environment;

(iii) compensate for all damages caused insofar as they are not made good
by restitution, including the costs added to the dredging of the San Juafn
de Nicaragua River, with the amount of the compensation to be deter -
mined in a subsequent phase of the case.

3. Furthermore, Nicaragua requests the Court to adjudge and declare
that Costa Rica must:

(i) not undertake any future development in the area without an appro -
priate transboundary environmental impact assessment and that this
assessment must be presented in a timely fashion to Nicaragua for its
analysis and reaction ;
(ii) refrain from using Route 1856 to transport hazardous material as long

as it has not given the guarantees that the road complies with the best f
construction practices and the highest regional and international stand -
ards of security for road traffic in similar situations.

4. The Republic of Nicaragua further requests the Court to adjudge and
declare that Nicaragua is entitled :

(i) in accordance with the 1858 Treaty as interpreted by the subsequent
arbitral awards, to execute works to improve navigation on the San

27

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Juan River and that these works include the dredging of the San Juan
de Nicaragua River to remove sedimentation and other barriers to nav-
igation ; and,
(ii) in so doing, to reestablish the conditions of navigation foreseen in the

1858 Treaty.
5. Finally, if the Court has not already appointed a neutral expert at the f

time when it adopts its Judgment, Nicaragua requests the Court to appoinft
such an expert who could advise the Parties in the implementation of thef
Judgment.”

On behalf of the Government of Costa Rica,
in the Counter -Memorial :

“For these reasons, and reserving the right to supplement, amplify orf
amend the present submissions, Costa Rica requests the Court to dismiss
all of Nicaragua’s claims in this proceeding.”

in the Rejoinder :

“For these reasons, and reserving the right to supplement, amplify orf
amend the present submissions, Costa Rica requests the Court to dismiss
all of Nicaragua’s claims in this proceeding.”

52. At the oral proceedings in the joined cases, the following submissions
were presented by the Parties in the Nicaragua v. Costa Rica case:

On behalf of the Government of Nicaragua,
at the hearing of 30 April 2015:

“1. In accordance with Article 60 of the Rules and the reasons given
during the written and oral phase of the pleadings the Republic of Nicarfa -

gua respectfully requests the Court to adjudge and declare that, by its fcon-
duct, the Republic of Costa Rica has breached :

(i) its obligation not to violate the integrity of Nicaragua’s territory fas
delimited by the 1858 Treaty of Limits as interpreted by the Cleveland
Award of 1888 and the five Awards of the Umpire E. P. Alexander of
30 September 1897, 20 December 1897, 22 March 1898, 26 July 1899,
and 10 March 1900 ;

(ii) its obligation not to damage Nicaraguan territory ;

(iii) its obligations under general international law and the relevant environ-f
mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua

and Costa Rica (International System of Protected Areas for
Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and
Protection of the Main Wildlife Sites in Central America.

2. Nicaragua also requests the Court to adjudge and declare that

Costa Rica must:

(i) cease all its continuing internationally wrongful acts that affect or arfe
likely to affect the rights of Nicaragua ;

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(ii) inasmuch as possible, restore the situation to the status quo ante, in full
respect of Nicaragua’s sovereignty over the San Juan de Nicaragua

River, including by taking the emergency measures necessary to allevi -
ate or mitigate the continuing harm being caused to the river and the
surrounding environment;
(iii) compensate for all damages caused insofar as they are not made good
by restitution, including the costs added to the dredging of the San Juafn
de Nicaragua River, with the amount of the compensation to be deter -

mined in a subsequent phase of the case.
3. Furthermore, Nicaragua requests the Court to adjudge and declare
that Costa Rica must :

(i) not undertake any future development in the area without an appro -
priate transboundary environmental impact assessment and that this
assessment must be presented in a timely fashion to Nicaragua for its

analysis and reaction ;
(ii) refrain from using Route 1856 to transport hazardous material as long
as it has not given the guarantees that the road complies with the best f
construction practices and the highest regional and international stand-
ards of security for road traffic in similar situations.

4. The Republic of Nicaragua further requests the Court to adjudge and
declare that Nicaragua is entitled :

(i) in accordance with the 1858Treaty as interpreted by the subsequent arbi-
tral awards, to execute works to improve navigation on the San Juan Rivefr
and that these works include the dredging of the San Juan de Nicaragua
River to remove sedimentation and other barriers to navigation.”

On behalf of the Government of Costa Rica,

at the hearing of 1 May 2015: “For the reasons set out in the written and oral
pleadings, Costa Rica requests the Court to dismiss all of Nicaragua’s claims in
this proceeding.”

*
* *

53. The Court will begin by dealing with the elements common to both
cases. It will thus address, in a first part, the question of its jurisdfiction,

before recalling, in a second part, the geographical and historical contfext
and the origin of the disputes.
The Court will then examine in turn, in two separate parts, the dis -

puted issues in the Costa Rica v. Nicaragua case and in the Nicaragua v.
Costa Rica case.

I. Jurisdiction of the Coufrt

54. With regard to the Costa Rica v. Nicaragua case, the Court recalls
that Costa Rica invokes, as bases of jurisdiction, Article XXXI of the

Pact of Bogotá and the declarations by which the Parties have recognifzed

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the compulsory jurisdiction of the Court under paragraphs 2 and 5 of
Article 36 of the Statute (see paragraph 2 above). It notes that Nicaragua

does not contest its jurisdiction to entertain Costaica’s claims.

The Court finds that it has jurisdiction over the dispute.
55. With regard to the Nicaragua v. Costa Rica case, the Court notes
that Nicaragua invokes, for its part, as bases of jurisdiction, ArticleXXXI

of the Pact of Bogotá and the above -mentioned declarations of accep -
tance (see paragraph 2 above). It further observes that Costa Rica does
not contest its jurisdiction to entertain Nicaragua’s claims.
The Court finds that it has jurisdiction over the dispute.

II. Geographical and Histforical Context
and Origin of the Disputfes

56. The San Juan River runs approximately 205 km from Lake Nica -
ragua to the Caribbean Sea. At a point known as “Delta Colorado” (for

“Delta Costa Rica”), the San Juan River divides into two branches : the
Lower San Juan is the northerly of these two branches and flows into tfhe
Caribbean Sea about 30 km downstream from the delta, near the town of
San Juan de Nicaragua, formerly known as San Juan del Norte or Grey -
town; the Colorado River is the southerly and larger of the two branches

and runs entirely within Costa Rica, reaching the Caribbean Sea at Barra
de Colorado, about 20 km south -east of the mouth of the Lower San
Juan. The Parties are in agreement that the Colorado River currently
receives approximately 90 per cent of the water of the San Juan River,
with the remaining 10 per cent flowing into the Lower San Juan.

57. The area situated between the Colorado River and the Lower San
Juan is broadly referred to as Isla Calero (approximately 150 sq km).
Within that area, there is a smaller region known to Costa Rica as Isla
Portillos and to Nicaragua as Harbor Head (approximately 17 sq km); it
is located north of the former Taura River. In the north of Isla Portillfos

is a lagoon, called Laguna Los Portillos by Costa Rica and Harbor Head
Lagoon by Nicaragua. This lagoon is at present separated from the
Caribbean Sea by a sandbar (see sketch -map No. 1 p. 692).

58. Isla Calero is part of the Humedal Caribe Noreste (Northeast Carib-

bean Wetland) which was designated by Costa Rica in 1996 as a wetland
of international importance under the Ramsar Convention. The area
immediately adjacent to it — including the San Juan River itself and a
strip of land 2 km in width abutting the river’s left (Nicaraguan) bank—
was designated by Nicaragua as a wetland of international importance
under the Ramsar Convention in 2001 and is known as the Refugio de

Vida Silvestre Río San Juan (San Juan River Wildlife Refuge).

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5 Ord 1088.indb 57 19/10/16 12:01 - 31 -

certain activities afnd construction of a rfoad (judgment) 692

W

83°30′

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84°45’W
UniversalTransverseMercatorprojection,zone11N

Lake gua
Nicara- Thissketchmaphasbeenpreparedforillustrativepurposesonly

11° 15’N 11° 0’N 10° 45’N 31

5 Ord 1088.indb 59 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 693

59. The present disputes between the Parties are set within a historical
context dating back to the 1850s. Following hostilities between the two f

States in 1857, the Governments of Costa Rica and Nicaragua signed on
15 April 1858 a Treaty of Limits, which was ratified by Costa Rica on
16 April 1858 and by Nicaragua on 26 April 1858 (hereinafter the
“1858 Treaty”). The 1858 Treaty fixed the course of the boundary between
Costa Rica and Nicaragua from the Pacific Ocean to the Caribbean Sea.

According to Article II of the Treaty (quoted in paragraph 71 below),
part of the boundary between the two States runs along the right
(Costa Rican) bank of the San Juan River from a point three English
miles below Castillo Viejo, a small town in Nicaragua, to “the end off
Punta de Castilla, at the mouth of the San Juan” on the Caribbean coast.
Article VI of the 1858 Treaty (quoted in paragraph 133 below) estab -

lished Nicaragua’s dominium and imperium over the waters of the river,
but at the same time affirmed Costa Rica’s right of free navigation on the
river for the purposes of commerce.
60. Following challenges by Nicaragua on various occasions to the
validity of the 1858 Treaty, Costa Rica and Nicaragua signed another

instrument on 24 December 1886, whereby the two States agreed to sub -
mit the question of the validity of the 1858 Treaty to the President of the
United States, Grover Cleveland, for arbitration. In addition, the Partifes
agreed that, if the 1858 Treaty were found to be valid, President Cleve-
land should also decide “upon all the other points of doubtful interpreta -

tion which either of the parties may find in the treaty”. On 22 June 1887,
Nicaragua communicated to Costa Rica 11 points of doubtful interpreta-
tion, which were subsequently submitted to President Cleveland for reso -
lution. The Cleveland Award of 1888 confirmed, in its paragraph 1, the
validity of the 1858 Treaty and found, in its paragraph 3 (1), that the
boundary line between the two States on the Atlantic side “begins at the

extremity of Punta de Castilla at the mouth of the San Juan de Nicaraguaf
River, as they both existed on the 15th day of April1858”. The Cleveland
Award also settled the other points of doubtful interpretation submittedf
by Nicaragua, such as the conditions under which Nicaragua may carry
out works of improvement on the San Juan River (para. 3 (6), quoted in

paragraph 116 below), the conditions under which Costa Rica may pre -
vent Nicaragua from diverting the waters of the San Juan (para. 3 (9),
quoted in paragraph 116 below), and the requirement that Nicaragua not
make any grants for the purpose of constructing a canal across its terrif -
tory without first asking for the opinion of Costa Rica (para. 3 (10)) or,

“where the construction of the canal will involve an injury to the natural
rights of Costa Rica”, obtaining its consent (para. 3 (11)).

61. Subsequent to the Cleveland Award, Costa Rica and Nicaragua

agreed in 1896, under the Pacheco -Matus Convention on border demar -
cation, to establish two national Demarcation Commissions, each com -

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5 Ord 1088.indb 61 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 694

posed of two members (Art. I). The Pacheco -Matus Convention further
provided that the Commissions would include an engineer, appointed by

the President of the United States of America, who “shall have broad f
powers to decide whatever kind of differences may arise in the course of
any operations and his ruling shall be final” (Art. II). United States Gen-
eral Edward Porter Alexander was so appointed. During the demarcation
process, which began in 1897 and was concluded in 1900, General Alex-

ander rendered five awards, the first three of which are of particular rfel -
evance to the Costa Rica v. Nicaragua case (see paragraphs 73-75 below).

62. Starting in the 1980s, some disagreements arose between Costa Rica
and Nicaragua concerning the precise scope of Costa Rica’s rights of

navigation under the 1858 Treaty. This dispute led Costa Rica to file an
Application with the Court instituting proceedings against Nicaragua on
29 September 2005. The Court rendered its Judgment on 13 July 2009,
which, inter alia, clarified Costa Rica’s navigational rights and the extent
of Nicaragua’s power to regulate navigation on the San Juan River (Dis ‑

pute regarding Navigational and Related Rights (Costa Rica v. Nicara‑
gua), Judgment, I.C.J. Reports 2009, p. 213).
63. On 18 October 2010, Nicaragua started dredging the San Juan
River in order to improve its navigability. It also carried out works inf the
northern part of Isla Portillos (see sketch -map No. 1 p .6 92). In this

regard, Costa Rica contends that Nicaragua artificially created a channel
(both Parties refer to such channels as “caños”) on Costa Rican territory,
in Isla Portillos between the San Juan River and Laguna Los Portillos/
Harbor Head Lagoon, whereas Nicaragua argues that it was only clear -
ing an existing caño on Nicaraguan territory. Nicaragua also sent some
military units and other personnel to that area. On 18 November 2010,

Costa Rica filed its Application instituting proceedings in the CostaRica v.
Nicaragua case (see paragraph 1 above). Costa Rica also submitted a
request for the indication of provisional measures under Article 41 of the
Statute (see paragraph 3 above).
64. In December 2010, Costa Rica started works for the construction of

Route 1856 Juan Rafael Mora Porras (hereinafter the “road”), which runfs
in Costa Rican territory along part of its border with Nicaragua. The
road has a planned length of 159.7 km, extending from Los Chiles in the
west to a point just beyond “Delta Colorado” in the east. For 108.f2 km,
it follows the course of the San Juan River (see sketch -map No. 2

p. 695). On 21 February 2011, Costa Rica adopted an Executive Decree
declaring a state of emergency in the border area, which Costa Rica
maintains exempted it from the obligation to conduct an environmental
impact assessment before constructing the road. On 22 December 2011,
Nicaragua filed its Application instituting proceedings in the Nicaragua v.
Costa Rica case (see paragraph 9 above), claiming in particular that the

construction of the road resulted in significant transboundary harm.

33

5 Ord 1088.indb 63 19/10/16 12:01 - 34 -
certain activities afnd construction of a rfoad (judgment) 695

W

83°30′

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11° 15’N 11° 0’N 10° 45’N
34

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III. Issues in theC osta RiCa v.N iCaRagua Case

A. Sovereignty over the Disputed Territory
and Alleged Breaches Thereof

65. Costa Rica submits that Nicaragua breached

“the obligation to respect the sovereignty and territorial integrity fof
the Republic of Costa Rica, within the boundaries delimited by the

1858 Treaty of Limits and further defined by the Demarcation Com -
mission established by the Pacheco -Matus Convention, in particular
by the first and second Alexander Awards” (final submissions,
para. 2 (b) (i)).

This claim is based on the premise that “[s]overeignty over the ‘dfisputed
territory’, as defined by the Court in its Orders of 8 March 2011 and
22 November 2013, belongs to the Republic of Costa Rica” (ibid.,

para. 2 (a)). In its final submissions Costa Rica requested the Court to
make a finding also on the issue of sovereignty over the disputed terri -
tory.
66. Costa Rica alleges that Nicaragua violated its territorial sover -

eignty in the area of Isla Portillos in particular by excavating in 2010f a
caño with the aim of connecting the San Juan River with the Harbor
Head Lagoon and laying claim to Costa Rican territory. According to
Costa Rica, this violation of sovereignty was exacerbated by Nicaragua’s
establishment of a military presence in the area and by its excavation ifn

2013 of two other caños located near the northern tip of Isla Portillos.

67. The Court notes that although the violations that allegedly took
place in 2013 occurred after the Application was made, they concern factfs

which are of the same nature as those covered in the Application and
which the Parties had the opportunity to discuss in their pleadings. Thefse
alleged violations may therefore be examined by the Court as part of thef
merits of the claim. They will later also be considered in relation to Nfica
ragua’s compliance with the Court’s Order on provisional measures fof

8 March 2011.
68. Nicaragua does not contest that it dredged the three caños, but
maintains that “Nicaragua enjoys full sovereignty over the caño joining
Harbor Head Lagoon with the San Juan River proper, the right bank of
which constitutes the land boundary as established by the 1858 Treaty as

interpreted by the Cleveland and Alexander Awards” (final submissionfs,
para. (b) (i)). Nicaragua further submits that “Costa Rica is under an
obligation to respect the sovereignty and territorial integrity of Nicarfa-
gua, within the boundaries delimited by the 1858 Treaty of Limits as

interpreted by the Cleveland and Alexander Awards” (ibid., para. (b) (ii)).
69. Since it is uncontested that Nicaragua conducted certain activities
in the disputed territory, it is necessary, in order to establish whethefr
there was a breach of Costa Rica’s territorial sovereignty, to determine

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which State has sovereignty over that territory. The “disputed territfory”
was defined by the Court in its Order of 8 March 2011 on provisional

measures as “the northern part of Isla Portillos, that is to say, thef area of
wetland of some 3 square kilometres between the right bank of the dis -
puted caño , the right bank of the San Juan River up to its mouth at the
Caribbean Sea and the Harbor Head Lagoon” (I.C.J. Reports 2011 (I),
p. 19, para. 55). The caño referred to is the one which was dredged by

Nicaragua in 2010. Nicaragua did not contest this definition of the “fdis -
puted territory”, while Costa Rica expressly endorsed it in its final sub -
missions (para. 2 (a)). The Court will maintain the definition of “disputed
territory” given in the 2011 Order. It recalls that its Order of 22 Novem-
ber 2013 indicating provisional measures specified that a Nicaraguan
military encampment “located on the beach and close to the line of veg -

etation” near one of the caños dredged in 2013 was “situated in the dis -
puted territory as defined by the Court in its Order of 8 March 2011”
(I.C.J. Reports 2013, p. 365, para. 46).

70. The above definition of the “disputed territory” does not specifi-

cally refer to the stretch of coast abutting the Caribbean Sea which liefs
between the Harbor Head Lagoon, which lagoon both Parties agree is
Nicaraguan, and the mouth of the San Juan River. In their oral argu -
ments the Parties expressed different views on this issue. However, theyf
did not address the question of the precise location of the mouth of thef

river nor did they provide detailed information concerning the coast. Nef-i
ther Party requested the Court to define the boundary more precisely witfh
regard to this coast. Accordingly, the Court will refrain from doing so.f
71. In their claims over the disputed territory both Parties rely on the
1858 Treaty, the Cleveland Award and the Alexander Awards. According
to Article II of the Treaty :

“The dividing line between the two Republics, starting from the
Northern Sea, shall begin at the end of Punta de Castilla, at the mouth

of the San Juan de Nicaragua River, and shall run along the right bank
of the said river up to a point three English miles distant from Castillfo
Viejo . . .” [In the Spanish original: “La línea divisoria de las dos Repú
blicas, partiendo del mar del Norte, comenzará en la extremidad de
Punta de Castilla, en la desembocadura del río de San Juan de Nicara ‑

gua, y continuará marcándose con la márgen derecha del expresado río,
hasta un punto distante del Castillo Viejo tres millas inglesas. . .”]

72. In 1888 President Cleveland found in his Award that :

“The boundary line between the Republics of Costa Rica and Nic-
aragua, on the Atlantic side, begins at the extremity of Punta de Cas-
tilla at the mouth of the San Juan de Nicaragua River, as they both
existed on the 15th day of April 1858. The ownership of any accretion
to said Punta de Castilla is to be governed by the laws applicable to

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that subject.” (United Nations, Reports of International Arbitral
Awards (RIAA), Vol. XXVIII, p. 209.)

73. When the Commissions on demarcation were established by the
Pacheco-Matus Convention, one member, to be designated by the Presi -

dent of the United States of America, was given the power to “resolve
any dispute between the Commissions of Costa Rica and Nicaragua aris-
ing from the operations” (see paragraph 61 above). According to this
Convention, the said person “shall have broad powers to decide whatevfer
kind of differences may arise in the course of any operations and his rufl -

ing shall be final” (Art. II, RIAA, Vol. XXVIII, p. 212). On this basis,
General Alexander, who had been duly designated to this position, ren -
dered five awards concerning the border. In his first Award he stated thfat
the boundary line :

“must follow the . . . branch . . . called the Lower San Juan, through
its harbor and into the sea.
The natural terminus of that line is the right -hand headland of the

harbor mouth.” (Ibid., p. 217.)
He observed that :

“throughout the treaty the river is treated and regarded as an outletf
of commerce. This implies that it is to be considered as in average
condition of water, in which condition alone it is navigable.” (Ibid.,

pp. 218-219.)
He then defined the initial part of the boundary starting from the Carib -
bean Sea in the following terms :

“The exact spot which was the extremity of the headland of Punta
de Castillo [on] April 15, 1858, has long been swept over by the Car -

ibbean Sea, and there is too little concurrence in the shore outline of f
the old maps to permit any certainty of statement of distance or exact
direction to it from the present headland. It was somewhere to the
north-eastward, and probably between 600 and 1,600 feet distant, but
it can not now be certainly located. Under these circumstances it best
fulfils the demands of the treaty and of President Cleveland’s award f

to adopt what is practically the headland of today, or the north-
western extremity of what seems to be the solid land, on the east side
of Harbor Head Lagoon.

I have accordingly made personal inspection of this ground, and

declare the initial line of the boundary to run as follows, to wit :
Its direction shall be due north-east and south-west, across the bank
of sand, from the Caribbean Sea into the waters of Harbor Head
Lagoon. It shall pass, at its nearest point, 300 feet on the north-west f

side from the small hut now standing in that vicinity. On reaching the
waters of Harbor Head Lagoon the boundary line shall turn to the

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left, or south-eastward, and shall follow the water’s edge around the

harbor until it reaches the river proper by the first channel met. Up
this channel, and up the river proper, the line shall continue to ascendf
as directed in the treaty.” (RIAA, Vol. XXVIII, p. 220.)

A sketch illustrating this initial part of the boundary in the geographifc
situation prevailing at the time was attached to this first Award ( ibid.,
p. 221). In that sketch, what the Arbitrator considered to be the “firsft

channel” was the branch of the Lower San Juan River which was then
flowing into the Harbor Head Lagoon (see sketch-map No. 3 below). The
same boundary line was sketched with greater precision in the proceed -
ings of the Commissions on demarcation.

74. The second Alexander Award envisaged the possibility that the
banks of the San Juan River would “not only gradually expand or con -
tract but that there [would] be wholesale changes in its channels”. Tfhe
Arbitrator observed that :

“Today’s boundary line must necessarily be affected in future by
all these gradual or sudden changes. But the impact in each case can

only be determined by the circumstances of the case itself, on a
case-by-case basis in accordance with such principles of international
law as may be applicable.
The proposed measurement and demarcation of the boundary line
will not have any effect on the application of those principles.” (RIAA,

Vol. XXVIII, p. 224.)

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5 Ord 1088.indb 73 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 700

75. In his third Award, General Alexander noted that “borders delim -
ited by waterways are likely to change when changes occur in the beds off

such waterways. In other words, it is the riverbed that affects changes fand
not the water within, over or below its banks.” ( RIAA, Vol. XXVIII,
p. 229.) He reached the following conclusion :

“Let me sum up briefly and provide a clearer understanding of the
entire question in accordance with the principles set out in my first
award, to wit, that in the practical interpretation of the 1858 Treaty,

the San Juan River must be considered a navigable river. I therefore
rule that the exact dividing line between the jurisdictions of the two
countries is the right bank of the river, with the water at ordinary
stage and navigable by ships and general -purpose boats. At that stage,
every portion of the waters of the river is under Nicaraguan jurisdic -
tion. Every portion of land on the right bank is under Costa Rican

jurisdiction.” (Ibid., p. 230.)

76. The Court considers that the 1858 Treaty and the awards by Presi-
dent Cleveland and General Alexander lead to the conclusion that Arti -
cle II of the 1858 Treaty, which places the boundary on the “right bank
of the . . . river”, must be interpreted in the context of Article VI (quoted
in full at paragraph 133 below), which provides that “the Republic of

Costa Rica shall . . . have a perpetual right of free navigation on the . . .
waters [of the river] between [its] mouth . . . and a point located three
English miles below Castillo Viejo”. As General Alexander observed inf
demarcating the boundary, the 1858 Treaty regards the river, “in average
condition of water”, as an “outlet of commerce” (see paragraphf 73
above). In the view of the Court, Articles II and VI, taken together, pro -

vide that the right bank of a channel of the river forms the boundary onf
the assumption that this channel is a navigable “outlet of commerce”f.
Thus, Costa Rica’s rights of navigation are linked with sovereignty over
the right bank, which has clearly been attributed to Costa Rica as far as
the mouth of the river.

77. Costa Rica contends that, while no channel of the San Juan River
now flows into the Harbor Head Lagoon, there has been no significant
shifting of the bed of the main channel of the Lower San Juan River since
the Alexander Awards. Costa Rica maintains that the territory on the

right bank of that channel as far as the river’s mouth in the Caribbefan
Sea should be regarded as under Costa Rican sovereignty. According to
Costa Rica, no importance should be given to what it considers to be an
artificial caño which was excavated by Nicaragua in 2010 in order to con -
nect the San Juan River with the Harbor Head Lagoon.
78. Nicaragua argues that, as a result of natural modifications in the

geographical configuration of the disputed territory, the “first chanfnel” to
which General Alexander referred in his first Award is now a channel

39

5 Ord 1088.indb 75 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 701

connecting the river, at a point south of the Harbor Head Lagoon, with
the southern tip of that lagoon. The channel in question, according to

Nicaragua, is the caño that it dredged in 2010 only to improve its naviga-
bility. Relying on the alleged existence of this caño over a number of years
and contending that it now marks the boundary, Nicaragua claims sover -
eignty over the whole of the disputed territory.
79. According to Nicaragua, the existence of the caño before 2010 is

confirmed by aerial and satellite imagery. In particular, Nicaragua allefges
that a satellite picture dating from 1961 shows that a caño existed where
Nicaragua was dredging in 2010.
80. Costa Rica points out that, especially by reason of the thick vege -
tation, aerial and satellite images of the disputed territory are not clfear,
including the satellite picture of 1961. Moreover, Costa Rica produces a

satellite image dating from August 2010, which would rule out the exis -
tence of a channel in the period between the clearing of vegetation in tfhe
location of the caño and the dredging of the caño. In the oral proceedings,
Nicaragua admitted that because of the tree canopy, only an inspection
on the ground could provide certainty regarding the caño.

81. In the opinion of the Court, an inspection would hardly be useful
for reconstructing the situation prevailing before 2010. The Court consifd -
ers that, given the general lack of clarity of satellite and aerial imagfes and
the fact that the channels that may be identified on such images do not f
correspond to the location of the caño dredged in 2010, this evidence is

insufficient to prove that a natural channel linked the San Juan River
with the Harbor Head Lagoon following the same course as the caño that
was dredged.
82. In order further to substantiate the view that the caño had existed
for some time before it was dredged, Nicaragua also supplies three affifda -
vits of Nicaraguan policemen or military agents who refer to a stream

linking the San Juan River with the lagoon and assert that it was navi -
gable for part of the year. Some affidavits of other agents mention strfeams
in the area of the lagoon and describe them as navigable by boats to a
certain extent, but do not specify their location.

83. The Court recalls that “[i]n determining the evidential weight of
any statement by an individual, the Court necessarily takes into account
its form and the circumstances in which it was made” (Application of the
Convention on the Prevention and Punishment of the Crime of Genocide
(Croatia v. Serbia), Judgment, I.C.J. Reports 2015 (I), p. 78, para. 196).

Affidavits will be treated “with caution”, in particular those mafde by
State officials for purposes of litigation (ibid., pp. 78, paras. 196-197,
referring to Territorial and Maritime Dispute between Nicaragua and Hon ‑
duras in the Caribbean Sea (Nicaragua v. Honduras), Judgment,
I.C.J. Reports 2007 (II), p. 731, para. 244). In the present case, the Court
finds that the affidavits of Nicaraguan State officials, which were prfepared

after the institution of proceedings by Costa Rica, provide little support
for Nicaragua’s contention.

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5 Ord 1088.indb 77 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 702

84. Nicaragua refers to a map produced in 1949 by the National Geo -
graphic Institute of Costa Rica which shows a caño in the location of the

one dredged in 2010. It acknowledges, however, that the map in question f
describes the entire disputed territory as being under Costa Rican sover-
eignty. Nicaragua further invokes a map published in 1971 by the same
Institute which shows a boundary close to the line claimed by Nicaragua.f
However, the Court notes that this evidence is contradicted by several

official maps of Nicaragua, in particular a map of 1967 of the Directorfate
of Cartography and a map, dating from 2003, published by the Nicara -
guan Institute of Territorial Studies (INETER, by its Spanish acronym)f,
which depict the disputed area as being under Costa Rica’s sovereignty.

85. As the Boundary Commission in the Eritrea/Ethiopia case stated,
in a passage that was quoted with approval by the Court in the case con -
cerning Sovereignty over Pedra Branca/Pulau Batu Puteh, Middle Rocks
and South Ledge (Malaysia/Singapore) , a map “stands as a statement of
geographical fact, especially when the State adversely affected has itself

produced and disseminated it, even against its own interest” (Judgment,
I.C.J. Reports 2008, p. 95, para. 271). In the present case, the evidence of
maps published by the Parties on the whole gives support to Costa Rica’s
position, but their significance is limited, given that they are all smafllle
maps which are not focused on the details of the disputed territory.

86. Both Parties invoke effectivités to corroborate their claims to ter -
ritorial sovereignty. Costa Rica argues that it had exercised sovereignty
over the disputed territory without being challenged by Nicaragua until f
2010. Costa Rica recalls that it adopted legislation applying specifically to

that area, that it issued permits or titles to use land in the same terrfitory,
and that Isla Portillos was included within the area it designated as a
wetland of international importance under the Ramsar Convention
(Humedal Caribe Noreste). Costa Rica notes that, when Nicaragua regis -
tered its own wetland of international importance concerning the area

(Refugio de Vida Silvestre Río San Juan), it only included the Harbor
Head Lagoon and did not encompass the disputed territory.

87. Nicaragua for its part contends that it acted as sovereign over the

disputed territory. Relying on affidavits by State officials and two pfolice
reports, it asserts that at least since the late 1970s the Nicaraguan arfmy,
navy and police have all patrolled the area in and around Harbor Head
Lagoon, including the caños connecting the lagoon with the San Juan
River.
88. Costa Rica questions the value of the evidence adduced by Nicara -

gua to substantiate its claim of having exercised sovereign powers in the
disputed territory.

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Nicaragua argues that Costa Rica’s claimed exercise of sovereignty was
merely a limited “paper presence” in the disputed territory not sufpported

by any actual conduct on the ground.
89. The effectivités invoked by the Parties, which the Court considers
are in any event of limited significance, cannot affect the title to sover -
eignty resulting from the 1858 Treaty and the Cleveland and Alexander
Awards.

90. The Court notes that the existence over a significant span of time
of a navigable caño in the location claimed by Nicaragua is put into ques-
tion by the fact that in the bed of the channel there were trees of consfide-
able size and age which had been cleared by Nicaragua in 2010. Moreover,f
as was noted by Costa Rica’s main expert, if the channel had been a dis -
tributary of the San Juan River, “sediment would have filled in, or aft a

minimum partially -filled, the southern part of the lagoon”. Furthermore,
the fact that, as the Parties’ experts agree, the caño dredged in 2010 no
longer connected the river with the lagoon by mid -summer 2011 casts
doubt on the existence over a number of years of a navigable channel folf -
lowing the same course before Nicaragua carried out its dredging activi -

ties. This caño could hardly have been the navigable outlet of commerce
referred to above (see paragraph 76).
91. If Nicaragua’s claim were accepted, Costa Rica would be prevented
from enjoying territorial sovereignty over the right bank of the San Juafn
River as far as its mouth, contrary to what is stated in the 1858 Treaty

and in the Cleveland Award. Moreover, according to Article VI of the
1858 Treaty (quoted below at paragraph 133), Costa Rica’s rights of nav -
igation are over the waters of the river, the right bank of which forms the
boundary between the two countries. As the Court noted (see para -
graph 76 above), these rights of navigation are linked with sovereignty
over the right bank.

92. The Court therefore concludes that the right bank of the caño
which Nicaragua dredged in 2010 is not part of the boundary between
Costa Rica and Nicaragua, and that the territory under Costa Rica’s sov-
ereignty extends to the right bank of the Lower San Juan River as far asf
its mouth in the Caribbean Sea. Sovereignty over the disputed territory f

thus belongs to Costa Rica.
93. It is not contested that Nicaragua carried out various activities in
the disputed territory since 2010, including excavating three caños and
establishing a military presence in parts of that territory. These activfities
were in breach of Costa Rica’s territorial sovereignty. Nicaragua is

responsible for these breaches and consequently incurs the obligation tof
make reparation for the damage caused by its unlawful activities (see Sec -
tion E).
94. Costa Rica submits that “by occupying and claiming Costa Rican
territory” Nicaragua also committed other breaches of its obligationsf.

95. Costa Rica’s final submission 2 (b) (iv) asks the Court to adjudge
and declare that Nicaragua breached its obligation “not to use the Safn

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5 Ord 1088.indb 81 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 704

Juan River to carry out hostile acts” under Article IX of the 1858 Treaty.
This provision reads as follows :

“Under no circumstances, and even in [the] case that the Republics
of Costa Rica and Nicaragua should unhappily find themselves in a

state of war, neither of them shall be allowed to commit any act of
hostility against the other, whether in the port of San Juan del Norte,
or in the San Juan River, or the Lake of Nicaragua.” [In the Spanish f
original: “Por ningún motivo, ni en caso y estado de guerra, en que por
desgracia llegasen á encontrarse las Repúblicas de Nicaragua y

Costa Rica, les será permitido ejercer ningún acto de hostilidad entre
ellas en el puerto de San Juan del Norte, ni en el río de este nombre▯ y
Lago de Nicaragua.”]

No evidence of hostilities in the San Juan River has been provided. Therfe -
fore the submission concerning the breach of Nicaragua’s obligations f
under Article IX of the Treaty must be rejected.

96. In its final submission 2 (b) (ii), Costa Rica asks the Court to find

a breach by Nicaragua of “the prohibition of the threat or use of forfce
under Article 2 (4) of the Charter of the United Nations and Article 22 of
the Charter of the Organization of American States”.

97. The relevant conduct of Nicaragua has already been addressed in

the context of the Court’s examination of the violation of Costa Rica’s
territorial sovereignty. The fact that Nicaragua considered that its actfivi-
ties were taking place on its own territory does not exclude the possibiflity
of characterizing them as an unlawful use of force. This raises the issufe of
their compatibility with both the United Nations Charter and the Charterf
of the Organization of American States. However, in the circumstances,

given that the unlawful character of these activities has already been
established, the Court need not dwell any further on this submission. Asf
in the case concerning Land and Maritime Boundary between Cameroon
and Nigeria (Cameroon v. Nigeria : Equatorial Guinea intervening) , the
Court finds that, “by the very fact of the present Judgment and of thfe

evacuation” of the disputed territory, the injury suffered by Costa Rica
“will in all events have been sufficiently addressed” (Judgment,
I.C.J. Reports 2002, p. 452, para. 319).
98. In its final submission 2 (b) (iii), Costa Rica requests the Court to
find that Nicaragua made the territory of Costa Rica “the object, even

temporarily, of military occupation, contrary to Article 21 of the Charter
of the Organization of American States”. The first sentence of this pfrovi -
sion stipulates: “The territory of a State is inviolable ; it may not be the
object, even temporarily, of military occupation or of other measures off
force taken by another State, directly or indirectly, on any grounds whaft-
ever.”

In order to substantiate this claim, Costa Rica refers to the presence of
military personnel of Nicaragua in the disputed territory.

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5 Ord 1088.indb 83 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 705

99. The Court has already established that the presence of military per-
sonnel of Nicaragua in the disputed territory was unlawful because it vifo-

lated Costa Rica’s territorial sovereignty. The Court does not need to
ascertain whether this conduct of Nicaragua constitutes a military occu -
pation in breach of Article 21 of the Charter of the Organization of
American States.

B. Alleged Violations of International Environmental Law

100. The Court will now turn to Costa Rica’s allegations concerning
violations by Nicaragua of its obligations under international environ -
mental law in connection with its dredging activities to improve the navfi-
gability of the Lower San Juan River. Costa Rica’s environmental claims

can be grouped into two broad categories. First, according to Costa Rica,
Nicaragua breached the procedural obligations to carry out an appropri -
ate transboundary environmental impact assessment of its dredging
works, and to notify, and consult with, Costa Rica regarding those works.
Secondly, Costa Rica alleges that Nicaragua breached the substantive

environmental obligation not to cause harm to Costa Rica’s territory.
The Court will consider Costa Rica’s allegations in turn.

1. Procedural obligations

(a) The alleged breach of the obligation to carry out an environmental
impact assessment

101. The Parties broadly agree on the existence in general international

law of an obligation to conduct an environmental impact assessment con-
cerning activities carried out within a State’s jurisdiction that risfk causing
significant harm to other States, particularly in areas or regions of shfared
environmental conditions.

102. Costa Rica claims that Nicaragua has not complied with that
obligation, and must do so in advance of any further dredging. It submitfs
in particular that the analysis carried out in the Environmental Impact f
Study undertaken by Nicaragua in 2006 does not support the conclusion
that the dredging project would cause no harm to the flow of the Colo -

rado River. Moreover, according to Costa Rica, the Environmental
Impact Study did not assess the impact of the dredging programme on
the wetlands. Costa Rica maintains that the artificial changes to the mor -
phology of the river resulting from Nicaragua’s dredging activities rfisked
causing an adverse impact on those wetlands. Costa Rica also argues that

a document entitled “Report : Ramsar Advisory Mission No. 72”, pre-
pared in April 2011, confirms the existence of a risk of transboundary

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5 Ord 1088.indb 85 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 706

harm, shows that Nicaragua’s study did not contain an assessment of that
risk, and concludes that such an assessment should have been undertaken f

prior to the implementation of the dredging programme.
103. Nicaragua contends for its part that its 2006 Environmental
Impact Study and the related documentation fully addressed the potentialf
transboundary impact of its dredging programme, including its effects onf
the environment of Costa Rica and the possible reduction in flow of the

Colorado River. It points out that this study concluded that the pro -
gramme posed no risk of significant transboundary harm and would actu-
ally have beneficial effects for the San Juan River and the surrounding
area. As to the document entitled “Report : Ramsar Advisory Mission
No. 72”, Nicaragua argues that it was only a draft report, on which Nica-
ragua commented in a timely manner, but which the Ramsar Secretariat

never finalized ; accordingly, it should be given no weight. Furthermore,
Nicaragua explains that the report’s conclusion that there had been nfo
analysis of the impact of the dredging programme on the hydrology of
the area was incorrect, as Nicaragua pointed out in the comments it sub -
mitted to the Ramsar Secretariat.

*

104. As the Court has had occasion to emphasize in its Judgment in

the case concerning Pulp Mills on the River Uruguay (Argentina v. Uru‑
guay) :
“the principle of prevention, as a customary rule, has its origins inf the

due diligence that is required of a State in its territory. It is ‘every
State’s obligation not to allow knowingly its territory to be used fofr
acts contrary to the rights of other States’ (Corfu Channel (United
Kingdom v. Albania), Merits, Judgment, I.C.J. Reports 1949, p. 22).
A State is thus obliged to use all the means at its disposal in order tof

avoid activities which take place in its territory, or in any area underf
its jurisdiction, causing significant damage to the environment of
another State.” (Judgment, I.C.J. Reports 2010 (I), pp. 55-56,
para. 101.)

Furthermore, the Court concluded in that case that“it may now be consid -
ered a requirement under general international law to undertake an envir -
onmental impact assessment where there is a risk that the proposed

industrial activity may have a significant adverse impact in a transbound-
ary context, in particular, on a shared resource” (ibid., p. 83, para. 204).
Although the Court’s statement in the Pulp Mills case refers to industrial
activities, the underlying principle applies generally to proposed activfities
which may have a significant adverse impact in a transboundary context. f
Thus, to fulfil its obligation to exercise due diligence in preventing signifi-

cant transboundary environmental harm, a State must, before embarking
on an activity having the potential adversely to affect the environment of

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5 Ord 1088.indb 87 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 707

another State, ascertain if there is a risk of significant transboundaryf

harm, which would trigger the requirement to carry out an environmental f
impact assessment.

Determination of the content of the environmental impact assessment

should be made in light of the specific circumstances of each case. As tfhe
Court held in the Pulp Mills case :

“it is for each State to determine in its domestic legislation or in fthe
authorization process for the project, the specific content of the envir-f
onmental impact assessment required in each case, having regard to
the nature and magnitude of the proposed development and its likely
adverse impact on the environment as well as to the need to exercise

due diligence in conducting such an assessment” ( I.C.J. Reports
2010 (I), p. 83, para. 205).

If the environmental impact assessment confirms that there is a risk of fsig -
nificant transboundary harm, the State planning to undertake the activitfy
is required, in conformity with its due diligence obligation, to notify fand
consult in good faith with the potentially affected State, where that isf nece-
sary to determine the appropriate measures to prevent or mitigate that rfisk.
105. The Court notes that the risk to the wetlands alleged by CostaRica

refers to Nicaragua’s dredging activities as a whole, including the dfredg -
ing of the 2010 caño. The Court recalls that the dredging activities carried
out in breach of Costa Rica’s territorial sovereignty have been considered
previously. Accordingly, the Court will confine its analysis to ascertaining
whether Nicaragua’s dredging activities in the Lower San Juan carriedf a

risk of significant transboundary harm. The principal risk cited by
Costa Rica was the potential adverse impact of those dredging activities
on the flow of the Colorado River, which could also adversely affect
Costa Rica’s wetland. In 2006, Nicaragua conducted a study of the impact
that the dredging programme would have on its own environment, which
also stated that the programme would not have a significant impact on

the flow of the Colorado River. This conclusion was later confirmed byf
both Parties’ experts. Having examined the evidence in the case file,f
including the reports submitted and testimony given by experts called byf
both Parties, the Court finds that the dredging programme planned in
2006 was not such as to give rise to a risk of significant transboundaryf
harm, either with respect to the flow of the Colorado River or to

Costa Rica’s wetland. In light of the absence of risk of significant trans -
boundary harm, Nicaragua was not required to carry out an environmen-
tal impact assessment.

(b) The alleged breach of an obligation to notify and consult

106. The Parties concur on the existence in general international law of

an obligation to notify, and consult with, the potentially affected Statfe in

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5 Ord 1088.indb 89 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 708

respect of activities which carry a risk of significant transboundary hafrm.
Costa Rica contends that, in addition to its obligations under general

international law, Nicaragua was under a duty to notify and consult with
it as a result of treaty obligations binding on the Parties. First, it afsserts
that Article 3, paragraph 2, and Article 5 of the Ramsar Convention pro-
vide for a duty to notify and consult. Secondly, it submits that Arti -
cles 13 (g) and 33 of the Convention for the Conservation of the

Biodiversity and Protection of Priority Wilderness Areas in Central
America establish an obligation to share information related to activitifes
which may be particularly damaging to biological resources.

107. While not contesting the existence of an obligation to notify and

consult under general international law, Nicaragua asserts that in the
present case such obligation is limited by the 1858 Treaty, as interpreted
by the Cleveland Award, which constitutes the lex specialis with respect
to procedural obligations. For Nicaragua, since the 1858 Treaty contains
no duty to notify or consult with respect to dredging or any other “wforks

of improvement”, any such duty in customary or treaty law does not
apply to the facts of the case. In any event, Nicaragua asserts that a dfuty
to notify and consult would not be triggered because both countries’ f
studies have shown that Nicaragua’s dredging programme posed no like -
lihood of significant transboundary harm. Nicaragua further argues that f

neither Article 3, paragraph 2, nor Article 5 of the Ramsar Convention is
applicable to the facts of the case. With respect to the Convention for fthe
Conservation of the Biodiversity and Protection of Priority Wilderness
Areas in Central America, Nicaragua asserts that it does not set out an f
obligation to share information relating to activities which may be par -
ticularly damaging to biological resources; at most it encourages States to

do so.

*

108. The Court observes that the fact that the 1858 Treaty may con -
tain limited obligations concerning notification or consultation in specfific
situations does not exclude any other procedural obligations with regardf
to transboundary harm which may exist in treaty or customary interna -

tional law. In any event, the Court finds that, since Nicaragua was not f
under an international obligation to carry out an environmental impact
assessment in light of the absence of risk of significant transboundary
harm (see paragraph 105 above), it was not required to notify, or consult
with, Costa Rica.

109. As to the alleged existence of an obligation to notify and consult
in treaties binding on the Parties, the Court observes that both CostaRica

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5 Ord 1088.indb 91 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 709

and Nicaragua are parties to the Ramsar Convention and the Convention

for the Conservation of the Biodiversity and Protection of Priority
Wilderness Areas in Central America. The Court recalls that Article 3,
paragraph 2, of the Ramsar Convention provides that :

“Each Contracting Party shall arrange to be informed at the earli -
est possible time if the ecological character of any wetland in its ter -
ritory and included in the List [of wetlands of international importancef]

has changed, is changing or is likely to change as the result of tech -
nological developments, pollution or other human interference. Infor-
mation on such changes shall be passed without delay to the [Ramsar
Secretariat].”

While this provision contains an obligation to notify, that obligation ifs

limited to notifying the Ramsar Secretariat of changes or likely changesf
in the “ecological character of any wetland” in the territory of tfhe notify-
ing State. In the present case, the evidence before the Court does not
indicate that Nicaragua’s dredging programme has brought about any
changes in the ecological character of the wetland, or that it was likely to

do so unless it were to be expanded. Thus the Court finds that no obligaf -
tion to inform the Ramsar Secretariat arose for Nicaragua.

110. The Court further recalls that Article 5 of the Ramsar Convention
provides that:

“The Contracting Parties shall consult with each other about imple -
menting obligations arising from the Convention especially in the case
of a wetland extending over the territories of more than one Contract -
ing Party or where a water system is shared by Contracting Parties.
They shall at the same time endeavour to co -ordinate and support

present and future policies and regulations concerning the conserva -
tion of wetlands and their flora and fauna.”

While this provision contains a general obligation to consult “about f
implementing obligations arising from the Convention”, it does not crfe -
ate an obligation on Nicaragua to consult with Costa Rica concerning a
particular project that it is undertaking, in this case the dredging of fthe

Lower San Juan River. In light of the above, Nicaragua was not required f
under the Ramsar Convention to notify, or consult with, Costa Rica
prior to commencing its dredging project.
111. As to the Convention for the Conservation of the Biodiversity
and Protection of Priority Wilderness Areas in Central America, the

Court sees no need to take its enquiry further, as neither of the two prfov-i

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5 Ord 1088.indb 93 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 710

sions invoked by Costa Rica contains a binding obligation to notify or
consult.

(c) Conclusion

112. In light of the above, the Court concludes that it has not been
established that Nicaragua breached any procedural obligations owed to
Costa Rica under treaties or the customary international law of the envir-

onment. The Court takes note of Nicaragua’s commitment, made in the
course of the oral proceedings, to carry out a new Environmental Impact f
Study before any substantial expansion of its current dredging pro -
gramme. The Court further notes that Nicaragua stated that such a study f
would include an assessment of the risk of transboundary harm, and that f

it would notify, and consult with, Costa Rica as part of that process.

2. Substantive obligations concerning transboundary harm

113. The Court has already found that Nicaragua is responsible for the
harm caused by its activities in breach of Costa Rica’s territorial sover -
eignty. What remains to be examined is whether Nicaragua is responsible
for any transboundary harm allegedly caused by its dredging activities
which have taken place in areas under Nicaragua’s territorial sovereifgnty,

in the Lower San Juan River and on its left bank.

114. Costa Rica submits that Nicaragua has breached “the obligation
not to dredge, divert or alter the course of the San Juan River, or condfuct
any other works on the San Juan River, if this causes damage to

Costa Rican territory (including the Colorado River), its environment, or
to Costa Rican rights under the 1888 Cleveland Award” (final submis -
sions, para. 2 (c) (v)). According to Costa Rica, the dredging programme
executed by Nicaragua in the Lower San Juan River was in breach of
Nicaragua’s obligations under customary international law and caused

harm to Costa Rican lands on the right bank of the river and to the
Colorado River.

115. Nicaragua contends that the dredging programme has not caused
any harm to Costa Rican territory including the Colorado River. It

argues that the execution of the dredging programme has been beneficial f
to the dredged section of the Lower San Juan River and to the wetlands
of international importance lying downstream. Moreover, Nicaragua
maintains that, under a special rule stated in the Cleveland Award and
applying to the San Juan River, even if damage to Costa Rica’s territory

resulted from the works to maintain and improve the river, the dredging f
activities would not be unlawful.

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116. Both Parties referred to the passage in the Cleveland Award which
reads as follows :

“The Republic of Costa Rica cannot prevent the Republic of Nic -
aragua from executing at her own expense and within her own terri -

tory such works of improvement, provided such works of improvement
do not result in the occupation or flooding or damage of Costa Rica
territory, or in the destruction or serious impairment of the navigationf
of the said river or any of its branches at any point where Costa Rica
is entitled to navigate the same. The Republic of Costa Rica has the

right to demand indemnification for any places belonging to her on
the right bank of the River San Juan which may be occupied without
her consent, and for any lands on the same bank which may be
flooded or damaged in any other way in consequence of works of
improvement.” (RIAA, Vol. XXVIII, p. 210, para. 3 (6); emphasis in
the original.)

Both Parties also referred to the following passage in the same Award :

“The Republic of Costa Rica can deny to the Republic of Nicara -

gua the right of deviating the waters of the River San Juan in case
such deviation will result in the destruction or serious impairment of
the navigation of the said river or any of its branches at any point
where Costa Rica is entitled to navigate the same.” (Ibid., para.3 (9).)

117. According to Nicaragua, the statements in the Cleveland Award
quoted above should be understood as implying that Nicaragua is free to f
undertake any dredging activity, possibly even if it is harmful to

Costa Rica. On the other hand, according to Costa Rica, Nicaragua
would be under an obligation to pay compensation for any harm caused
to Costa Rica, whether the harm was significant or not and whether Nica -
ragua was or was not diligent in ensuring that the environment of
Costa Rica would not be affected ;damage caused by “unforeseeable or

uncontrollable events” related to dredging activities would also havef to
be compensated by Nicaragua. Costa Rica also argued that “all of Nica -
ragua’s rights and obligations under the 1858 Treaty and the 1888 Award
must be interpreted in the light of principles for the protection of thef
environment in force today” and that the Treaty and the Award do not f

“override the application of environmental obligations under general f
principles of law and under international treaties” requiring States fnot to
cause significant transboundary harm.
118. As the Court restated in the Pulp Mills case, under customary
international law, “[a] State is . . obliged to use all the means at its dis -
posal in order to avoid activities which take place in its territory, orf in

any area under its jurisdiction, causing significant damage to the envirfon-
ment of another State” (I.C.J. Reports 2010 (I), p. 56, para. 101; see also

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Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion,
I.C.J. Reports 1996 (I), pp. 241-242, para. 29).

In any event, it would be necessary for the Court to address the ques -
tion of the relationship between the 1858 Treaty as interpreted by the
Cleveland Award and the current rule of customary international law
with regard to transboundary harm only if Costa Rica were to prove that

the dredging programme in the Lower San Juan River produced harm to
Costa Rica’s territory.
119. Costa Rica has not provided any convincing evidence that sedi -
ments dredged from the river were deposited on its right bank. Costa Rica
has also not proved that the dredging programme caused harm to its wet -
land (see paragraph 109 above). With regard to Costa Rica’s contention

that “the dredging programme has had a significant effect upon the Coflo-
rado River”, it has already been noted that the Parties agree that atf the
so-called “Delta Colorado” the Colorado River receives about 90 per cent
of the waters flowing through the San Juan River (see paragraph 56
above). Nicaragua estimates that the diversion of water from the Colo -

rado River due to the dredging of the Lower San Juan River affected lessf
than 2 per cent of the waters flowing into the Colorado River. No higher
figure has been suggested by Costa Rica. Its main expert observed that
“there is no evidence that the dredging programme has significantly
affected flows in the Río Colorado”. Costa Rica did adduce evidence indi -

cating a significant reduction in flow of the Colorado River between Jan -
uary 2011 and October 2014. However, the Court considers that a causal
link between this reduction and Nicaragua’s dredging programme has noft
been established. As Costa Rica admits, other factors may be relevant to
the decrease in flow, most notably the relatively small amount of rainffall
in the relevant period. In any event, the diversion of water due to the f

dredging of the Lower San Juan River is far from seriously impairing
navigation on the Colorado River, as envisaged in paragraph 3 (9) of the
Cleveland Award, or otherwise causing harm to Costa Rica.

120. The Court therefore concludes that the available evidence does

not show that Nicaragua breached its obligations by engaging in dredgingf
activities in the Lower San Juan River.

C. Compliance with Provisional Measures

121. In its final submissions Costa Rica contends that Nicaragua has
also breached its “obligations arising from the Orders of the Court ifndi-
cating provisional measures of 8 March 2011 and 22 November 2013”
(para. 2 (c) (vi)).
122. Nicaragua, for its part, raised certain issues about Costa Rica’s

compliance with some of the provisional measures adopted by the Court,
but did not request the Court to make a finding on this matter.

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123. In its Order on provisional measures of 8 March 2011 the Court
indicated that “[e]ach Party shall refrain from sending to, or maintafining in

the disputed territory, including the caño, any personnel, whether civilian,
police or security”; the Court also required each Party to “refrain from any
action which might aggravate or extend the dispute before the Court or
make it more difficult to resolve” (I.C.J.Reports 2011 (I), p. 27, para. 86).
124. Costa Rica argued that the presence in the disputed territory of

large groups of Nicaraguan civilians who were members of an environ -
mental movement constituted a breach of the 2011 Order. Nicaragua
denied this. In its Order of 16 July 2013, the Court specified that “the
presence of organized groups of Nicaraguan nationals in the disputed
area carrie[d] the risk of incidents which might aggravate the . . . dispute”
(I.C.J. Reports 2013, p. 240, para. 37).

125. Costa Rica maintained and Nicaragua later acknowledged that
the excavation of the second and third caños took place after the 2011
Order had been adopted, that this activity was attributable to Nicaraguaf
and that moreover a military encampment had been installed on the dis -

puted territory as defined by the Court. In the oral hearings Nicaragua f
also acknowledged that the excavation of the second and third caños rep-
resented an infringement of its obligations under the 2011 Order.

126. The Court already ascertained these facts in its Order of

22 November 2013 (ibid., pp. 364-365, paras. 45-46). However, that state-
ment was only instrumental in ensuring the protection of the rights of tfhe
Parties during the judicial proceedings. The judgment on the merits is tfhe
appropriate place for the Court to assess compliance with the provisionafl
measures. Thus, contrary to what was argued by Nicaragua, a statement
of the existence of a breach to be included in the present Judgment cannfot

be viewed as “redundant”. Nor can it be said that any responsibilifty for
the breach has ceased : what may have ceased is the breach, not the
responsibility arising from the breach.
127. On the basis of the facts that have become uncontested, the Court
accordingly finds that Nicaragua breached its obligations under the Ordefr

of 8 March 2011 by excavating two caños and establishing a military pres -
ence in the disputed territory.
128. The Court’s Order of 22 November 2013 required the following
measures from Nicaragua: to “refrain from any dredging and other activ-
ities in the disputed territory” ; to “fill the trench on the beach north of

the eastern caño” ; to “cause the removal from the disputed territory of
any personnel, whether civilian, police or security” ; to “prevent any such
personnel from entering the disputed territory” ; and to “cause the
removal from and prevent the entrance into the disputed territory of anyf
private persons under its jurisdiction or control” ( ibid., p. 369, para. 59).
No allegations of subsequent breaches of any of these obligations were

made by Costa Rica, which only maintained that some of Nicaragua’s
activities after this Order were in breach of its obligation not to aggrfavate

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the dispute, which had been stated in the 2011 Order. The Court does notf
find that a breach of this obligation has been demonstrated on the basisf

of the available evidence.
129. The Court thus concludes that Nicaragua acted in breach of its
obligations under the 2011 Order by excavating the second and third
caños and by establishing a military presence in the disputed territory.
The Court observes that this finding is independent of the conclusion seft

out above (see Section A) that the same conduct also constitutes a viola -
tion of the territorial sovereignty of Costa Rica.

D. Rights of Navigation

130. In its final submissions Costa Rica also claims that Nicaragua has
breached “Costa Rica’s perpetual rights of free navigation on the San
Juan in accordance with the 1858 Treaty of Limits, the 1888 Cleveland
Award and the Court’s Judgment of 13 July 2009” (final submissions,

para. 2 (c) (ii)).
131. Nicaragua contests the admissibility of this submission, which it
considers not covered by the Application and as having an object uncon -
nected with that of the “main dispute”. Costa Rica points out that it had
already requested in its Application (para. 41 (f)) that the Court adjudge

and declare that, “by its conduct, Nicaragua has breached . . . the obliga-
tion not to prohibit the navigation on the San Juan River by Costa Rican
nationals”.
132. The Court observes that, although Costa Rica’s submission could
have been understood as related to the “dredging and canalization activi -

ties being carried out by Nicaragua on the San Juan River”, to which fthe
same paragraph of the Application also referred, the wording of the sub -
mission quoted above did not contain any restriction to that effect. Thef
Court considers that Costa Rica’s final submission concerning rights of
navigation is admissible.

133. Article VI of the 1858 Treaty provides that :
“The Republic of Nicaragua shall have exclusive dominium and

imperium over the waters of the San Juan River from its origin in the
lake to its mouth at the Atlantic Ocean ; the Republic of Costa Rica
shall however have a perpetual right of free navigation on the said
waters between the mouth of the river and a point located three Eng-
lish miles below Castillo Viejo, [con objetos de comercio], whether

with Nicaragua or with the interior of Costa Rica by the rivers San
Carlos or Sarapiquí or any other waterway starting from the section
of the bank of the San Juan established as belonging to that Repub -
lic. The vessels of both countries may land indiscriminately on either
bank of the section of the river where navigation is common, without

paying any taxes, unless agreed by both Governments.” (Translation
from the Spanish original as reproduced in Dispute regarding Naviga‑

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tional and Related Rights (Costa Rica v. Nicaragua), Judgment,
I.C.J. Reports 2009, p. 236, para. 44: “La República de Nicaragua

tendrá exclusivamente el dominio y sumo imperio sobre las aguas del
río de San Juan desde su salida del Lago, hasta su desembocadura en
el Atlántico ; pero la República de Costa Rica tendrá en dichas aguas
los derechos perpetuos de libre navegación, desde la expresada desem ‑
bocadura hasta tres millas inglesas antes de llegar al Castillo Viejo, con

objetos de comercio, ya sea con Nicaragua ó al interior de Costa Rica,
por los ríos de San Carlos ó Sarapiquí, ó cualquiera otra vía procedente
de la parte que en la ribera del San Juan se establece corresponder á
esta República. Las embarcaciones de uno ú otro país podrán indistin ‑
tamente atracar en las riberas del río en la parte en que la navegaci▯ón

es común, sin cobrarse ninguna clase de impuestos, á no ser que se▯
establezcan de acuerdo entre ambos Gobiernos.” )

The Cleveland Award contains some references to Costa Rica’s rights of
navigation that were quoted above (see paragraph 116). In its Judgment
in Dispute regarding Navigational and Related Rights (Costa Rica v. Nica‑
ragua), the Court noted that :

“two types of private navigation are certainly covered by the right off
free navigation pursuant to Article VI of the 1858 Treaty: the navi-

gation of vessels carrying goods intended for commercial transac -
tions; and that of vessels carrying passengers who pay a price other
than a token price (or for whom a price is paid) in exchange for the
service thus provided” ( I.C.J. Reports 2009, p. 245, para. 73).

While the express language of Article VI of the 1858 Treaty only consid-
ered navigation for purposes of commerce, the Court also observed that :

“it cannot have been the intention of the authors of the 1858 Treaty
to deprive the inhabitants of the CostaRican bank of the river, where

that bank constitutes the boundary between the two States, of the
right to use the river to the extent necessary to meet their essential
requirements, even for activities of a non -commercial nature, given
the geography of the area” (ibid., p. 246, para. 79).

In the operative part of the same Judgment, the Court found that :

“the inhabitants of the Costa Rican bank of the San Juan River have
the right to navigate on the river between the riparian communities
for the purposes of the essential needs of everyday life which require
expeditious transportation” (ibid., p. 270, para. 156 (1) (f)).

134. Costa Rica includes among the alleged breaches of its rights of
navigation the enactment by Nicaragua of Decree No. 079-2009 of

1 October 2009, concerning navigation on the San Juan River. The inter -
pretation of this decree is controversial between the Parties : Costa Rica

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considers that the decree is of general application, whereas Nicaragua
contends that it applies only to tourist boats. While it is clear that tfhe

decree should be consistent with Article VI of the 1858 Treaty as inter -
preted by the Court, the Court observes that none of the instances of
interference with Costa Rica’s rights of navigation specifically alleged by
Costa Rica relates to the application of Decree No. 079-2009. The Court
is therefore not called upon to examine this decree.
135. Costa Rica alleges that breaches of its rights of navigation

occurred in five instances. Nicaragua emphasizes the small number of
alleged breaches, but does not contest two of those incidents. In the fifrst
one, in February 2013, a riparian farmer and his uncle were detained forf
several hours at a Nicaraguan army post and subjected to humiliating
treatment. This incident is set out in an affidavit. In the second incifdent,

in June 2014, a Costa Rican property owner and some members of a local
agricultural co-operative were prevented by Nicaraguan agents from nav -
igating the San Juan River. This is supported by five affidavits.

136. The Court finds that Nicaragua did not provide a convincing jus-
tification with regard to Article VI of the 1858 Treaty for the conduct of

its authorities in these two incidents concerning navigation by inhabitafnts
of the Costa Rican bank of the San Juan River. The Court concludes that
the two incidents show that Nicaragua breached Costa Rica’s rights of
navigation on the San Juan River pursuant to the 1858 Treaty. Given this
finding, it is unnecessary for the Court to examine the other incidents f
invoked by Costa Rica.

E. Reparation

137. Costa Rica requests the Court to order Nicaragua to “repeal, by
means of its own choosing, those provisions of the Decree No. 079-2009

and the Regulatory Norms annexed thereto of 1 October 2009 which are
contrary to Costa Rica’s right of free navigation under Article VI of the
1858 Treaty of Limits, the 1888 Cleveland Award, and the Court’s Judg -
ment of 13 July 2009” and to cease all dredging activities in the San Juan
River pending the fulfilment of certain conditions (final submissions, f
para. 3 (a) and (b)).

Costa Rica moreover asks the Court to order Nicaragua to :

“make reparation in the form of compensation for the material dam-

age caused to Costa Rica, including but not limited to: (i) damage
arising from the construction of artificial caños and destruction of
trees and vegetation on the ‘disputed territory’; (ii) the cost of the
remediation measures carried out by Costa Rica in relation to those
damages . . .; the amount of such compensation to be determined in

a separate phase of these proceedings” ( ibid., para. 3 (c)).

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The Court is further requested to order Nicaragua to “provide satisfafc -
tion so [as] to achieve full reparation of the injuries caused to Costa Rica

in a manner to be determined by the Court” (final submissions,
para. 3 (d)) and to “provide appropriate assurances and guarantees of
non-repetition of Nicaragua’s unlawful conduct, in such a form as the
Court may order” (ibid., para. 3 (e)). Costa Rica finally requests an
award of costs that will be considered later in the present section.

138. In view of the conclusions reached by the Court in SectionB s and D
above, the requests made by Costa Rica in its final submissions under
paragraph 3 (a) and (b), concerning the repeal of the DecreeNo. 079-2009
on navigation and the cessation of dredging activities respectively, canfnot
be granted.

139. The declaration by the Court that Nicaragua breached the territo -
rial sovereignty of Costa Rica by excavating three caños and establishing
a military presence in the disputed territory provides adequate satisfacf -
tion for the non -material injury suffered on this account. The same applies
to the declaration of the breach of the obligations under the Court’sf

Order of 8 March 2011 on provisional measures. Finally, the declaration
of the breach of Costa Rica’s rights of navigation in the terms determined
above in Section D provides adequate satisfaction for that breach.

140. The request for “appropriate assurances and guarantees of
non-repetition” was originally based on Nicaragua’s alleged “bad fafith”
in the dredging of the 2010 caño and later on Nicaragua’s infringement of
its obligations under the 2011 Order.

141. As the Court noted in the Navigational and Related Rights case,

“there is no reason to suppose that a State whose act or conduct has fbeen
declared wrongful by the Court will repeat that act or conduct in the
future, since its good faith must be presumed” and therefore assurancfes
and guarantees of non-repetition will be ordered only “in special circum -
stances” (I.C.J. Reports 2009, p. 267, para. 150). While Nicaragua failed

to comply with the obligations under the 2011 Order, it is necessary also
to take into account the fact that Nicaragua later complied with the
requirements, stated in the Order of 22 November 2013, to “refrain from
any dredging and other activities in the disputed territory” and to “fcause
the removal from the disputed territory of any personnel, whether civil -

ian, police or security” (I.C.J. Reports 2013, p. 369, para. 59). It is to be
expected that Nicaragua will have the same attitude with regard to the
legal situation resulting from the present Judgment, in particular in vifew
of the fact that the question of territorial sovereignty over the disputfed
territory has now been resolved.

142. Costa Rica is entitled to receive compensation for the material
damage caused by those breaches of obligations by Nicaragua that have

56

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been ascertained by the Court. The relevant material damage and the
amount of compensation may be assessed by the Court only in separate
proceedings. The Court is of the opinion that the Parties should engage fin
negotiation in order to reach an agreement on these issues. However, if
they fail to reach such an agreement within 12 months of the date of the

present Judgment, the Court will, at the request of either Party, determfine
the amount of compensation on the basis of further written pleadings
limited to this issue.

*

143. Costa Rica also requests the Court to order Nicaragua to :

“pay all of the costs and expenses incurred by Costa Rica in request-
ing and obtaining the Order on provisional measures of 22 November
2013, including, but not limited to, the fees and expenses of

Costa Rica’s counsel and experts, with interest, on a full indemnity
basis” (final submissions, para. 3 (f)).

The special reason for this request is that the proceedings which led tof the
Order of 22 November 2013 were allegedly due to the infringements by
Nicaragua of its obligations under the Order of 8 March 2011.

144. According to Article 64 of the Statute, “[u]nless otherwise decided
by the Court, each party shall bear its own costs”. This Article provfides
that as a rule, costs are not awarded to any of the parties, but gives tfhe

Court the power to order that one of them will pay some or all of the
costs. While the breach by Nicaragua of its obligations under the
2011 Order necessitated Costa Rica engaging in new proceedings on pro -
visional measures, the Court finds that, taking into account the overallf
circumstances of the case, an award of costs to Costa Rica, as the latter

requested, would not be appropriate.

IV. Issues in the NiCaRagua v. Costa R iCa Case

145. The Application filed by Nicaragua on 22 December 2011 (see
paragraph 9 above) concerns the alleged breach by Costa Rica of both

procedural and substantive obligations in connection with the construc -
tion of the road along the San Juan River. The Court will start by consifd-
ering the alleged breach of procedural obligations ; then it will address the
alleged breach of substantive obligations.

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A. The Alleged Breach of Procedural Obligations

1. The alleged breach of the obligation to carry out an environmental

impact assessment

146. According to Nicaragua, Costa Rica breached its obligation
under general international law to assess the environmental impact of the
construction of the road before commencing it, particularly in view of tfhe
road’s length and location.
147. Costa Rica denies the allegation. It argues that the construction

of the road did not create a risk of significant transboundary harm
through the discharge of harmful substances into the San Juan River or
otherwise into Nicaraguan territory, and that there was no risk that thef
river would be materially affected by the relatively insignificant quantfities
of sediment coming from the road.

148. Costa Rica also maintains that it was exempted from the require -
ment to prepare an environmental impact assessment because of the state
of emergency created by Nicaragua’s occupation of Isla Portillos (sefe
paragraphs 63-64 above). First, Costa Rica argues that an emergency can
exempt a State from the requirement to conduct an environmental impact

assessment, either because international law contains a renvoi to domestic
law on this point, or because it includes an exemption for emergency sitfu -
ations. Secondly, Costa Rica submits that the construction of the road
was an appropriate response to the emergency situation because it would f
facilitate access to the police posts and remote communities located alofng

the right bank of the San Juan River, particularly in light of the real frisk
of a military confrontation with Nicaragua, which would require
Costa Rica to evacuate the area. Thus, Costa Rica claims that it could
proceed with its construction works without an environmental impact
assessment.

149. In any event, Costa Rica maintains that, even if it was required
under international law to conduct an environmental impact assessment
in this case, it fulfilled the obligation by carrying out a number of enfvir -
onmental impact studies, including an “Environmental Diagnostic
Assessment” in 2013.

150. In reply, Nicaragua argues that there was no bona fide emergency.
It states that the road is not located near the disputed territory, as dfefined
by the Court’s Order of 8 March 2011, and that the emergency was
declared several months after the beginning of the construction works.
Nicaragua further argues that there is no emergency exemption from the

international obligation to carry out an environmental impact assess -
ment. It points out that Costa Rica improperly seeks to rely on a declara-
tion of emergency made under its domestic law to justify its failure to
perform its international law obligations.

151. Finally, Nicaragua points out that the environmental impact
studies produced by Costa Rica after the bulk of the construction work

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had been completed do not constitute an adequate environmental impact
assessment. As a consequence, it asks the Court to declare that CostaRica

should not undertake any future development in the area without an
appropriate environmental impact assessment.
152. Following the lines of argument put forward by the Parties, the
Court will first examine whether Costa Rica was under an obligation to
carry out an environmental impact assessment under general interna -

tional law. If so, the Court will assess whether it was exempted from thfe
said obligation or whether it complied with that obligation by carrying f
out the Environmental Diagnostic Assessment and other studies.

*

153. The Court recalls (see paragraph 104 above) that a State’s obliga-
tion to exercise due diligence in preventing significant transboundary
harm requires that State to ascertain whether there is a risk of signififcant
transboundary harm prior to undertaking an activity having the potentialf
adversely to affect the environment of another State. If that is the casfe,

the State concerned must conduct an environmental impact assessment.
The obligation in question rests on the State pursuing the activity.
Accordingly, in the present case, it fell on Costa Rica, not on Nicaragua,
to assess the existence of a risk of significant transboundary harm priofr to
the construction of the road, on the basis of an objective evaluation off all

the relevant circumstances.

154. In the oral proceedings, counsel for Costa Rica stated that a pre -
liminary assessment of the risk posed by the road project was undertakenf
when the decision to build the road was made. According to Costa Rica,
this assessment took into account the nature of the project and its likefly

impact on the river, and concluded that the road posed no risk of signifif-
cant harm. In support of this claim, Costa Rica emphasized the modest
scale of the works, that the road was clearly not a highway, that some off
it was constructed on pre -existing tracks, and that the only possible risk
was the contribution of sediment by the road to a river that already carf -

ried a heavy sediment load.
The Court observes that to conduct a preliminary assessment of the
risk posed by an activity is one of the ways in which a State can ascertfain
whether the proposed activity carries a risk of significant transboundarfy
harm. However, Costa Rica has not adduced any evidence that it actually

carried out such a preliminary assessment.
155. In evaluating whether, as of the end of 2010, the construction of
the road posed a risk of significant transboundary harm, the Court will f
have regard to the nature and magnitude of the project and the context ifn
which it was to be carried out.
First, the Court notes that, contrary to Costa Rica’s submission,

the scale of the road project was substantial. The road, which is
nearly 160 km long, runs along the river for 108.2 km (see sketch -map

59

5 Ord 1088.indb 115 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 721

No. 2 above). Approximately half of that stretch is completely new con -
struction.

Secondly, the Court notes that, because of the planned location of the
road along the San Juan River, any harm caused by the road to the sur -
rounding environment could easily affect the river, and therefore Nicaraf-
gua’s territory. The evidence before the Court shows that approximatefly
half of the stretch of road following the San Juan River is situated witfhin

100 metres of the river bank ; for nearly 18 km it is located within
50 metres of the river ; and in some stretches it comes within 5 metres of
the right bank of the river. The location of the road in such close proxfim -
ity to the river and the fact that it would often be built on slopes, rifsked
increasing the discharge of sediment into the river. Another relevant fafc-
tor in assessing the likelihood of sedimentation due to erosion from thef

road is that almost a quarter of the road was to be built in areas that fwere
previously forested. The possibility of natural disasters in the area cafused
by adverse events such as hurricanes, tropical storms and earthquakes,
which would increase the risk of sediment erosion, must equally be takenf
into consideration.

Thirdly, the geographic conditions of the river basin where the road
was to be situated must be taken into account. The road would pass
through a wetland of international importance in Costa Rican territory
and be located in close proximity to another protected wetland — the
Refugio de Vida Silvestre Río San Juan — situated in Nicaraguan terri -

tory. The presence of Ramsar protected sites heightens the risk of signiffi-
cant damage because it denotes that the receiving environment is
particularly sensitive. The principal harm that could arise was the possfi -
ble large deposition of sediment from the road, with resulting risks to fthe
ecology and water quality of the river, as well as morphological changesf.

156. In conclusion, the Court finds that the construction of the road by
Costa Rica carried a risk of significant transboundary harm. Therefore,
the threshold for triggering the obligation to evaluate the environmentafl
impact of the road project was met.

*

157. The Court now turns to the question of whether Costa Rica was
exempted from its obligation to evaluate the environmental impact of the
road project because of an emergency. First, the Court recalls its holding

that “it is for each State to determine in its domestic legislation ofr in the
authorization process for the project, the specific content of the envirfon -
mental impact assessment required in each case”, having regard to varfi -
ous factors (see paragraph 104 above, quoting Pulp Mills on the River
Uruguay (Argentina v. Uruguay), Judgment, I.C.J. Reports 2010 (I),
p. 83, para. 205). The Court observes that this reference to domestic law

does not relate to the question of whether an environmental impact
assessment should be undertaken. Thus, the fact that there may be an

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emergency exemption under Costa Rican law does not affect Costa Rica’s
obligation under international law to carry out an environmental impact

assessment.

158. Secondly, independently of the question whether or not an emer -
gency could exempt a State from its obligation under international law tfo
carry out an environmental impact assessment, or defer the execution of

this obligation until the emergency has ceased, the Court considers thatf,
in the circumstances of this case, Costa Rica has not shown the existence
of an emergency that justified constructing the road without undertakingf
an environmental impact assessment. In fact, completion of the project
was going to take, and is indeed taking, several years. In addition, whefn
Costa Rica embarked upon the construction of the road, the situation in

the disputed territory was before the Court, which shortly thereafter
issued provisional measures. Although Costa Rica maintains that the
construction of the road was meant to facilitate the evacuation of the afrea
of Costa Rican territory adjoining the San Juan River, the Court notes
that the road provides access to only part of that area and thus could

constitute a response to the alleged emergency only to a limited extent.f
Moreover, Costa Rica has not shown an imminent threat of military con -
frontation in the regions crossed by the road. Finally, the Court notes f
that the Executive Decree proclaiming an emergency was issued by
Costa Rica on 21 February 2011, after the works on the road had begun.

159. Having thus concluded that, in the circumstances of this case,
there was no emergency justifying the immediate construction of the roadf,
the Court does not need to decide whether there is an emergency exemp -
tion from the obligation to carry out an environmental impact assessmentf
in cases where there is a risk of significant transboundary harm.

It follows that Costa Rica was under an obligation to conduct an envir-
onmental impact assessment prior to commencement of the construction
works.

*

160. Turning now to the question of whether Costa Rica complied
with its obligation to carry out an environmental impact assessment, the
Court notes that Costa Rica produced several studies, including an Envir-
onmental Management Plan for the road in April 2012, an Environmen -

tal Diagnostic Assessment in November 2013, and a follow -up study
thereto in January 2015. These studies assessed the adverse effects that
had already been caused by the construction of the road on the environ -
ment and suggested steps to prevent or reduce them.

161. In its Judgment in the Pulp Mills case, the Court held that the

obligation to carry out an environmental impact assessment is a continu -
ous one, and that monitoring of the project’s effects on the environmfent

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shall be undertaken, where necessary, throughout the life of the projectf
(I.C.J. Reports 2010 (I), pp. 83-84, para. 205). Nevertheless, the obliga -

tion to conduct an environmental impact assessment requires an ex ante
evaluation of the risk of significant transboundary harm, and thus “afn
environmental impact assessment must be conducted prior to the imple -
mentation of a project” (ibid., p. 83, para. 205). In the present case,
Costa Rica was under an obligation to carry out such an assessment prior

to commencing the construction of the road, to ensure that the design
and execution of the project would minimize the risk of significant tranfs-
boundary harm. In contrast, Costa Rica’s Environmental Diagnostic
Assessment and its other studies were post hoc assessments of the environ-
mental impact of the stretches of the road that had already been built. f
These studies did not evaluate the risk of future harm. The Court notes f

moreover that the Environmental Diagnostic Assessment was carried out
approximately three years into the road’s construction.
162. For the foregoing reasons, the Court concludes that Costa Rica
has not complied with its obligation under general international law to f
carry out an environmental impact assessment concerning the construc -

tion of the road.

2. The alleged breach of Article 14 of the Convention on Biological Diversity

163. Nicaragua submits that Costa Rica was required to carry out an

environmental impact assessment by Article 14 of the Convention on Bio-
logical Diversity. Costa Rica responds that the provision at issue con -
cerns the introduction of appropriate procedures with respect to projectfs
that are likely to have a significant adverse effect on biological diversity.
It claims that it had such procedures in place and that, in any event, tfhey

do not apply to the construction of the road, as it was not likely to hafve
a significant adverse effect on biological diversity.

164. The Court recalls that the provision reads, in relevant part :

“Each Contracting Party, as far as possible and as appropriate,
shall: (a) Introduce appropriate procedures requiring environmental
impact assessment of its proposed projects that are likely to have

significant adverse effects on biological diversity with a view to avoid -
ing or minimizing such effects and, where appropriate, allow for pub-
lic participation in such procedures.”

The Court considers that the provision at issue does not create an obligfa-
tion to carry out an environmental impact assessment before undertaking f
an activity that may have significant adverse effects on biological divefr -
sity. Therefore, it has not been established that Costa Rica breached Arti-

cle 14 of the Convention on Biological Diversity by failing to conduct an
environmental impact assessment for its road project.

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3. The alleged breach of an obligation to notify and consult

165. Nicaragua contends that Costa Rica breached its obligation to
notify, and consult with, Nicaragua in relation to the construction workfs.

Nicaragua founds the existence of such obligation on three grounds, namely,
customary international law, the 1858 Treaty, and the Ramsar Con -
vention. The Court will examine each of Nicaragua’s arguments in turn.

*

166. In Nicaragua’s view, Costa Rica should have notified it of the
road project and should have consulted with it, as Costa Rica had every
reason to believe that the construction of the road risked causing signifi -
cant transboundary harm. According to Nicaragua, the alleged emer -

gency did not exempt Costa Rica from this obligation.
167. For Costa Rica, the relevant threshold of “risk of significant
adverse impact” was not met in this case. Moreover, Costa Rica claims to
have invited Nicaragua to engage in consultations, but Nicaragua did notf
do so. In any event, according to Costa Rica, Nicaragua is prevented
from relying on the obligation to notify since it has itself created thef

emergency to which Costa Rica had to respond by constructing the road.

168. The Court reiterates its conclusion that, if the environmental
impact assessment confirms that there is a risk of significant transbounfd -
ary harm, a State planning an activity that carries such a risk is requifred,

in order to fulfil its obligation to exercise due diligence in preventinfg sig -
nificant transboundary harm, to notify, and consult with, the potentiallfy
affected State in good faith, where that is necessary to determine the
appropriate measures to prevent or mitigate that risk (see paragraph 104
above). However, the duty to notify and consult does not call for exam -

ination by the Court in the present case, since the Court has established
that Costa Rica has not complied with its obligation under general inter -
national law to perform an environmental impact assessment prior to the f
construction of the road.

*

169. Nicaragua further asserts the existence of an obligation to notify
under the 1858 Treaty. In its 2009 Judgment in the Navigational Rights
case, the Court held that Nicaragua has an obligation to notify CostaRica

of its regulations concerning navigation on the river. According to Nicaf-
ragua, since the construction of the road affects Nicaragua’s navigatfional
rights, the same reasoning applies a fortiori in this case.

170. For Costa Rica, Nicaragua’s reference to the 1858 Treaty is mis-

placed, since the Treaty does not impose on Costa Rica an obligation to

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notify Nicaragua if Costa Rica undertakes infrastructure works on its
own territory.

171. The Court recalls its finding in the 2009 Judgment that Nicara -
gua’s obligation to notify Costa Rica under the 1858 Treaty arises,
amongst other factors, by virtue of Costa Rica’s rights of navigation
on the river, which is part of Nicaragua’s territory (Dispute regarding
Navigational and Related Rights (Costa Rica v. Nicaragua), Judgment,

I.C.J. Reports 2009, pp. 251-252, paras. 94-97). In contrast, the
1858 Treaty does not grant Nicaragua any rights on Costa Rica’s terri-
tory, where the road is located. Therefore, no obligation to notify Nicafra -
gua with respect to measures undertaken on Costa Rica’s territory arises.
The Court concludes that the 1858 Treaty did not impose on Costa Rica
an obligation to notify Nicaragua of the construction of the road.

*

172. Lastly, Nicaragua relies on Article 3, paragraph 2, and on Arti -

cle 5 of the Ramsar Convention (see paragraphs 109-110 above) as impos-
ing an obligation of notification and consultation upon the Contracting f
Parties. In the Court’s view, Nicaragua has not shown that, by constrfuct-
ing the road, Costa Rica has changed or was likely to change the eco-
logical character of the wetland situated in its territory. Moreover,

contrary to Nicaragua’s contention, on 28 February 2012 Costa Rica
notified the Ramsar Secretariat about the stretch of the road that passefs
through the Humedal Caribe Noreste. Therefore, the Court concludes that
Nicaragua has not shown that Costa Rica breached Article 3, para -
graph 2, of the Ramsar Convention. As regards Article 5 of the Ramsar
Convention, the Court finds that this provision creates no obligation for

Costa Rica to consult with Nicaragua concerning a particular project it is
undertaking, in this case the construction of the road (see also para -
graph 110 above).

*

173. In conclusion, the Court finds that Costa Rica failed to comply
with its obligation to evaluate the environmental impact of the construcf-
tion of the road. Costa Rica remains under an obligation to prepare an
appropriate environmental impact assessment for any further works on

the road or in the area adjoining the San Juan River, should they carry a
risk of significant transboundary harm. Costa Rica accepts that it is under
such an obligation. There is no reason to suppose that it will not take f
note of the reasoning and conclusions in this Judgment as it conducts anfy
future development in the area, including further construction works on f

the road. The Court also notes Nicaragua’s commitment, made in the
course of the oral proceedings, that it will co -operate with Costa Rica in

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assessing the impact of such works on the river. In this connection, thef
Court considers that, if the circumstances so require, Costa Rica will have

to consult in good faith with Nicaragua, which is sovereign over the Sanf
Juan River, to determine the appropriate measures to prevent significantf
transboundary harm or minimize the risk thereof.

B. Alleged Breaches of Substantive Obligations

174. The Court now turns to the examination of the alleged violations
by Costa Rica of its substantive obligations under customary interna -
tional law and the applicable international conventions. In particular, f
Nicaragua claims that the construction of the road caused damage to the f
San Juan River, which is under Nicaragua’s sovereignty according to the

1858 Treaty. Thus, in Nicaragua’s view, Costa Rica breached the obliga-
tion under customary international law not to cause significant trans -
boundary harm to Nicaragua, the obligation to respect the territorial
integrity of Nicaragua and treaty obligations regarding the protection off
the environment.

175. Over the past four years, the Parties have presented to the Court
a vast amount of factual and scientific material in support of their resfpec-
tive contentions. They have also submitted numerous reports and studies f
prepared by experts and consultants commissioned by each of them on
questions such as technical standards for road construction ; river mor -

phology ; sedimentation levels in the San Juan River, their causes and
effects; the ecological impact of the construction of the road ; and the
status of remediation works carried out by Costa Rica. Some of these
specialists have also appeared before the Court to give evidence in theifr
capacity as experts pursuant to Articles 57 and 64 of the Rules of Court.

176. It is the duty of the Court, after having given careful consider -
ation to all the evidence in the record, to assess its probative value, fto
determine which facts must be considered relevant, and to draw conclu -
sions from them as appropriate. In keeping with this practice, the Courtf
will make its own determination of the facts, on the basis of the totalifty

of the evidence presented to it, and it will then apply the relevant rulfes of
international law to those facts which it has found to be established (fPulp
Mills on the River Uruguay (Argentina v. Uruguay), Judgment, I.C.J.
Reports 2010 (I), p. 72, para. 168).

1.The alleged breach of the obligation not to cause significant transboundary
harm to Nicaragua

177. Nicaragua claims that the construction works resulted in the
dumping of large quantities of sediment into the San Juan River, in par-
ticular because Costa Rica’s disregard of basic engineering principles led

to significant erosion. For example, Costa Rica carried out extensive
deforestation in areas adjacent to the river and earthmoving activities

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that led to the creation of unstable cuts and fills in the river’s prfoximity.
Moreover, the road builders left piles of earth exposed to rainfall and f

failed to construct proper drainage systems and stream crossings so as tfo
avoid erosion. Furthermore, Nicaragua maintains that the stretch of roadf
along the San Juan River is situated too close to the river — nearly half
of it was built within 100 metres of the river, and parts of it even within
5 metres of the river bank — or on steep slopes, thereby increasing the

delivery of sediment to the river. Nicaragua’s main expert opined that
erosion is particularly severe in the 41.6 km stretch of the road containing
the steepest sections, situated between a point denominated “Marker II”
(the western point from which the right bank of the San Juan marks the
boundary with Nicaragua) and Boca San Carlos (at the junction of the
San Juan and San Carlos Rivers ; see sketch-map No. 2 above).

178. According to Nicaragua, the delivery of these large quantities of
sediment to the San Juan River caused an increase in sediment concentra-
tions in the river, which are already unnaturally elevated. It argues thfat

this increase, in and of itself, produced harm to the river, as sedimentf is a
pollutant, and that it had a number of adverse effects. First, it broughft
about changes in the river morphology, as large quantities of the sedi -
ment eroded from the road accumulated on the bed of the Lower
San Juan, thereby exacerbating the problems for navigation in this stretch

of the river and rendering additional dredging necessary to restore the f
navigability of the channel. Moreover, sediment eroded from the road
created large deltas along the Costa Rican bank of the river that obstruct
navigation. Secondly, Nicaragua argues that sediment eroded from the
road caused harm to the river’s water quality and ecosystem. Thirdly,f
Nicaragua alleges that the construction of the road has had an adverse

impact on tourism and the health of the river’s riparian communities.f In
addition, Nicaragua maintains that Costa Rica’s continuing failure to
comply with road construction standards exposes Nicaragua to future
harm, and that Costa Rica has failed to take appropriate remediation
measures. Nicaragua further contends that additional risks derive from

the possibility of spills of toxic materials into the river, the furtherf devel
opment of the Costa Rican bank of the river and the likelihood of natural
disasters caused by adverse events such as hurricanes, tropical storms afnd
earthquakes.
179. For its part, Costa Rica argues that the construction of the road

has not caused any harm to Nicaragua. According to Costa Rica, erosion
is a natural process and sediment is not a pollutant. It contends that
Nicaragua has not adduced any evidence of actual harm to the river, let f
alone significant harm. In addition, Costa Rica argues that the road’s
sediment contribution is tiny compared to the river’s existing sediment
load. It also recalls that, since 2012, it has carried out remediation wforks

to mitigate erosion at slopes and watercourse crossings (such as slope -
terracing; digging drainage channels ; installing cross -drains on the road ;

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constructing sediment traps ; and replacing log bridges with modular
bridges), with a view to further reducing the quantity of sediment fromf

the road that reaches the San Juan River.

180. In order to pronounce on Nicaragua’s allegations, the Court will
first address the Parties’ arguments on the contribution of sediment ffrom

the road to the river ; then it will examine whether the road -derived sedi-
ment caused significant harm to Nicaragua.

(a) The contribution of sediment from the road to the river

181. The Parties agree that sediment eroded from the road is delivered
to the river, but disagree considerably as to the actual volume.

182. Nicaragua argues that the most direct and reliable method to
assess the total amount of sediment contributed from the road is to estif -
mate the volume of sediment entering the river from all the sites along the
road that are subject to erosion. It submits, based on its main expert’fs
estimates, that the total road-derived sediment reaching the river amounts

to approximately 190,000 to 250,000 tonnes per year, including sediment
eroded from the access roads that connect the road to inland areas. Nica -
ragua further submits that the volume of sediment in the river due to thfe
construction of the road would increase by a factor of at least ten durifng
a tropical storm or a hurricane.

183. Costa Rica challenges the estimates of road -derived sediment put
forward by Nicaragua. In particular, it argues, relying on its main expefrt’s
evidence, that Nicaragua’s experts over -estimated the areas subject to
erosion, which they could not measure directly because the road is in

Costa Rica’s territory. It adds that Nicaragua’s estimates are inflatefd by
the inclusion of access roads, which do not contribute any appreciable
quantities of sediment to the San Juan River. According to Costa Rica,
the sediment contribution from the road is approximately 75,000 tonnes
per year. In Costa Rica’s view, even this figure is a significant over -

estimate because it does not take into account the effects of mitigationf
works recently carried out. Finally, Costa Rica argues that Nicaragua’s
experts have overstated the risk of unprecedented rainfall and the impacft
on sediment loads in the river as a result of hurricanes or tropical stofrms.

184. Costa Rica further points out that the most direct and reliable
method for measuring the road’s impact on sediment concentrations in f
the San Juan River would have been for Nicaragua, which is sovereign
over the river, to carry out a sampling programme. Yet Nicaragua has

not provided measurements of sedimentation and flow levels in the river.
The only empirical data before the Court are two reports of the Nicara -

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guan Institute of Territorial Studies (INETER), which contain measure -
ments of flow rates and suspended sediment concentrations taken at

various locations along the San Juan River in 2011 and 2012. Costa Rica
argues that neither set of measurements shows any impact from the road.

185. Nicaragua replies that a sampling programme would not have
been of assistance to assess the impact of the road -derived sediment

because the baseline sediment load of the San Juan prior to the construc-
tion of the road is unknown.
186. The Court notes that it is not contested that sediment eroded
from the road is delivered to the river. As regards the total volume of f
sediment contributed by the road, the Court observes that the evidence

before it is based on modelling and estimates by experts appointed by thfe
Parties. The Court further observes that there is considerable disagree -
ment amongst the experts on key data such as the areas subject to erosion
and the appropriate erosion rates, which led them to reach different conf-
clusions as to the total amount of sediment contributed by the road. The

Court sees no need to go into a detailed examination of the scientific and
technical validity of the different estimates put forward by the Partiesf’
experts. Suffice it to note here that the amount of sediment in the rivfer
due to the construction of the road represents at most 2 per cent of the
river’s total load, according to Costa Rica’s calculations based on the fig-
ures provided by Nicaragua’s experts and uncontested by the latter (fsee

paragraphs 182-183 above and 188-191 below). The Court will come back
to this point below (see paragraph 194), after considering further argu -
ments by the Parties.

(b) Whether the road‑derived sediment caused significant harm to
Nicaragua

187. The core question before the Court is whether the construction of
the road by Costa Rica has caused significant harm to Nicaragua. The
Court will begin its analysis by considering whether the fact that the tfotal
amount of sediment in the river was increased as a result of the construfc-

tion of the road, in and of itself, caused significant harm to Nicaraguaf.
The Court will then examine whether such increase in sediment concen -
trations caused harm in particular to the river’s morphology, navigatfion
and Nicaragua’s dredging programme ; the water quality and the aquatic
ecosystem; or whether it caused any other harm that may be significant.

(i) Alleged harm caused by increased sediment concentrations in the

river
188. Nicaragua contends that the volume (absolute quantity) of sedi -

ment eroded from the road, irrespective of its precise amount, polluted f
the river thereby causing significant harm to Nicaragua. In Nicaragua’fs

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view, the impact of the road’s contribution must be considered takingf
into account the elevated sediment load in the San Juan River which is

allegedly due to deforestation and poor land use practices by Costa Rica.
An expert for Nicaragua estimated the current sediment load to be
approximately 13,700,000 tonnes per year. In this context, Nicaragua
submits that there is a maximum load for sediment in the San Juan, and
that any additional amount of sediment delivered from the road to the

river is necessarily harmful.
189. Costa Rica responds that Nicaragua has not shown that the
San Juan River has a maximum sediment capacity that has been exceeded.
For Costa Rica, the question before the Court is whether the relative
impact of the road -derived sediment on the total load of the San Juan
River caused significant harm. Costa Rica claims that it did not. Accord -

ing to Costa Rica, the San Juan River naturally carries a heavy sediment
load, which is attributable to the geology of the region, and in particular
to the occurrence of earthquakes and volcanic eruptions in the drainage f
area of the river and its tributaries. The volume of sediment contributefd
by the road is insignificant in the context of the river’s total sedifment load

(estimated by Costa Rica at 12,678,000 tonnes per year), of which it rep -
resents a mere 0.6 per cent at most. The road -derived sediment is also
indiscernible considering the high variability in the river’s sedimenft loads
deriving from other sources. Costa Rica adds that, even if Nicaragua’s
figures were to be adopted, the sediment contribution due to the construfc -

tion of the road would still only represent a small proportion, within tfhe
order of 1 -2 per cent, of the total load transported by the San Juan. In
Costa Rica’s view, this amount is too small to have any significant impact.f
190. Nicaragua further argues, drawing on the commentary to the
International Law Commission’s Draft Articles on Prevention of Trans -
boundary Harm from Hazardous Activities, that any detrimental impact

of the construction of the road on the San Juan River need only be sus -
ceptible of being measured to qualify as significant harm. Since the
amount of sediment in the river due to the construction of the road is
measurable, as shown by the fact that both Nicaragua’s and Costa Rica’s
experts have estimated its amount, Nicaragua claims that it caused sig -

nificant harm.
191. Costa Rica retorts that Nicaragua has not shown significant harm
by factual and objective standards. It also argues that, even lacking anf
appropriate baseline, Nicaragua could have measured the impact of the
construction of the road on the river’s sediment concentrations by tafking

its own measurements upstream and downstream of the construction
works. However, Nicaragua failed to do so.

*

192. In the Court’s view, Nicaragua’s submission that any detrimental

impact on the river that is susceptible of being measured constitutes sig -
nificant harm is unfounded. Sediment is naturally present in the river ifn

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large quantities, and Nicaragua has not shown that the river’s sedimefnt
levels are such that additional sediment eroded from the road passes a

sort of critical level in terms of its detrimental effects. Moreover, thfe
Court finds that, contrary to Nicaragua’s submissions, the present cafse
does not concern a situation where sediment contributed by the road
exceeds maximum allowable limits, which have not been determined for
the San Juan River. Thus, the Court is not convinced by Nicaragua’s

argument that the absolute quantity of sediment in the river due to the f
construction of the road caused significant harm per se.

193. The Court will therefore proceed to consider the relative impact
of the road-derived sediment on the current overall sediment load of the
San Juan River. In this regard, the Court notes that the total sediment

load of the San Juan River has not been established. Indeed, Nicaragua
has not provided direct measurements of sediment levels in the river.
Costa Rica, based on its main expert’s report, estimated the river’s total
sediment load to be approximately 12,678,000 tonnes per year using mea -
surements from the Colorado River. Nicaragua has not provided a com -

parable figure, although its expert stated that the current total sedimefnt
load of the San Juan River is roughly 13,700,000 tonnes per year.
194. On the basis of the evidence before it, and taking into account the
estimates provided by the experts of the amount of sediment in the riverf
due to the construction of the road and of the total sediment load of thfe

San Juan River, the Court observes that the road is contributing at
most 2 per cent of the river’s total load. It considers that significant harm
cannot be inferred therefrom, particularly taking into account the high f
natural variability in the river’s sediment loads.

195. In any event, in the Court’s view, the only measurements that are

before it, namely, those contained in the INETER reports from 2011 and
2012, do not support Nicaragua’s claim that sediment eroded from the f
road has had a significant impact on sediment concentrations in the rivefr.
A comparison of the measurements taken in 2011, when most of the road
had not yet been built, and in 2012, when construction works were under f

way, shows that sediment levels in the river are variable, and that tribfu -
taries (particularly the San Carlos and Sarapiquí Rivers) are major
sources of sediment for the San Juan. However, the data do not indicate
a significant impact on sediment levels from the construction of the roafd.
Moreover, the measurements taken at El Castillo and upstream of Boca

San Carlos, which are representative of the steepest stretch of the road,
show no significant impact.

196. In light of the above, the Court concludes that Nicaragua has not
established that the fact that sediment concentrations in the river incrfeased

as a result of the construction of the road in and of itself caused signfifi -
cant transboundary harm.

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(ii) Alleged harm to the river’s morphology, to navigation and to
Nicaragua’s dredging programme

197. The Court will now examine whether the sediment contributed by
the road, which the Court has noted corresponds to at most 2 per cent of

the river’s average total load, caused any other significant harm. Nifcara-
gua’s primary argument on the harm caused by the construction of the f
road concerns the impact of the resulting sediment on the morphology of f
the river, and particularly on the Lower San Juan.
198. The Parties broadly agree that, on the assumption that at “Delta

Colorado” 10 per cent of the waters of the San Juan River flow into the
Lower San Juan, approximately 16 per cent of the suspended sediments
and 20 per cent of the coarse load in the San Juan River would flow into
the Lower San Juan. They also concur that, unlike the much larger Colo -
rado River, the Lower San Juan has no unfilled capacity to transport

sediment. Thus, coarse sediment deposits on the bed of the Lower
San Juan. The Parties’ experts further agree that sediment that settles ofn
the riverbed does not spread evenly, but tends to accumulate in shoals
and sandbars that may obstruct navigation, especially in the dry season.f
They disagree, however, on whether and to what extent the finer sus -

pended sediments are also deposited on the riverbed and, more broadly,
on the effects of the construction of the road on sediment deposition inf
the Lower San Juan.

199. According to Nicaragua’s expert, all of the coarse sediment and
60 per cent of the fine sediment contributed by the road to the Lower
San Juan settle on the riverbed. To maintain the navigability of the river,
Nicaragua is thus required to dredge the fine and coarse sediment that
accumulates in the Lower San Juan. In Nicaragua’s view, in a river that is

already overloaded with sediment such as the Lower San Juan, any addi -
tion of sediment coming from the road causes significant harm to Nicara-
gua because it increases its dredging burden. Furthermore, the accumulatfion
of road -derived sediment reduces the flow of fresh water to the wetlands
downstream, which depend on it for their ecological balance.

200. Nicaragua also argues that sediment eroded from the road cre -
ated “huge” deltas along the river’s channel that obstruct navifgation,
thereby causing significant harm to Nicaragua.

201. Costa Rica responds, relying on the evidence of its main expert,

that the aggradation of the Lower San Juan is an inevitable natural phe -
nomenon that is unrelated to the construction of the road. For Costa Rica,
Nicaragua’s experts also dramatically overestimate the amount of
road-derived sediment that is deposited in the Lower San Juan. First, in
Costa Rica’s view, only coarse sediment accumulates on the riverbed,

whereas most of the fine sediment is washed into the Caribbean Sea.
Secondly, Costa Rica argues that there is no evidence that coarse sediment

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from the road has actually reached the Lower San Juan. Sediment deposi-
tion is not a linear process ; in particular, sediment tends to accumulate in

stretches of the river called “response reaches” and may stay therfe for
years before it is transported further down the channel. Moreover,
Costa Rica points out that the Parties’ estimates are based on a number
of untested assumptions, including estimates of the split of flow and sedi -
ment loads between the Colorado River and the Lower San Juan at

“Delta Colorado”. Costa Rica further argues that Nicaragua’s case on
harm rests on the mistaken assumption that sediment accumulating on
the bed of the Lower San Juan will necessarily need to be dredged.

202. As to the deltas along the Costa Rican bank of the river,

Costa Rica argues that Nicaragua has not shown that they were created
as a result of the construction of the road. For example, satellite imagery
demonstrates that at least two of these deltas pre-date the road. CostaRica
further points out that similar deltas exist on the Nicaraguan bank of tfhe
river. In any event, their impact on the morphology of the river and on f

navigation is insignificant because of their small size relative to the width
of the river.

*

203. The Court notes that Nicaragua has produced no direct evidence
of changes in the morphology of the Lower San Juan or of a deteriora -
tion of its navigability since the construction of the road began. Nicarfa -
gua’s case once again rests on modelling and estimates by its expertsf,
which have not been substantiated by empirical data. The Court observes f
in this regard that there are considerable uncertainties concerning the fvo-l

ume of sediment eroded from the road that has allegedly reached the
Lower San Juan and deposited on its bed. For example, Nicaragua has
not adduced scientific evidence on the division of flow and sediment lfoads
at “Delta Colorado”, but based its estimates on a report of the Costa Rican
Institute of Electricity, which is in turn based on measurements taken

only in the Colorado River.

204. The Court further considers that the expert evidence before it
establishes that the accumulation of sediment is a long -standing natural
feature of the Lower San Juan, and that sediment delivery along the San

Juan is not a linear process. The road -derived sediment is one of a num -
ber of factors that may have an impact on the aggradation of the Lower
San Juan. The Court therefore considers that the evidence adduced by
Nicaragua does not prove that any morphological changes in the Lower
San Juan have been caused by the construction of the road in particular.

205. As to Nicaragua’s claim that the construction of the road has had
a significant adverse impact on its dredging burden, the Court notes thaft

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5 Ord 1088.indb 141 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 734

Nicaragua has adduced no evidence of an increase in its dredging activi -
ties due to the construction of the road. In this connection, the Court falso

recalls that Nicaragua initiated its dredging programme before the con -
struction of the road started (see paragraphs 63-64 above). In any event,
the Court recalls its conclusion that the construction of the road has
caused an increase in sediment concentrations in the river correspondingf
to at most 2 per cent (see paragraph 194 above). The Court observes that
there is no evidence that sediment due to the construction of the road ifs

more likely to settle on the riverbed than sediment from other sources. f
Thus, sediment coming from the road would correspond to at
most 2 per cent of the sediment dredged by Nicaragua in the Lower
San Juan. The Court is therefore not convinced that the road -derived
sediment led to a significant increase in the bed level of the Lower

San Juan or in Nicaragua’s dredging burden.

206. Finally, the Court turns to Nicaragua’s claim that the sediment
deltas along the Costa Rican bank of the river have caused significant
harm to the river’s morphology and to navigation. In the Court’s vfiew,

the photographic evidence adduced by Nicaragua indicates that there are f
deltas on the Costa Rican bank of the river to which the construction of
the road is contributing sediment. The Court observes that Nicaragua
submitted that in the steepest stretch of the road there are eight “hfuge”
deltas but was not able to specify the total number of deltas allegedly fcre-
ated as a consequence of the construction of the road. The Court further

notes that satellite images in the record show that at least two of thesfe
deltas pre-date the road. In any event, the Court considers that Nicara -
gua has not presented sufficient evidence to prove that these deltas, wfhich
only occupy the edge of the river’s channel on the Costa Rican bank,
have had a significant adverse impact on the channel’s morphology or fon

navigation.

207. For the foregoing reasons, the Court concludes that Nicaragua
has not shown that sediment contributed by the road has caused signifi -
cant harm to the morphology and navigability of the San Juan River and
the Lower San Juan, nor that such sediment significantly increased Nica -

ragua’s dredging burden.

(iii)Alleged harm to water quality and the aquatic ecosystem

208. The Court will now consider Nicaragua’s contention concerning
harm to water quality and the aquatic ecosystem. In its written pleadingfs,
Nicaragua alleged that the increased sediment concentrations in the rivefr
as a result of the construction of the road caused significant harm to fifsh
species, many of which belong to families that are vulnerable to elevatefd

levels of sediments, to macro -invertebrates and to algal communities in
the river. Furthermore, according to Nicaragua, the road’s sediment

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5 Ord 1088.indb 143 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 735

caused a deterioration in the water quality of the river. To prove harm fto
aquatic organisms and water quality, Nicaragua relied inter alia on an

expert report based on sampling at 16 deltas in the river, which concluded
that both species richness and abundance of macro -invertebrates were
significantly lower on the south bank than on the north bank.

209. During the course of the oral proceedings, Nicaragua’s case
shifted from its prior claim of actual harm to the river’s ecosystem fto a
claim based on the risk of harm. The Parties now agree that there have
been no studies of the fish species in the San Juan River to determine
whether they are vulnerable to elevated levels of sediment. However,
Nicaragua claims that Costa Rica’s Environmental Diagnostic Assess -

ment and the follow-up study carried out in January 2015 by the Tropical
Science Centre (hereinafter “CCT”, by its Spanish acronym) show fthat
the road is harming macro-invertebrates and water quality in the tributar-
ies that flow into the San Juan River. The CCT measured water quality in
Costa Rican tributaries upstream and downstream of the road and

recorded a lower water quality downstream of the road. For Nicaragua,
this demonstrates a risk of harm to the river itself due to the cumulatifve
impact of those tributaries.

210. For Costa Rica, Nicaragua’s case on the impact on fish species
fails due to the lack of evidence of actual harm. Relying on one of its f
experts, Costa Rica argues that it is very likely that species living in the
river are adapted to conditions of high and variable sediment loads and f
are highly tolerant of such conditions. As to macro -invertebrates and
water quality, Costa Rica submits that the CCT study shows no signifi -

cant impact. In any event, its results are based on sampling on small trfib-
utary streams in Costa Rica, and cannot be transposed to the much larger
San Juan River. Costa Rica further argues that the expert report adduced
by Nicaragua does not provide sufficient support for Nicaragua’s clafim
that the construction of the road has had an adverse impact on

macro -invertebrates living in deltas along the south bank of the river.

*

211. The Court observes that Nicaragua has not presented any evi -
dence of actual harm to fish in the San Juan River, nor has it identified
with precision which species of fish have allegedly been harmed by the
construction of the road.

212. In the Court’s view, the Environmental Diagnostic Assessment
relied upon by Nicaragua only shows that the construction of the road

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5 Ord 1088.indb 145 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 736

has had a localized impact on macro-invertebrate communities and water
quality in small Costa Rican streams draining into the San Juan River.

However, the Court is not persuaded that the results of the Environmen -
tal Diagnostic Assessment and the follow -up study can be transposed to
the San Juan River, which has an average width of nearly 300 metres. As
regards the expert report submitted by Nicaragua, the Court finds it diff -
ficult to attribute any differences in macro -invertebrate richness and

abundance between the north and the south banks of the river to the
construction of the road alone, as opposed to other factors such as the f
size of the catchment area and the nutrient levels therein.

213. On the basis of the foregoing considerations, the Court finds that

Nicaragua has not proved that the construction of the road caused sig -
nificant harm to the river’s ecosystem and water quality.

(iv) Other alleged harm

214. Nicaragua also alleges that the construction of the road has had
an adverse impact on the health of the communities along the river, whicfh
is dependent upon the health of the river itself. Furthermore, in Nicaraf -
gua’s view, the road significantly affected the area’s tourism potfential as

it has a negative visual impact on the natural landscape. Finally, Nicarfa-
gua argues that, in addition to the transboundary harm that the road has
already caused, it poses a significant risk of future transboundary harmf.
According to Nicaragua, additional risks derive from the possibility
of spills of toxic materials into the river whenever hazardous substances
are transported on the road, and from any further development of the

right bank of the river, such as increased agricultural and commercial
activities.
215. Costa Rica responds that Nicaragua did not adduce any evidence
of actual impact on tourism or on the health of riparian communities.
Moreover, it did not explain the legal basis of its claims. Furthermore,f

Costa Rica contends that Nicaragua’s arguments on the risk of toxic
spills in the river are based entirely on speculation : Costa Rica’s 1995
Regulations for the Ground Transportation of Hazardous Material pro -
vide that hazardous substances can only be transported on authorized
roads, and Route 1856 is not one of them.

*

216. The Court finds that Nicaragua did not substantiate its conten -
tions regarding harm to tourism and health. The Court further observes
that Nicaragua’s arguments concerning the risk of toxic spills into tfhe
river and of further development of the Costa Rican bank of the river are

speculative and fail to show any harm. Therefore, these arguments fail.

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5 Ord 1088.indb 147 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 737

(c) Conclusion

217. In light of the above,the Court concludes that Nicaragua has not

proved that the construction of the road caused it significant transbound -
ary harm. Therefore, Nicaragua’s claim that Costa Rica breached its sub-
stantive obligations under customary international law concerning
transboundary harm must be dismissed.

2. Alleged breaches of treaty obligations

218. Nicaragua further argues that Costa Rica violated substantive
obligations contained in several universal and regional instruments. Firfst,
it contends that Costa Rica breached Article 3, paragraph 1, of the
Ramsar Convention. Secondly, it argues that Costa Rica acted contrary

to the object and purpose of the 1990 Agreement over the Border Pro -
tected Areas between Nicaragua and Costa Rica (“SI -A-PAZ Agree -
ment”). Thirdly, Nicaragua alleges that, by its activities, Costa Rica
violated Articles 3 and 8 of the Convention on Biological Diversity.
Fourthly, it claims that Costa Rica violated several provisions of the

Convention for the Conservation of the Biodiversity and Protection of
Priority Wilderness Areas in Central America. Fifthly, it alleges viola -
tions of the Central American Convention for the Protection of the Envirf -
onment and the Tegucigalpa Protocol to the Charter of the Organization
of Central American States. Finally, Nicaragua contends that Costa Rica

breached Article 3 of the Regional Agreement on the Transboundary
Movement of Hazardous Wastes, on the ground that it did not adopt and
implement the precautionary approach to pollution problems provided
for in that instrument.

219. In response to these allegations, Costa Rica argues at the outset
that, since Nicaragua failed to prove that the construction of the road f
caused any significant transboundary harm, its contentions must fail.
Costa Rica further points out that the construction of the road does not
touch upon protected Nicaraguan wetlands falling within the Ramsar

Convention. Moreover, it states that Nicaragua has identified no provi -
sion of the SI-A-PAZ Agreement that was allegedly breached. Costa Rica
further maintains that the Central American Convention for the Protec -
tion of the Environment and the Tegucigalpa Protocol are of no relevancef
to the present dispute and that there is no factual basis for Nicaragua’fs

contentions regarding the Regional Agreement on the Transboundary
Movement of Hazardous Wastes.

*

220. The Court notes that both Nicaragua and Costa Rica are parties

to the instruments invoked by Nicaragua. Irrespective of the question of
the binding character of some of the provisions at issue, the Court

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5 Ord 1088.indb 149 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 738

observes that, in relation to these instruments, Nicaragua simply makes f
assertions about Costa Rica’s alleged violations and does not explain how

the “objectives” of the instruments or provisions invoked would have
been breached, especially in the absence of proof of significant harm tof
the environment (see paragraph 217 above). The Court therefore consid -
ers that Nicaragua failed to show that Costa Rica infringed the
above-mentioned instruments.

3. The obligation to respect Nicaragua’s territorial integrity and sovereignty
over the San Juan River

221. Nicaragua further alleges that the deltas created by sediment
eroded from the road are “physical invasions, incursions by Costa Rica

into Nicaragua’s sovereign territory . . . through the agency of sediment”
and that their presence constitutes “trespass” into Nicaragua’sf territory.
Moreover, Nicaragua maintains that the dumping of sediments, soil,
uprooted vegetation and felled trees into the river by Costa Rica poses a
serious threat to the exercise of Nicaragua’s right of navigation on fthe
San Juan, which is based on its sovereignty over the river. Nicaragua

therefore claims that, by its conduct and activities, Costa Rica violated
Nicaragua’s territorial integrity and sovereignty over the San Juan River,
as established by the 1858 Treaty.

222. Costa Rica argues that undertaking road infrastructure works

entirely within its territory does not infringe the boundary delimited bfy
the 1858 Treaty or violate Nicaragua’s sovereignty, nor does it affect
Nicaragua’s right to navigate the San Juan River. Furthermore,
Costa Rica maintains that the 1858 Treaty has no bearing on this case, as
it does not regulate the issues that are at stake here.

223. The Court considers that, whether or not sediment deltas are cre -
ated as a consequence of the construction of the road, Nicaragua’s theory
to support its claim of a violation of its territorial integrity via sediment
is unconvincing. There is no evidence that Costa Rica exercised any
authority on Nicaragua’s territory or carried out any activity thereifn.

Moreover, for the reasons already expressed in paragraphs 203 to 207
above, Nicaragua has not shown that the construction of the road
impaired its right of navigation on the San Juan River. Therefore, Nica -
ragua’s claim concerning the violation of its territorial integrity afnd sov -
ereignty must be dismissed.

C. Reparation

224. Nicaragua requests the Court to adjudge and declare that, by its
conduct, Costa Rica has breached its obligation not to violate Nicara -

gua’s territorial integrity its obligation not to damage Nicaraguan terri -

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5 Ord 1088.indb 151 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 739

tory; and its obligations under general international law and the relevant
environmental treaties (final submissions, para. 1 ; see paragraph 52

above).
In the light of its reasoning above, the Court’s declaration that
Costa Rica violated its obligation to conduct an environmental impact
assessment is the appropriate measure of satisfaction for Nicaragua.

225. Secondly, Nicaragua asks the Court to order that Costa Rica
“[c]ease all its continuing internationally wrongful acts that affectf or are
likely to affect the rights of Nicaragua” (ibid., para. 2 (i)).

The Court considers that Costa Rica’s failure to conduct an environ-
mental impact assessment does not at present adversely affect the rightsf

of Nicaragua nor is it likely further to affect them. Consequently, therfe
are no grounds to grant the remedy requested.

226. Thirdly, Nicaragua requests the Court to order Costa Rica to
restore to the extent possible the situation that existed before the road

was constructed, and to provide compensation for the damage caused
insofar as it is not made good by restitution (ibid., para. 2 (ii) and (iii)).
The Court recalls that restitution and compensation are forms of repara -
tion for material injury. The Court notes that, although Costa Rica did
not comply with the obligation to conduct an environmental impact

assessment, it has not been established that the construction of the road
caused significant harm to Nicaragua or was in breach of other substan -
tive obligations under international law. As such, restoring the originafl
condition of the area where the road is located would not constitute an f
appropriate remedy for Costa Rica’s breach of its obligation to carry out
an environmental impact assessment (see Pulp Mills on the River Uruguay

(Argentina v. Uruguay), Judgment, I.C.J. Reports 2010 (I), p. 103,
para. 271). For the same reasons, the Court declines to grant Nicaragua’s f
claim for compensation.
In view of Nicaragua’s failure to prove that significant harm was
caused, the Court does not need to consider the appointment of an expertf

or committee to evaluate the extent of harm and the chain of causation, f
as Nicaragua suggests.
227. The Court further considers that Nicaragua’s request to order
Costa Rica not to undertake any future development in the border area
without an appropriate environmental impact assessment (final submis -

sions, para. 3 (i)) must be rejected. As the Court stated in paragraph 173
above, Costa Rica’s obligation to conduct an environmental impact
assessment only applies to activities carrying a risk of significant trafns -
boundary harm, and there is no reason to suppose that Costa Rica will
not comply with its obligations under international law, as outlined in f
this Judgment, as it conducts any future activities in the area, includifng

further construction works on the road.

78

5 Ord 1088.indb 153 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 740

228. To conclude, the Court notes that Costa Rica has begun mitiga -

tion works in order to reduce the adverse effects of the construction off the
road on the environment. It expects that Costa Rica will continue to pur-
sue these efforts in keeping with its due diligence obligation to monitofr
the effects of the project on the environment. It further reiterates thef
value of ongoing co -operation between the Parties in the performance of

their respective obligations in connection with the San Juan River.

*
* *

229. For these reasons,

The Court,
(1) By fourteen votes to two,

Finds that Costa Rica has sovereignty over the “disputed territory”, as
defined by the Court in paragraphs 69-70 of the present Judgment ;

in favour : President Abraham; Vice‑President Yusuf; Judges Owada,
Tomka, Bennouna, Cançado Trindade, Greenwood, Xue, Donoghue,
Gaja, Sebutinde, Bhandari, Robinson Judge ad hoc Dugard ;

against: Judge Gevorgian; Judge ad hoc Guillaume ;

(2) Unanimously,

Finds that, by excavating three caños and establishing a military pres -
ence on Costa Rican territory, Nicaragua has violated the territorial sov -

ereignty of Costa Rica;
(3) Unanimously,

Finds that, by excavating two caños in 2013 and establishing a military
presence in the disputed territory, Nicaragua has breached the obligatiofns

incumbent upon it under the Order indicating provisional measures issuedf
by the Court on 8 March 2011 ;

(4) Unanimously,

Finds that, for the reasons given in paragraphs 135-136 of the present
Judgment, Nicaragua has breached Costa Rica’s rights of navigation on
the San Juan River pursuant to the 1858 Treaty of Limits ;

(5) (a) Unanimously,

Finds that Nicaragua has the obligation to compensate Costa Rica for
material damages caused by Nicaragua’s unlawful activities on
Costa Rican territory ;

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5 Ord 1088.indb 155 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 741

(b) Unanimously,

Decides that, failing agreement between the Parties on this matter
within 12 months from the date of this Judgment, the question of com -
pensation due to Costa Rica will, at the request of one of the Parties, be
settled by the Court, and reserves for this purpose the subsequent procef -
dure in the case concerning Certain Activities Carried Out by Nicaragua in

the Border Area (Costa Rica v. Nicaragua);

(c) By twelve votes to four,
Rejects Costa Rica’s request that Nicaragua be ordered to pay costs

incurred in the proceedings ;
in favour : President Abraham; Vice‑President Yusuf; Judges Owada, Ben -
nouna, Cançado Trindade, Xue, Donoghue, Gaja, Bhandari, Robinson,
Gevorgian ; Judge ad hoc Guillaume ;

against: Judges Tomka, Greenwood, Sebutinde Judge;ad hoc Dugard ;

(6) Unanimously,
Finds that Costa Rica has violated its obligation under general interna-

tional law by failing to carry out an environmental impact assessment
concerning the construction of Route 1856 ;

(7) By thirteen votes to three,

Rejects all other submissions made by the Parties.
in favour : President Abraham; Vice‑President Yusuf; Judges Owada,
Tomka, Bennouna, Cançado Trindade, Greenwood, Xue, Donoghue,

Gaja, Sebutinde, Gevorgian Judge ad hoc Guillaume ;
against: Judges Bhandari, Robinson Jud;e ad hoc Dugard.

Done in French and in English, the French text being authoritative, at

the Peace Palace, The Hague, this sixteenth day of December, two thou -
sand and fifteen, in three copies, one of which will be placed in the
archives of the Court and the others transmitted to the Government of
the Republic of Costa Rica and the Government of the Republic of Nica-

ragua, respectively.

(Signed) Ronny Abraham,

President.
(Signed) Philippe Couvreur,

Registrar.

Vice-President Yusuf appends a declaration to the Judgment of the
Court ; JudgeOwada appends a separate opinion to the Judgment of the
Court; Judges Tomka, Greenwood, Sebutifnde and Judge ad hoc

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5 Ord 1088.indb 157 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 742

Dugard append a joint declaration to the Judgment of the Court ; Judge

Cançado Trindade appends a separate opinion to the Judgment of the
Court; Judge Donoghue appends a separate opinion to the Judgment of
the Court ; Judge Bhandari appends a separate opinion to the Judgment
of the Court ; Judge Robinson appends a separate opinion to the
Judgment of the Court ; Judge Gevorgian appends a declaration to the

Judgment of the Court ; Judge ad hoc Guillaume appends a declaration
to the Judgment of the Court ; Judge ad hoc Dugard appends a separate
opinion to the Judgment of the Court.

(Initialled) R.A.

(Initialled)Ph.C.

81

5 Ord 1088.indb 159 19/10/16 12:01

Bilingual Content

COUR INTERNATIONALE DE JUSTICE

RECUEIL DES ARRÊTS,
AVIS CONSULTATIFS ET ORDONNANCES

CERTAINES ACTIVITÉS MENÉES PAR LE NICARAGUA
DANS LA RÉGION FRONTALIÈRE

(COSTA RICA c. NICARAGUA)

et

CONSTRUCTION D’UNE ROUTE AU COSTA RICA

LE LONG DU FLEUVE SAN JUAN

(NICARAGUA c. COSTA RICA)

ARRÊT DU 16 DÉCEMBRE 2015

2015

INTERNATIONAL COURT OF JUSTICE

REPORTS OF JUDGMENTS,
ADVISORY OPINIONS AND ORDERS

CERTAIN ACTIVITIES CARRIED OUT BY NICARAGUA
IN THE BORDER AREA

(COSTA RICA v. NICARAGUA)

and

CONSTRUCTION OF A ROAD IN COSTA RICA

ALONG THE SAN JUAN RIVER

(NICARAGUA v. COSTA RICA)

JUDGMENT OF 16 DECEMBER 2015

5 Ord 1088.indb 1 19/10/16 12:01 Mode officiel de citation :

Certaines activités menées par le Nicaragua dans la région fron▯talière
(Costa Rica c. Nicaragua) et Construction d’une route au Costa Rica
le long du fleuve San Juan (Nicaragua c. Costa Rica),
arrêt, C.I.J. Recueil 2015, p. 665

Officialitation:

Certain Activities Carried Out by Nicaragua in the Border Area
(Costa Rica v. Nicaragua) and Construction of a Road in Costa Rica
along the San Juan River (Nicaragua v. Costa Rica),
Judgment, I.C.J. Reports 2015, p. 665

o
N de vente:
ISSN 0074-4441 Sales number 1088
ISBN 978-92-1-157280-3

5 Ord 1088.indb 2 19/10/16 12:01 16 DÉCEMBRE 2015

ARRÊT

CERTAINES ACTIVITÉS MENÉES PAR LE NICARAGUA
DANS LA RÉGION FRONTALIÈRE

(COSTA RICA c. NICARAGUA)

et

CONSTRUCTION D’UNE ROUTE AU COSTA RICA

LE LONG DU FLEUVE SAN JUAN

(NICARAGUA c. COSTA RICA)

CERTAIN ACTIVITIES CARRIED OUT BY NICARAGUA
IN THE BORDER AREA

(COSTA RICA v. NICARAGUA)

and

CONSTRUCTION OF A ROAD IN COSTA RICA
ALONG THE SAN JUAN RIVER

(NICARAGUA v . COSTA RICA)

16 DECEMBER 2015

JUDGMENT

5 Ord 1088.indb 3 19/10/16 12:01 665

TABLE DES MATIÈRES

Paragraphes

Qualités 1-52

I. Compétence de la Cour 54-55

II. Contexte géographiquef et historique et genèfse des diffé -

rends 56-64

III. Questions en litige efn l’affaire osta RiCa c. iCaRagua 65-144
A. Souveraineté sur le territoire litigieux et violations alléguéefs

de celle-ci 65-99
B. Allégations de violation du droit international de l’environ -

nement 100-120
1. Obligations de nature procédurale 101 -112

a) Allégation de violation de l’obligation d’effectuer une
évaluation de l’impact sur l’environnement 101 -105

b) Allégation de violation d’une obligation de notification
et de consultation 106 -111

c) Conclusion 112
2. Obligations de fond en matière de dommages transfron -

tières 113-120
C. Respect des mesures conservatoires 121 -129

D. Droits de navigation 130 -136
E. Réparations 137 -144

IV. Questions en litige efn l’affaireN iCaRagua c. Costa RiCa 145-228

A. Allégations de violation d’obligations de nature procédurale 146 -173

1. Allégation de violation de l’obligation d’effectuer une éva -
luation de l’impact sur l’environnement 146-162
2. Allégation de violation de l’article 14 de la convention sur

la diversité biologique 163 -164
3. Allégation de violation d’une obligation de notification et

de consultation 165 -172
B. Allégations de violation d’obligations de fond 174 -223

1. Allégation de violation de l’obligation de ne pas causer de
dommage transfrontière important au Nicaragua 177 -217

a) Apport sédimentaire attribuable à la route 181-186

b) Question de savoir si les sédiments produits par la route

ont causé des dommages importants au Nicaragua 187 -216

4

5 Ord 1088.indb 4 19/10/16 12:01 665

TABLE OF CONTENTS

Paragraphs

Chronology of the Procedfure 1-52

I. Jurisdiction of the Coufrt 54 -55

II. Geographical and Historical Context and Origin of the

Disputes 56-64

III. Issues in the osta RiCav. NiCaRagua Case 65-144
A. Sovereignty over the disputed territory and allegedreaches

thereof 65 -99
B. Alleged violations of international environmental law 100 -120

1. Procedural obligations 101 -112

(a) The alleged breach of the obligation to carry out an
environmental impact assessment 101 -105

(b) The alleged breach of an obligation to notify and
consult 106 -111

(c) Conclusion 112
2. Substantive obligations concerning transboundary

harm 113-120
C. Compliance with provisional measures 121 -129

D. Rights of navigation 130 -136
E. Reparation 137 -144

IV. Issues in theN iCaRagua v.C osta RiCaCase 145-228

A. The alleged breach of procedural obligations 146 -173

1. The alleged breach of the obligation to carry out an
environmental impact assessment 146 -162
2. The alleged breach of Article 14 of the Convention on Bio

logical Diversity 163-164
3. The alleged breach of an obligation to notify and

consult 165-172
B. Alleged breaches of substantive obligations 174 -223

1. The alleged breach of the obligation not to cause sign-fi
cant transboundary harm to Nicaragua 177-217

(a) The contribution of sediment from the road to the
river 181-186
(b) Whether the road -derived sediment caused significant

harm to Nicaragua 187-216

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5 Ord 1088.indb 5 19/10/16 12:01 666 certaines activitésf et construction d’unfe route (arrêt)

i) Les dommages qui auraient résulté de la hausse
des concentrations sédimentaires dans le fleuve 188-196
ii) L’atteinte qui aurait été portée à la morphologie

du fleuve, à la navigation et au programme de
dragage du Nicaragua 197-207
iii) L’atteinte qui aurait été portée à la qualité de l’feau

et à l’écosystème aquatique 208-213
iv) Les autres dommages allégués 214-216

c) Conclusion 217
2. Allégations de violation d’obligations d’origine conven -

tionnelle 218-220
3. L’obligation de respecter l’intégrité territoriale du Nicaraf-
gua et sa souveraineté sur le fleuve San Juan 221-223

C. Réparations 224-228

Dispositif 229

5

5 Ord 1088.indb 6 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 666

(i) Alleged harm caused by increased sediment
concentrations in the river 188-196
(ii) Alleged harm to the river’s morphology, to

navigation and to Nicaragua’s dredging pro -
gramme 197-207
(iii) Alleged harm to water quality and the aquatic

ecosystem 208 -213
(iv) Other alleged harm 214-216

(c) Conclusion 217
2. Alleged breaches of treaty obligations 218 -220

3. The obligation to respect Nicaragua’s territorial integrity
and sovereignty over the San Juan River 221-223

C. Reparation 224 -228

Operative Clause 229

5

5 Ord 1088.indb 7 19/10/16 12:01 667

COUR INTERNATIONALE DE JUSTICE

2015 ANNÉE 2015

16 décembre
Rose général 16 décembre 2015
n 150 et 152

CERTAINES ACTIVITÉS MENÉES PAR LE NICARAGUA

DANS LA RÉGION FRONTALIÈRE

(COSTA RICA c. NICARAGUA)

ET

CONSTRUCTION D’UNE ROUTE AU COSTA RICA

LE LONG DU FLEUVE SAN JUAN

(NICARAGUA c. COSTA RICA)

Compétence de la Cour.

* *

Contexte géographique et historique et genèse des différends.
Fleuve San Juan, cours inférieur du San Juan et fleuve Colorado — Isla Calero
et Isla Portillos — Lagune de Harbor Head — Zones humides d’importance inter‑

nationale— Traité de limites de 1858 — Sentence Cleveland — Sentences Alexan‑
der — Dragage du San Juan par le Nicaragua — Activités menées par le Nicara ‑
gua dans la partie septentrionale d’Islallos: dragage d’un chenal (caño) et
établissement d’une présence milita— Construction de la route1856 Juan
Rafael Mora Porras (la route) par le Costa Rica.

* *

Questions en litige en l’affaire Costa Rica c. Nicaragua.
Souveraineté sur le territoire litigieux — Définterritoire litigieux»
Délimitation de la frontière dans le traité de 1858 et dans les▯ sentences Cleveland

et Alexander — Articles II et VI du traité de 1858 devant être lus conjointement —
Souveraineté sur la rive droite du fleuvJuan jusqu’à son embouchure étant
attribuée au Costa Rica — Référence au « premier chenal rencontré » dans la pre

6

5 Ord 1088.indb 8 19/10/16 12:01 667

INTERNATIONAL COURT OF JUSTICE

YEAR 2015 2015

16 December
16 December 2015 General List
Nos.150 and 152

CERTAIN ACTIVITIES CARRIED OUT BY NICARAGUA

IN THE BORDER AREA

(COSTA RICA v. NICARAGUA)

AND

CONSTRUCTION OF A ROAD IN COSTA RICA

ALONG THE SAN JUAN RIVER

(NICARAGUA v. COSTA RICA)

Jurisdiction of the Court.

* *

Geographical and historical context and origin of the disputes.
The San Juan River, Lower San Juan and Colorado —iIsla Calero and
Isla Portillos — Harbor Head La—oWetlands of international impo—tance

1858Treaty of LimitsCleveland Award— Alexander Awards — Dredging of
the San Juan by Nicaragua Activities of Nicaragua in the northern part of
Isla Portillos:dging of a channel (caño) and establishment of a military pres
ence— Construction of Route 1856 Juan Rafael Mora Porras (the road) by ▯
Costa Rica.

* *

Issues in the Costa Rica v. Nicaragua case.
Sovereignty over the disputed territory — Definition of “disputed territory” —
Description of boundary in 1Treaty,leveland and Alexander Award—

ArticlesI and VI of 1858 Treaty to be read together — Sovereignty over right
bank of San Juan River as far as its mouth attributed to Costa Rica — Reference
to “first channel met” in first Alexande— Satellite and aerial images

6

5 Ord 1088.indb 9 19/10/16 12:01 668 certaines activitésf et construction d’unfe route (arrêt)

mière sentence Alexander — Images satellite et aériennes étant insuffisantes pour
établir qu’un caño existait avant les opérations de dragage de 2— Déclara‑
tions sous serment émanant d’agents de l’Etat nicaraguayens é▯tant également
insuffisantes Valeur des éléments de preuve cartographiques et effectivités ▯étant
limitée— Effectivités ne pouvant affecter le titre de souveraineté déco▯ulant du

traité de 1858 et des sentences Cleveland et Alexander — Existence du caño avant
2010 étant contredite par d’autres éléments de preu— Position du Nicaragua
revenant à priver le Costa Rica de sa souveraineté territoriale sur la rive droite du
fleuve SanJuan jusqu’à son embouchure — Rive droite du caño ne correspondant
pas à la frontière — Souveraineté sur le territoire litigieux appartenant au
Costa Rica.

Allégations de violation de la souveraineté du CostRica — Creusement de
trois caños et établissement d’une présence militaire dans le territoire l▯itigieux par
le Nicaragua n’étant pas contestés — Violation de la souveraineté territoriale du
Costa Rica — Obligation de réparation — Absence de violation de l’article IX du
traité de 1858 — Nul besoin d’examiner la question de la violation de l’interdicti▯on

de la menace ou de l’emploi de la force — Nul besoin de rechercher si la conduite
du Nicaragua représente une occupation militaire.

*

Allégations de violation du droit international de l’environnement▯.
Obligations d’ordre procédural — Obligation de procéder à une évaluation de
l’impact sur l’environnement concernant les activités risquant ▯de causer d‑s dom

mages transfrontières importants — Teneur de l’évaluation de l’impact sur
l’environnement dépendant des circonstances propres à chaque ca▯s— Si l’évaluation
confirme un risque de dommage transfrontière important, Etat d’ori▯gine étant
tenu, conformément à son obligation de diligence due, d’informe▯r et de consulter
l’Etat susceptible d’être affecté, lorsque cela est néces▯saire aux fins de définir les

mesures propres à prévenir ou réduire ce risque— Programme de dragage du
Nicaragua n’ayant pas créé de risque de dommage transfrontiè▯re important—
Nicaragua n’étant pas tenu d’effectuer une évaluation de l’▯impact transfrontière
sur l’environnement Absence, faute de risque de dommage transfrontière impor
tant, d’obligation de notification et de consultation découlant du▯ droit international

général— Absence d’obligation conventionnelle de notification et de consultat▯ion
en l’espèce — Cour concluant que le Nicaragua n’a manqué à aucune obligation▯
d’ordre procédural.
Obligations de fond — Obligations spécifiques concernant le fleuve SaJuan
découlant du traité de 1858 tel qu’interprété par la sent▯ence Clevelandga ‑

tion, en droit coutumier, de faire preuve de la diligence requise en vue▯ de prévenir
les dommages transfrontières importants Nul besoin d’examiner la question de
l’articulation entre ces obligations, aucun dommage n’ayant été▯ établi — Absence
de preuve montrant que le dragage du San Juan inférieur a porté préjudice à la
zone humide costa‑ricienne — Allégation selon laquelle le programme de dragage
aurait entraîné une diminution importante du débit du fleuve Co▯lorado n’ayant pas

été prouvée — Détournement des eaux éventuellement provoqué par le dragage d▯u
San Juan inférieur n’ayant pas perturbé gravement la navigation sur▯ le Colorado
ni causé d’une autre manière des dommages au CostaRica — Cour concluant que
le Nicaragua n’a manqué à aucune obligation de fond.

*

7

5 Ord 1088.indb 10 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 668

insufficient to prove caño existed prior to dredging in 2010 — Affidavits of Nica‑
raguan State officials also insufficientgnificance of map evidence and effec-
tivités limited Effectivités cannot affect title to sovereignty resulting from
1858 Treaty and Cleveland and Alexander Awards — Existence of caño prior to
2010 contradicted by other evidence — Nicaragua’s claim would prevent

Costa Rica from enjoying territorial sovereignty over the right bank of the Sa▯n
Juan as far as its mouth — Right bank of the caño not part of the boundary—
Sovereignty over disputed territory belongs to Costa Rica.

Alleged breaches of Costa Rica’s sovereignty — Uncontested that Nicaragua
excavated three caños and established a military presence in disputed territory —
Costa Rica’s territorial sovereignty breached — Obligation to make reparation —
No violation of Article IX of 1858 Treaty — No need to consider possible violation
of prohibition of threat or use of force — No need to consider whether conduct of

Nicaragua constitutes a military occupation.

*

Alleged violations of international environmental law.
Procedural obligations — Obligation to conduct environmental impact assess ‑
ment concerning activities that risk causing significant transboundary h▯arm

Content of environmental impact assessment depends on specific circumsta▯nces —
If assessment confirms risk of significant transboundary harm, State pla▯nning the
activity is required, in conformity with due diligence obligation, to no▯tify and
consult with potentially affected State, where necessary to determine ap▯propriate
measures to prevent or mitigate risk — Nicaragua’s dredging programme did not

give rise to risk of significant transboundary ha—m Nicaragua not required to
carry out transboundary environmental impact assessment — No obligation under
general international law to notify and consult since no risk of signifi▯cant trans
boundary harm — No conventional obligation to notify and consult in present
case — Court concludes that no procedural obligations breached by Nicaragu▯a.

Substantive obligations — Specific obligations concerning San Juan River in
1858 Treaty as interpreted by Cleveland Award — Customary law obligation to

exercise due diligence to avoid causing significant transboundary harm — No need
to discuss relationship between these obligations because no harm establ▯i—hed
No proof that dredging of Lower San Juan harmed Costa Rican wetland — Not
shown that dredging programme caused significant reduction in flow of Co▯lorado
River — Any diversion of water due to dredging did not seriously impair nav▯iga
tion on Colorado River or otherwise cause harm to Costaica — Court concludes

that no substantive obligations breached by Nicaragua.

*

7

5 Ord 1088.indb 11 19/10/16 12:01 669 certaines activitésf et construction d’unfe route (arrêt)

Respect des mesures conservatoires — Nicaragua ayant, en creusant deux caños
et en établissant une présence militaire dans le territoire litigieux en 2013, manqué
à ses obligations au titre de l’ordonnance du 8mars 2011 — Manquements aux
obligations prescrites par l’ordonnance du 22 novembre 2013 non établis.

*

Droits de navigation — Demande étant recevable — Article VI du traité de

1858 — Arrêt rendu par la Cour en l’affaire du Différend relatif à des droits de
navigation et des droits connexes — Nul besoin pour la Cour d’interpréter le
décret n o079‑2009 du Nicaragua — Cinq incidents ayant été invoqués par le
Costa Rica pour établir la violation de ses droits de navigati— Deux des cinq

incidents étant examinés — Cour concluant que le Nicaragua a violé les droits de
navigation que le Costa Rica tient du traité de 1858 — Nul besoin pour la Cour
d’examiner les autres incidents allégués.

*

Réparations — Cour ne pouvant faire droit aux demandes concernant l’abroga ‑
tion du décret n 079‑2009 et la cessation des activités de dragage — Constatation

des violations constituant une satisfaction appropriée au préjudic▯e immatériel
subi — Nul besoin de garanties de non ‑répétition — Costa Rica étant fondé à
recevoir indemnisation pour les dommages matériels — Parties devant mener des
négociations afin de s’entendre sur le montant de l’indemnité▯ — A défaut d’accord
dans un délai de douze mois, Cour devant déterminer, à la demande de l’une des

Parties, le montant de l’indemnité — Condamnation à supporter des frais de pro‑
cédure au titre de l’article du Statut n’étant pas appropriée.

* *

Questions en litige en l’affaire Nicaragua c. Costa Rica.
Obligations de nature procédurale.
Allégation de manquement à l’obligation d’une évaluation ▯de l’impact sur l’envi ‑
ronnement — Etat étant, au titre de l’obligation de faire preuve de la diligence

requise, tenu de vérifier si l’activité comporte un risque de d▯ommage transfrontière
important — Evaluation de l’impact sur l’environnement requise en présence d’un
tel risque — Absence de preuve que le Costa Rica a vérifié si une évaluation de
l’impact sur l’environnement était nécessaire avant de const▯ruire la route —

Ampleur du projet routier — Proximité du fleuve San Juan coulant en territoire
nicaraguayen — Risque d’érosion dû à la déforestation — Possibilité de catas‑
trophes naturelles dans la région Présence de deux zones humides d’importance
internationale dans la région — Construction de la route comportant un risque de
dommage transfrontière important — Absence d’urgence justifiant la construction

immédiate de la route — Cour n’ayant pas à se prononcer sur la question de l’exis
tence en droit international d’une dérogation, en cas d’urgence, à l’obligation d’ef ‑
fectuer une évaluation de l’impact sur l’environnement Costa Rica tenu à l’obli‑
gation de procéder à une évaluation de l’impact sur l’environnement Obligation
exigeant que le risque de dommage transfrontière important soit év▯alué ex ante —

Diagnostic de l’impact sur l’environnement et autres études eff▯ectuées par le Costa
Rica ayant consisté dans une évaluation post hoc — Costa Rica ne s’étant pas
acquitté de l’obligation d’effectuer une évaluation de l’▯impact sur l’environnement.

8

5 Ord 1088.indb 12 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 669

Compliance with provisional measures — Nicaragua breached its obligations
under Order of 8 March 2011 by excavating two caños and establishing a military
presence in disputed territory in 2013 — Breach of obligations under Court’s
Order of 22 November 2013 not established.

*

Rights of navigation — Claim is admissible — Article VI of the 1858 Treaty —
Court’s Judgment in Dispute regarding Navigational and Related Rights — No

need for the Court to interpret Nicaraguan Decree No. 079‑2009 — Five instances
of violations of navigational rights raised by Costa Rica — Two of the five
instances examined — Court concludes Nicaragua breached Costa Rica’s naviga ‑
tional rights pursuant to the 1858Treaty — Not necessary for Court to consider
the other incidents invoked by Costa Rica.

*

Reparation — Requests to order repeal of Decree No. 079‑2009 and cessation
of dredging activities cannot be granted— Declaration of breach provides ade ‑
quate satisfaction for non‑material injury suffered No need for guarantees of
non‑repetition — Costa Rica entitled to compensation for material damage —

Parties should engage in negotiation on amount of compensation — Failing agree‑
ment within 12 months, Court will determine amount at request of one of the Par ‑
ties— Award of costs under Article 64 of the Statute not appropriate.

* *

Issues in the Nicaragua v. Costa Rica case.

Procedural obligations.
Alleged breach of obligation to carry out environmental impact assessment—
Due diligence obligation requires State to ascertain whether a proposed activity
entails risk of significant transboundary harm — Environmental impact▯ assess ‑
ment required when risk is present — No evidence that Costa Rica determined
whether environmental impact assessment was necessary prior to construct▯ing the

road — Large scale of road project — Proximity to San Juan River on Nicara ‑
guan territory — Risk of erosion due to deforestation — Possibility of natural
disasters in area — Presence of two wetlands of international importance in
area — Construction of road carried a risk of significant transboundary ha▯r—
No emergency justifying immediate construction of road — Court need not decide

whether there is, in international law, an emergency exemption from obli▯gation to
carry out environmental impact assessment — Costa Rica under obligation to con
duct environmental impact assessment — Obligation requires ex ante evaluation of
risk of significant transboundary harm — Environmental Diagnostic Assessment
and other studies by Costa Rica were post hoc assessments — Costa Rica has not

complied with obligation to carry out environmental impact assessment.

8

5 Ord 1088.indb 13 19/10/16 12:01 670 certaines activitésf et construction d’unfe route (arrêt)

Allégation de violation de l’articl14 de la convention sur la diversité biolo‑
gique — Aucune violation n’ayant été établie.
Allégation de manquement à une obligation de notification et de co▯nsultation —
Question de l’obligation de notification et de consultation découlant du droit inter ‑
national général n’appelant pas d’examen puisque le Costa Rica n’a pas effectué

d’évaluation de l’impact sur l’environnement — Traité de 1858 ne faisant peser sur
le Costa Rica aucune obligation de notification envers le Nicaragua concernant la▯
construction de la route — Convention de Ramsar n’imposant aucune obligation de
nature procédurale.

*

Obligations de fond.
Allégation de manquement à l’obligation de faire preuve de la di▯ ligence requise en

vue de prévenir les dommages transfrontières importants — Sédiments attribuables
à la construction de la route représentant tout au plus, selon▯ odélisation et les
estimations réalisées par les experts, 2 % de la charge sédimentaire totale du fleuve
San Juan — Mesures effectivement produites devant la Cour n’indiquant pas que la▯
route ait eu un impact important sur les concentrations sédimentaires▯ du fleuve —
Augmentation des concentrations sédimentaires par suite de la constru▯ tion de la

route n’ayant pas en elle‑même causé un dommage transfrontièr ▯ e important —
Aucune atteinte importante à la morphologie du fleuve, à la navigat▯ ion ou au p‑o
gramme de dragage du Nicaragua n’ayant été établie — Absence de preuve d’une
atteinte importante à l’écosystème du fleuve ou à la quali▯ té de ses eaux — Moyens
liés aux autres dommages allégués ne pouvant être retenus.
Allégations de manquement à des obligations d’origine conventio▯nnelle — Aucun

manquement n’ayant été établi.
Demande concernant la violation de l’intégrité territoriale et ▯de la souvera‑
neté — Aucune violation n’ayant été établie.

*

Réparations — Constatation d’un fait illicite relativement à l’obligation d’▯effec ‑
tuer une évaluation de l’impact sur l’environnement constituant une mesure de
satisfaction appropriée — Nulle raison d’ordonner au Costa Rica de mettre fin à

des faits illicites en cours — Restitution et indemnisation ne constituant pas des
formes de réparation appropriées en l’absence de dommage import▯ant — Nul
besoin de procéder à la nomination d’un expert ou d’une comm▯ission pour évaluer
les dommages — Demande du Nicaragua tendant à ce qu’il soit ordonné au
Costa Rica de s’abstenir d’entreprendre tout nouveau projet sans avoir r▯éalisé une
évaluation de l’impact sur l’environnement étant rejetée.▯

ARRÊT

Présents: M. Abraham, président; M.Yusuf, vice‑président; MM.Owada, mes
Tomka, Bennouna, Cançado Trindade, Greenwood, M Xue,
Donoghue, M. Gaja, M me Sebutinde, MM. Bhandari, Robinson,
Gevorgian, juges; MM. Guillaume, Dugard, juges ad hoc ;
M. Couvreur, greffier.

9

5 Ord 1088.indb 14 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 670

Alleged breach of Article 14 of Convention on Biological Diversity — No viola‑
tion established.
Alleged breach of obligation to notify and consult — General international law
duty to notify and consult does not call for examination because Costa Rica has
not carried out environmental impact assessment — 1858 Treaty did not impose
obligation on Costa Rica to notify Nicaragua of construction of road — No proce‑
dural obligations arose under Ramsar Convention.

*

Substantive obligations.
Alleged breach of obligation to exercise due diligence to prevent causin▯g signifi ‑
cant transboundary harm — Modelling and estimates by experts suggest sediment
due to construction of road amounts to at most 2 per cent of San Juan River’s total
load — Actual measurements provided to Court do not indicate that road signifi ‑

cantly impacted sediment levels in river — Increase in sediment levels as a result of
construction of road did not in and of itself cause significant transbou▯ndary
harm — No significant harm to river’s morphology, to navigation or to N▯icara ‑
gua’s dredging programme established — No proof of significant harm to river’s
ecosystem or water quality — Arguments concerning other alleged harm fail.

Alleged breaches of treaty obligations— No violation established.

Claim concerning violation of territorial integrity and sovereignty No viola‑
tion established.

*

Reparation — Declaration of wrongful conduct in respect of obligation to

conduct environmental impact assessment is the appropriate measure of sa▯tis ‑
faction — No grounds to order Costa Rica to cease continuing wrongful acts —
Restitution and compensation not appropriate remedies in absence of sign▯ificant
harm — No need to appoint expert or committee to evaluate harm — Nicaragua’s
request to order Costa Rica not to undertake future development without an envi ‑
ronmental impact assessment dismissed.

JUDGMENT

Present: President Abraham ; Vice‑President Yusuf ; Judges Owada, Tomka,
Bennouna, Cançado Trindfade, Greenwood, Xue, Donofghue,
Gaja, Sebutinde, Bhandarfi, Robinson, Gevorgian ; Judges ad hoc
Guillaume, Dugard; Registrar Couvreur.

9

5 Ord 1088.indb 15 19/10/16 12:01 671 certaines activitésf et construction d’unfe route (arrêt)

En l’affaire relative à Certaines activités menées par le Nicaragua dans la
région frontalière et en l’affaire jointe (voir le paragraphe 19 ci-dessous) relative
à la Construction d’une route au Costa Rica le long du fleuve San Juan,

entre

la République du Costa Rica,

représentée par
S.Exc. M. Manuel A. González Sanz, ministre des affaires étrangères et des

cultes du Costa Rica;
S. Exc. M. Edgar Ugalde Alvarez, ambassadeur en mission spéciale,

comme agent;
S.Exc. M. Sergio Ugalde, ambassadeur du Costa Rica auprès du Royaume

des Pays-Bas, membre de la Cour permanente d’arbitrage,
comme coagent, conseil et avocat ;

M. Marcelo Kohen, professeur de droit international à l’Institut de hautes
études internationales et du développement de Genève, membre def l’Insti
tut de droit international,

M. Samuel Wordsworth, Q.C., membre des barreaux d’Angleterre et de Parisf,
Essex Court Chambers,
M. Arnoldo Brenes, conseiller principal auprès du ministère des affaires
étrangères et des cultes du Costa Rica, membre du barreau du Costaica,
M me Kate Parlett, solicitor (Queensland (Australie), Angleterre et pays de

melles),
M Katherine Del Mar, membre du barreau d’Angleterre, 4 New Square,
Lincoln’s Inn,

comme conseils et avocats ;
M. Simon Olleson, membre du barreau d’Angleterre, Old Square Chambers,

comme conseil;
M. Ricardo Otárola, conseiller auprès du ministère des affaires étrangères et

des cultes du Costa Rica,
M me Shara Duncan, conseillère auprès du ministère des affaires éftrangères et
des cultes du Costa Rica,
M. Gustavo Campos, ministre -conseiller et consul général du Costa Rica

auprès du Royaume des Pays-Bas,
M. Rafael Sáenz, ministre -conseiller à l’ambassade du Costa Rica au
Royaume des Pays -Bas,
M me Ana Patricia Villalobos, fonctionnaire du ministère des affaires éftran -
gères et des cultes du Costaica,

comme conseils adjoints ;
me
M Elisa Rivero, assistante administrative au ministère des affaires étran-
gères et des cultes du Costaica,

comme assistante,
et

la République du Nicaragua,

représentée par

10

5 Ord 1088.indb 16 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 671

In the case concerning Certain Activities Carried Out by Nicaragua in the Bor ‑
der Area, and in the joined case (see paragraph 19 below) concerning Construc‑
tion of a Road in Costa Rica along the San Juan River,

between

the Republic of Costa Rica,

represented by
H.E. Mr. Manuel A. González Sanz, Minister for Foreign Affairs and Wor -
ship of Costa Rica;

H.E. Mr. Edgar Ugalde Alvarez, Ambassador on Special Mission,

as Agent;
H.E. Mr. Sergio Ugalde, Ambassador of Costa Rica to the Kingdom of the
Netherlands, member of the Permanent Court of Arbitration,

as Co-Agent, Counsel and Advocate ;

Mr. Marcelo Kohen, Professor of International Law at the Graduate Insti -
tute of International and Development Studies, Geneva, member of the
Institut de droit international,
Mr. Samuel Wordsworth, Q.C., member of the English Bar, member of the
Paris Bar, Essex Court Chambers,

Mr. Arnoldo Brenes, Senior Adviser to the Ministry of Foreign Affairs and
Worship of Costa Rica, member of the Costa Rican Bar,
Ms Kate Parlett, Solicitor admitted in Queensland, Australia, and in Englanfd
and Wales,
Ms Katherine Del Mar, member of the English Bar, 4 New Square, Lincoln’sf

Inn,
as Counsel and Advocates ;

Mr. Simon Olleson, member of the English Bar, 13 Old Square Chambers,
as Counsel;

Mr. Ricardo Otárola, Adviser to the Ministry of Foreign Affairs and Wor -
ship of Costa Rica,
Ms Shara Duncan, Adviser to the Ministry of Foreign Affairs and Worship

of Costa Rica,
Mr. Gustavo Campos, Minister Counsellor and Consul General of CostaRica
to the Kingdom of the Netherlands,
Mr. Rafael Sáenz, Minister Counsellor at the Costa Rican Embassy in the
Kingdom of the Netherlands,

Ms Ana Patricia Villalobos, Official at the Ministry of Foreign Affairs anfd
Worship of Costa Rica,
as Assistant Counsel ;

Ms Elisa Rivero, Administrative Assistant at the Ministry of Foreign Affairfs
and Worship of Costa Rica,

as Assistant,

and

the Republic of Nicaragua,
represented by

10

5 Ord 1088.indb 17 19/10/16 12:01 672 certaines activitésf et construction d’unfe route (arrêt)

S. Exc. M. Carlos José Argüello Gómez, ambassadeur du Nicaragua auprès f
du Royaume des Pays-Bas,

comme agent et conseil ;
M. Stephen C. McCaffrey, professeur de droit international à la McGeorge
School of Law de l’Université du Pacifique à Sacramento, ancien membre

et ancien président de la Commission du droit international,
M. Alain Pellet, professeur à l’Université de Paris Ouest, Nanterrfe -
La Défense, ancien membre et ancien président de la Commission du
droitinternational, membre de l’Institut de droit international,

M. Paul S. Reichler, avocat au cabinet Foley Hoag LLP, membre des barreaux
de la Cour suprême des Etats-Unis d’Amérique et du district de Columbia,
M. Andrew B. Loewenstein, avocat au cabinet Foley Hoag LLP, membre du
barreau du Commonwealth du Massachusetts,

comme conseils et avocats ;
M. César Vega Masís, ministre adjoint des affaires étrangères, directeur des f

affaires juridiques, de la souveraineté et du territoire au ministèfre des
affaires étrangères du Nicaragua,
M. Walner Molina Pérez, conseiller juridique au ministère des affaires étran
gères du Nicaragua,

M. Julio César Saborio, conseiller juridique au ministère des affairefs étran -
gères du Nicaragua,
comme conseils;

M. Edgardo Sobenes Obregon, conseiller à l’ambassade du Nicaragua au f
Royaume des Pays-Bas,
M me Claudia Loza Obregon, premier secrétaire à l’ambassade du Nicarfagua

au Royaume des Pays-Bas,
M. Benjamin Samson, chercheur, Centre de droit international de Nanterre
(CEDIN), Université de Paris Ouest, Nanterre -La Défense,
M me Cicely O. Parseghian, avocate au cabinet Foley Hoag LLP, membre du

barreau du Commonwealth du Massachusetts,
M. Benjamin K. Guthrie, avocat au cabinet Foley Hoag LLP, membre du
barreau du Commonwealth du Massachusetts,
M. Ofilio J. Mayorga, avocat au cabinet Foley Hoag LLP, membre des bar -
reaux de la République du Nicaragua et de New York,

comme conseils adjoints;

M. Danny K. Hagans, spécialiste principal des sciences de la terre de Pacific
Watershed Associates, Inc.,
M. Robin Cleverly, consultant dans les domaines géographique et techniqufe,
M me Blanca P. Ríos Touma, Ph.D., professeur adjoint à l’Universidad

Tecnológica Indoamérica de Quito (Equateur),
M. Scott P. Walls, titulaire d’une maîtrise en architecture paysagère et enf
planification de l’environnement, propriétaire unique et géomorfphologue
fluvial de ScottWalls Consulting, spécialiste en écohydrologie de cbec
ecoengineering, Inc., et directeur financier et chef de projet pour Intefrna

meonal Watershed Partners,
M Victoria Leader, consultante dans les domaines géographique et technifque,
comme conseillers scientifiques et experts,

11

5 Ord 1088.indb 18 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 672

H.E. Mr. Carlos José Argüello Gómez, Ambassador of Nicaragua to the
Kingdom of the Netherlands,
as Agent and Counsel ;

Mr. Stephen C. McCaffrey, Professor of International Law at the University
of the Pacific, McGeorge School of Law, Sacramento, former member and
former Chair of the International Law Commission,

Mr. Alain Pellet, Professor at the University Paris Ouest, Nanterr-eLa Défense,
former member and former Chair of the International Law Commission,
member of the Institut de droit international,
Mr. Paul S. Reichler, Attorney-at-Law, Foley Hoag LLP, member of the

Bars of the United States Supreme Court and the District of Columbia,
Mr. Andrew B. Loewenstein, Attorney-at-Law, Foley Hoag LLP, member of
the Bar of the Commonwealth of Massachusetts,

as Counsel and Advocates ;
Mr. César Vega Masís, Deputy Minister for Foreign Affairs, Director off
Juridical Affairs, Sovereignty and Territory, Ministry of Foreign Affairs of

Nicaragua,
Mr. Walner Molina Pérez, Juridical Adviser, Ministry of Foreign Affairs off
Nicaragua,
Mr. Julio César Saborio, Juridical Adviser, Ministry of Foreign Affairs off
Nicaragua,

as Counsel;

Mr. Edgardo Sobenes Obregon, Counsellor, Embassy of Nicaragua in the
Kingdom of the Netherlands,
Ms Claudia Loza Obregon, First Secretary, Embassy of Nicaragua in the
Kingdom of the Netherlands,
Mr. Benjamin Samson, Researcher, Centre de droit international de Nanterre

(CEDIN), University of Paris Ouest, Nanterre -La Défense,
Ms Cicely O. Parseghian, Attorney-at-Law, Foley Hoag LLP, member of the
Bar of the Commonwealth of Massachusetts,
Mr. Benjamin K. Guthrie, Attorney -at-Law, Foley Hoag LLP, member of
the Bar of the Commonwealth of Massachusetts,

Mr. Ofilio J. Mayorga, Attorney-at-Law, Foley Hoag LLP, member of the
Bars of the Republic of Nicaragua and New York,
as Assistant Counsel ;

Mr. Danny K. Hagans, Principal Earth Scientist at Pacific Watershed Associ-
ates, Inc.,
Mr. Robin Cleverly, Geographical and Technical Consultant,

Ms Blanca P. Ríos Touma, Ph.D., Assistant Professor at Universidad Tec -
nológica Indoamérica in Quito, Ecuador,
Mr. Scott P. Walls, Master of Landscape Architecture — Environmental
Planning, Sole Proprietor and Fluvial Geomorphologist at Scott Walls
Consulting, Ecohydrologist at cbec ecoengineering, Inc., and Chief Finanf

cial Officer and Project Manager at International Watershed Partners,

Ms Victoria Leader, Geographical and Technical Consultant,

as Scientific Advisers and Experts,

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5 Ord 1088.indb 19 19/10/16 12:01 673 certaines activitésf et construction d’unfe route (arrêt)

La Cour,

ainsi composée,
après délibéré en chambre du conseil,

rend l’arrêt suivant :

1. Par requête déposée au Greffe de la Cour le 18 novembre 2010, la Répu-
blique du Costa Rica (ci-après le « Costa Rica») a introduit une instance contre

la République du Nicaragua (ci -après le « Nicaragua») en l’affaire relative à
Certaines activités menées par le Nicaragua dans la région fron▯talière (Costa Rica
c.Nicaragua) (ci-après dénommée l’« affaireCosta Rica c. Nicaragua»). Dans
cette requête, le Costa Rica fait en particulier grief au Nicaragua d’avoir envahi
et occupé un territoire costa -ricien, et d’y avoir construit un chenal ; il lui

reproche en outre d’exécuter un certain nombre de travaux (de drafgage du
fleuve San Juan, notamment) en violation de ses obligations internationales.
2. Dans sa requête, le Costa Rica invoque comme base de compétence de la
Cour l’article XXXI du traité américain de règlement pacifique adopté à fBogotá

le 30 avril 1948 (ci-après le «pacte de Bogotá »). Il entend également fonder la
compétence de la Cour sur la déclaration qu’il a faite le 20 février 1973 en vertu
du paragraphe 2 de l’article36 du Statut, ainsi que sur la déclaration que le
Nicaragua a faite le 24 septembre 1929 en vertu de l’article 36 du Statut de la
Cour permanente de Justice internationale (puis modifiée le 23 octobre 2001) et

qui, aux termes du paragraphe 5 de l’article 36 du Statut de la présente Cour, est
considérée, pour la durée lui restant à courir, comme comporftant acceptation de
la juridiction obligatoire de ladite Cour.
3. Le 18 novembre 2010, après avoir déposé sa requête, le Costa Rica a en

outre présenté une demande en indication de mesures conservatoiresf, en applica -
tion de l’article 41 du Statut de la Cour et des articles 73 à 75 de son Règlement.
4. Conformément au paragraphe 2 de l’article 40 du Statut, le greffier a
immédiatement communiqué au Gouvernement du Nicaragua une copie sifgnée

de la requête ;en application du paragraphe 3 du même article, tous les Etats
admis à ester devant la Cour ont été informés du dépôtf de la requête.
5. Sur les instructions données par la Cour en vertu de l’article 43 de son
Règlement, le greffier a adressé aux Etats parties à la convenftion relative aux
zones humides d’importance internationale, particulièrement comme fhabitats

des oiseaux d’eau, signée à Ramsar le 2 février 1971 (ci-après la «convention de
Ramsar »), la notification prévue au paragraphe 1 de l’article 63 du Statut.
6. La Cour ne comptant sur le siège aucun juge de la nationalité des fParties,
chacune d’elles s’est prévalue du droit que lui confère le pfaragraphe 3 de l’ar-

ticle31 du Statut de désigner un juge ad hoc pour siéger en l’affaire. Le
Costa Rica a désigné M. John Dugard et le Nicaragua, M. Gilbert Guillaume.
7. Par ordonnance du 8 mars 2011 (ci-après l’« ordonnance du 8 mars 2011 »),
la Cour, après avoir entendu les Parties, a indiqué certaines mesures conserva -

toires à l’intention de chacune d’entre elles. Elle a égalemfent ordonné à chaque
Partie de l’informer de la manière dont celle -ci assurerait la mise en œuvre des
mesures conservatoires indiquées. Par diverses communications, chacunfe des
Parties a porté à la connaissance de la Cour les mesures prises pafr elle en rap -
port avec l’ordonnance susmentionnée, tout en formulant des observfations sur

la manière dont l’autre Partie assurait l’exécution de laditfe ordonnance.
8. Par ordonnance du 5 avril 2011, la Cour a fixé au 5 décembre 2011 et au
6 août 2012, respectivement, les dates d’expiration des délais pour le défpôt d’un

12

5 Ord 1088.indb 20 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 673

The Court,

composed as above,
after deliberation,

delivers the following Judgment :

1. By an Application filed in the Registry of the Court on 18 November 2010,
the Republic of Costa Rica (hereinafter “Costa Rica”) instituted proceedings

against the Republic of Nicaragua (hereinafter “Nicaragua”) in tfhe case con -
cerning Certain Activities Carried Out by Nicaragua in the Border Area
(Costa Rica v. Nicaragua) (hereinafter referred to as the “Costa Rica v. Nicara‑
gua case”). In that Application, Costa Rica alleges in particular that Nicaragua
invaded and occupied Costa Rican territory, and that it dug a channel thereon ;

it further reproaches Nicaragua with conducting works (notably dredgingf of the
San Juan River) in violation of its international obligations.
2. In its Application, Costa Rica invokes as a basis of the jurisdiction of the
Court Article XXXI of the American Treaty on Pacific Settlement adopted at

Bogotá on 30 April 1948 (hereinafter the “Pact of Bogotá”). In addition,
Costa Rica seeks to found the jurisdiction of the Court on the declaration it
made on 20 February 1973 under Article 36, paragraph 2, of the Statute,
as well as on the declaration which Nicaragua made on 24 September 1929 (and
amended on 23 October 2001) under Article 36 of the Statute of the Permanent

Court of International Justice and which is deemed, pursuant to Article 36,
paragraph 5, of the Statute of the present Court, for the period which it still has
to run, to be acceptance of the compulsory jurisdiction of this Court.
3. On 18 November 2010, having filed its Application, Costa Rica also sub-

mitted a request for the indication of provisional measures, pursuant to Arti -
cle 41 of the Statute and Articles 73, 74 and 75 of the Rules of Court.
4. In accordance with Article 40, paragraph 2, of the Statute, the Registrar
communicated a signed copy of the Application forthwith to the Governmenft of

Nicaragua ; and, under paragraph 3 of that Article, all States entitled to appear
before the Court were notified of the filing of the Application.
5. Pursuant to the instructions of the Court under Article 43 of the Rules of
Court, the Registrar addressed to States parties to the Convention on Weftlands
of International Importance especially as Waterfowl Habitat, signed at Rfamsar

on 2 February 1971 (hereinafter the “Ramsar Convention”), the notification
provided for in Article 63, paragraph 1, of the Statute.
6. Since the Court included no judge of the nationality of the Parties uponf
the Bench, each of them, in exercise of the right conferred by Article 31, para -

graph 3, of the Statute, chose a judge ad hoc in the case. Costa Rica chose
Mr. John Dugard and Nicaragua chose Mr. Gilbert Guillaume.
7. By an Order of 8 March 2011 (hereinafter the “Order of 8 March 2011”),
the Court, having heard the Parties, indicated provisional measures addrfessed to

both Parties. The Court also directed each Party to inform it about compfliance
with the provisional measures. By various communications, the Parties eafch
notified the Court of the measures they had taken with reference to the fafore -
mentioned Order and made observations on the compliance by the other Parfty
with the said Order.

8. By an Order of 5 April 2011, the Court fixed 5 December 2011 and
6 August 2012 as the respective time -limits for the filing in the case of a Memo -

12

5 Ord 1088.indb 21 19/10/16 12:01 674 certaines activitésf et construction d’unfe route (arrêt)

mémoire par le Costa Rica et d’un contre-mémoire par le Nicaragua dans cette
affaire. Le mémoire et le contre -mémoire ont été déposés dans les délais ainsi
fixés.
9. Par requête déposée au Greffe le 22 décembre 2011, le Nicaragua a intro -

duit contre le Costa Rica une instance en l’affaire relative à la Construction d’une
route au Costa Rica le long du fleuve San Juan (Nicaragua c. Costa Rica)
(ci-après dénommée l’« affaire Nicaragua c. Costa Rica »). Dans cette requête, le
Nicaragua précise que l’affaire a trait à des «atteintes à [s]a souveraineté … et [à
des] dommages importants à l’environnement sur son territoire », soutenant en

particulier que le Costa Rica réalisait dans la zone de la frontière entre les deux
pays, le long du fleuve San Juan, de vastes travaux de construction routière, en
violation de plusieurs obligations internationales et avec de graves confséquences
pour l’environnement.
10. Dans sa requête, le Nicaragua invoque l’article XXXI du pacte de Bogotá

comme base de compétence de la Cour. Il entend également fonder laf compé -
tence de la Cour sur les déclarations d’acceptation susmentionnéfes (voir le para-
graphe 2 ci-dessus).
11. Conformément au paragraphe 2 de l’article 40 du Statut, le greffier a
immédiatement communiqué au Gouvernement du Costa Rica une copie signée

de la requête ;en application du paragraphe 3 du même article, tous les Etats
admis à ester devant la Cour ont été informés du dépôtf de la requête.
12. Sur les instructions données par la Cour en vertu de l’article 43 de son
Règlement, le greffier a adressé les notifications prévues au paragraphe 1 de l’ar -
ticle63 du Statut aux Etats parties à la convention de Ramsar, à la convention

de 1992 sur la diversité biologique et à la convention de 1992 confcernant la
conservation de la biodiversité et la protection des zones prioritairfes de faune et
de flore sauvages d’Amérique centrale.
13. La Cour ne comptant sur le siège aucun juge de la nationalité des fParties,

chacune d’elles s’est prévalue du droit que lui confère le pfaragraphe 3 de l’ar-
ticle31 du Statut de désigner un juge ad hoc pour siéger en l’affaire. Le Nicara -
gua a désigné M. Gilbert Guillaume et le Costa Rica, M. Bruno Simma.
14. Par ordonnance du 23 janvier 2012, la Cour a fixé au 19 décembre 2012
et au 19 décembre 2013, respectivement, les dates d’expiration des délais pour le
dépôt d’un mémoire par le Nicaragua et d’un contre-mémoire par le Costa Rica.

Le mémoire et le contre-mémoire ont été déposés dans les délais ainsi fixésf.
15. Dans le contre -mémoire qu’il a déposé le 6 août 2012 en l’affaire
Costa Rica c. Nicaragua, le Nicaragua a présenté quatre demandes reconven -
tionnelles. Dans sa première demande reconventionnelle, il priait la fCour de
déclarer que « la responsabilité du Costa Rica est engagée vis -à-vis du Nicara -

gua » en raison de « la perturbation et [de] l’arrêt éventuel de la navigation sur lfe
San Juan causés par la construction [de la] route ». Dans sa deuxième demande
reconventionnelle, il priait la Cour de déclarer qu’il « est devenu l’unique souve -
rain dans la zone jadis occupée par la baie de San Juan del Norte». Dans sa
troisième demande reconventionnelle, il priait la Cour de conclure quf’« [il] jouit

d’un droit de libre navigation sur le Colorado … tant que n’auront pas été réta -
blies les conditions de navigabilité qui existaient à l’époqfue de la conclusion du
traité de [limites de] 1858 ». Enfin, dans sa quatrième demande reconvention -
nelle, le Nicaragua faisait grief au Costa Rica d’avoir violé les mesures conser-
vatoires indiquées par la Cour dans son ordonnance du 8 mars 2011.

16. Lors d’une réunion que le président a tenue avec les représentants des
Parties le19 septembre 2012, celles-ci sont convenues de ne pas demander à la
Cour d’autoriser le dépôt d’une réplique et d’une duplfique dans l’affaire

13

5 Ord 1088.indb 22 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 674

rial by Costa Rica and a Counter -Memorial by Nicaragua. The Memorial and
the Counter-Memorial were filed within the time -limits thus prescribed.

9. By an Application filed in the Registry on 22 December 2011, Nicaragua

instituted proceedings against Costa Rica in the case concerning Construction of
a Road in Costa Rica along the San Juan River (Nicaragua v. Costa Rica) (here-
inafter referred to as the “Nicaragua v. Costa Rica case”). In that Application,
Nicaragua stated that the case related to “violations of Nicaraguan sfovereignty
and major environmental damages on its territory”, contending, in parfticular,

that Costa Rica was carrying out major road construction works in the border
area between the two countries along the San Juan River, in violation off several
international obligations and with grave environmental consequences.

10. In its Application, Nicaragua invokes Article XXXI of the Pact of Bogotá

as a basis for the jurisdiction of the Court. In addition, Nicaragua seefks to
found the jurisdiction of the Court on the aforementioned declarations afccept -
ing the jurisdiction of the Court (see paragraph 2 above).
11. In accordance with Article 40, paragraph 2, of the Statute, the Registrar
communicated a signed copy of the Application forthwith to the Governmenft of

Costa Rica ; and, under paragraph 3 of that Article, all States entitled to appear
before the Court were notified of the filing of the Application.
12. Pursuant to the instructions of the Court under Article 43 of its Rules,
the Registrar addressed the notifications provided for in Article 63, paragraph 1,
of the Statute, to States parties to the Ramsar Convention, to the 1992 fConven -

tion on Biological Diversity and to the 1992 Convention for the Conservation
of the Biodiversity and Protection of Priority Wilderness Areas in Central f
America.
13. Since the Court included no judge of the nationality of the Parties uponf

the Bench, each of them, in exercise of the right conferred by Article 31, para-
graph 3, of the Statute, chose a judge ad hoc in the case. Nicaragua chose
Mr. Gilbert Guillaume and Costa Rica chose Mr. Bruno Simma.
14. By an Order of 23 January 2012, the Court fixed 19 December 2012 and
19 December 2013 as the respective time -limits for the filing of a Memorial by
Nicaragua and a Counter -Memorial by Costa Rica. The Memorial and the

Counter-Memorial were filed within the time -limits thus prescribed.
15. In the Counter -Memorial it filed in the Costa Rica v. Nicaragua case on
6 August 2012, Nicaragua submitted four counter -claims. In its first counter -
claim, it requested the Court to declare that “Costa Rica bears responsibility to
Nicaragua” for “the impairment and possible destruction of navigatfion on the

San Juan River caused by the construction of [the] road”. In its secofnd
counter-claim, it asked the Court to declare that it “has become the sole
sovereign over the area formerly occupied by the Bay of San Juan del Norfte”.
In its third counter -claim, it requested the Court to find that “Nicaragua
has a right to free navigation on the Colorado . . . until the conditions of navig-

ability existing at the time the 1858 Treaty [of Limits] was concluded are
re-established”. Finally, in its fourth counter -claim, Nicaragua alleged that
Costa Rica violated the provisional measures indicated by the Court in its
Order of 8 March 2011.

16. At a meeting held by the President with the representatives of the Partifes
on 19 September 2012, the Parties agreed not to request the Court’s authorifza -
tion to file a Reply and a Rejoinder in the Costa Rica v. Nicaragua case. At the

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5 Ord 1088.indb 23 19/10/16 12:01 675 certaines activitésf et construction d’unfe route (arrêt)

Costa Rica c. Nicaragua. Lors de la même réunion, le coagent du Costa Rica a
élevé certaines objections à la recevabilité des trois premières demandes recon -
ventionnelles contenues dans le contre -mémoire du Nicaragua. Il a confirmé ces
objections dans une lettre datée du même jour.
Par lettres en date du 28 septembre 2012, le greffier a informé les Parties que

la Cour avait fixé au 30 novembre 2012 et au 30 janvier 2013, respectivement, les
dates d’expiration des délais pour le dépôt par le Costa Rica et le Nicaragua de
leurs observations écrites sur la recevabilité des trois premièfres demandes recon -
ventionnelles du Nicaragua. Les deux Parties ont présenté leurs obfservations

dans les délais ainsi fixés.
17. Dans des lettres datées du 19 décembre 2012, qui accompagnaient son
mémoire en l’affaire Nicaragua c. Costa Rica, le Nicaragua a prié la Cour d’exa -
miner «d’office [la question de savoir] si les circonstances de l’affairfe exige[aient]
l’indication de mesures conservatoires » et d’évaluer la nécessité de procéder à la

jonction des instances dans les affaires Nicaragua c. Costa Rica et Costa Rica
c. Nicaragua.
Par lettre datée du 15 janvier 2013, le greffier a, sur les instructions du pré -
sident, demandé au Costa Rica de faire part à la Cour, le 18 février 2013 au plus
tard, de ses vues sur ces deux questions. Le Costa Rica a exposé ses vues dans le

délai ainsi fixé.
18. Par lettres en date du 11 mars 2013, le greffier a informé les Parties que la
Cour considérait que les circonstances de l’affaire Nicaragua c. Costa Rica, telles
qu’elles se présentaient alors à elle, n’étaient pas de nfature à exiger l’exercice
de son pouvoir d’indiquer d’office des mesures conservatoires en vertu de l’ar -

ticle75 du Règlement.
19. Par deux ordonnances distinctes datées du 17 avril 2013, la Cour a joint
les instances dans les affaires Costa Rica c. Nicaragua et Nicaragua c. Costa Rica.
20. Par une communication datée du même jour, M. Simma, qui avait été
désigné par le Costa Rica pour siéger en qualité de juge ad hoc en l’affaire Nica ‑

ragua c. Costa Rica, a fait part à la Cour de sa décision de démissionner de ses
fonctions, comme suite à la jonction d’instances susmentionnée. Depuis lors,
MM. Guillaume et Dugard siègent en qualité de juges ad hoc dans les affaires
jointes (voir les paragraphes 6 et 13 ci-dessus).

21. Par ordonnance du 18 avril 2013,la Cour s’est prononcée sur la recevabi -
lité des demandes reconventionnelles du Nicaragua en l’affaire Costa Rica
c.Nicaragua . Elle a conclu qu’il n’y avait pas lieu pour elle de statuer sur la
recevabilité de la première demande reconventionnelle du Nicaraguaf comme
telle. Elle a déclaré que les deuxième et troisième demandesf reconventionnelles

étaient irrecevables comme telles. La Cour a également déclaré qu’il n’y avait
pas lieu pour elle de connaître de la quatrième demande reconventifonnelle
comme telle et que les Parties pourraient aborder, dans la suite de la pfrocédure,
toute question relative à la mise en œuvre des mesures conservatoifres indiquées
par elle dans son ordonnance du 8 mars 2011.

22. Le 23 mai 2013, le Costa Rica, se référant à l’article 41 du Statut et
à l’article76 du Règlement, a déposé au Greffe une demande tendant à la
modification de l’ordonnance en indication de mesures conservatoires frendue le
8 mars 2011. Dans ses observations écrites y afférentes, datées du 14 juin 2013,
le Nicaragua priait la Cour de rejeter la demande du Costa Rica tout

en l’invitant,à son tour, à modifier à d’autres égards l’ordonnance fdu 8 mars
2011 sur le fondement de l’article 76 de son Règlement. Le Costa Rica a pré -
senté à la Cour ses observations écrites sur la demande du Nicafragua le
20 juin 2013.

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5 Ord 1088.indb 24 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 675

same meeting, the Co -Agent of Costa Rica raised certain objections to the
admissibility of the first three counter-claims contained in the Counter-emorial
of Nicaragua. He confirmed these objections in a letter of the same day.f

By letters dated 28 September 2012, the Registrar informed the Parties that

the Court had fixed 30 November 2012 and 30 January 2013 as the respective
time-limits for the filing of written observations by Costa Rica and Nicaragua
on the admissibility of the latter’s first three counter -claims. Both Parties filed
their observations within the time-limits thus prescribed.

17. By letters dated 19 December 2012, which accompanied its Memorial in
the Nicaragua v. Costa Rica case, Nicaragua requested the Court to “decide
proprio motu whether the circumstances of the case require[d] the indication of
provisional measures” and to consider whether there was a need to joifn the

proceedings in the Nicaragua v. Costa Rica and Costa Rica v. Nicaragua cases.

By a letter dated 15January 2013, the Registrar, acting on the instructions of
the President, asked Costa Rica to inform the Court, by 18 February 2013 at the
latest, of its views on both questions. Costa Rica communicated its views within

the time-limit thus prescribed.
18. By letters dated 11 March 2013, the Registrar informed the Parties that
the Court was of the view that the circumstances of the Nicaragua v. Costa Rica
case, as they presented themselves to it at that time, were not such as fto require
the exercise of its power under Article 75 of the Rules of Court to indicate pro -

visional measures proprio motu.
19. By two separate Orders dated 17 April 2013, the Court joined the pro -
ceedings in the Costa Rica v. Nicaragua and Nicaragua v. Costa Rica cases.
20. By a communication of the same date, Mr. Simma, who had been chosen

by Costa Rica to sit as judge ad hoc in the Nicaragua v. Costa Rica case,
informed the Court of his decision to resign from his functions, followifng
the above-mentioned joinder of proceedings. Thereafter, Judges Guillaume
and Dugard sat as judges ad hoc in the joined cases (see paragraphs 6 and 13
above).

21. By an Order of 18 April 2013, the Court ruled on the admissibility of
Nicaragua’s counter-claims in the Costa Rica v. Nicaragua case. It concluded
that there was no need for it to adjudicate on the admissibility of Nicafragua’s
first counter-claim as such. It found the second and third counter -claims inad -
missible as such. The Court also found that there was no need for it to fentertain

the fourth counter -claim as such, and that the Parties might take up any ques -
tion relating to the implementation of the provisional measures indicatefd by the
Court in its Order of 8 March 2011 in the further course of the proceedings.

22. On 23 May 2013, Costa Rica, with reference to Article 41 of the Statute
and Article 76 of the Rules of Court, filed with the Registry a request for the
modification of the Order indicating provisional measures made on 8 March
2011. In its written observations thereon, dated 14 June 2013, Nicaragua asked
the Court to reject Costa Rica’s request, while in its turn requesting the Court

to otherwise modify the Order of 8 March 2011 on the basis of Article 76 of the
Rules of Court. Costa Rica communicated to the Court its written observations
on Nicaragua’s request on 20 June 2013.

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5 Ord 1088.indb 25 19/10/16 12:01 676 certaines activitésf et construction d’unfe route (arrêt)

23. Par ordonnance du 16 juillet 2013, la Cour a déclaré que « les circons-
tances, telles qu’elles se présent[aient alors] à elle, n[’éftaient] pas de nature à
exiger l’exercice de son pouvoir de modifier les mesures indiquées dans l’ordon -
nance du 8 mars 2011». Elle a néanmoins réaffirmé lesdites mesures.

24. Le 24 septembre 2013, le Costa Rica, se référant à l’article 41 du Statut et
aux articles 73 à 75 du Règlement, a déposé au Greffe une demande en indica -
tion de nouvelles mesures conservatoires en l’affaire Costa Rica c. Nicaragua.

25. Le 11 octobre 2013, le Nicaragua a déposé au Greffe une demande en

indication de mesures conservatoires en l’affaire Nicaragua c. Costa Rica. Il a
proposé que sa demande soit examinée concurremment avec la demandef en ind-i
cation de nouvelles mesures conservatoires présentée par le Costa Rica dans l’af-
faire Costa Rica c. Nicaragua, au cours d’une même série d’audiences. Par lettre
du 14 octobre 2013, le Costa Rica a exprimé son opposition à cette proposition

du Nicaragua. Par lettres datées du même jour, le greffier a infofrmé les Parties
que la Cour avait décidé d’examiner les deux demandes séparéfment.
26. Par ordonnance du 22 novembre 2013 en l’affaire CostaRica c. Nicaragua,
la Cour, après avoir entendu les Parties, a réaffirmé les mesufres conservatoires
indiquées dans son ordonnance du 8 mars 2011 et en a indiqué de nouvelles à

l’intention des deux Parties. Elle a également ordonné à chafque Partie de l’infor -
mer, tous les trois mois, de la manière dont celle -ci assurerait la mise en œuvre
des mesures conservatoires indiquées. Par diverses communications, chfacune des
deux Parties a porté à la connaissance de la Cour les mesures prises par elle en
rapport avec l’ordonnance susmentionnée, tout en formulant des obsfervations

sur la manière dont l’autre Partie assurait l’exécution de lfadite ordonnance.
27. Par ordonnance du 13 décembre 2013 en l’affaire Nicaragua c. Costa Rica,
la Cour, après avoir entendu les Parties, a déclaré « que les circonstances, telles
qu’elles se présent[aient alors] à [elle], n[’étaient] pafs de nature à exiger l’exercice

de son pouvoir d’indiquer des mesures conservatoires en vertu de l’farticle 41 du
Statut».
28. Lors d’une réunion que le président a tenue avec les représentants des
Parties le 22 janvier 2014, le Nicaragua a demandé à la Cour d’autoriser un
second tour de procédure écrite dans l’affaire Nicaragua c. Costa Rica, demande
à laquelle le Costa Rica a fait objection. Par ordonnance du 3 février 2014, la

Cour a autorisé le dépôt d’une réplique par le Nicaragua fet d’une duplique par
le Costa Rica, et fixé au 4 août 2014 et au 2 février 2015, respectivement, les
dates d’expiration des délais dans lesquels ces pièces devaient être déposées. La
réplique du Nicaragua et la duplique du Costa Rica ont été dûment déposées
dans les délais ainsi fixés.

29. Par lettres en date du 2 avril 2014, le greffier a informé les Parties que la
Cour, agissant en vertu du paragraphe 1 de l’article 54 de son Règlement, avait
fixé au 3 mars 2015 la date d’ouverture de la procédure orale dans les affaires
jointes.
30. Dans une lettre datée du 4 août 2014, qui accompagnait sa réplique en l’af -

faire Nicaragua c. Costa Rica, le Nicaragua a proposé que la Cour désigne « un
expert neutre, sur la base des articles 66 et 67 du Règlement ». Par lettre du
14 août 2014, le CostaRica a indiqué que, selon lui, «rien ne justifi[ait] que la Cour
exerce son pouvoir de désigner un expert, comme le demand[ait] le Nicfaragua ».
31. Par une lettre en date du 15 octobre 2014, le Nicaragua a sollicité le

report au mois de mai 2015 de la date d’ouverture de la procédure orale dans les
affaires jointes. Faisant valoir que, dans la lettre du 14août 2014 mentionnée au
paragraphe précédent, le Costa Rica avait indiqué que sa duplique en l’affaire

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5 Ord 1088.indb 26 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 676

23. By an Order of 16 July 2013, the Court found that “the circumstances, as
they now present themselves to the Court, are not such as to require thef exercise
of its power to modify the measures indicated in the Order of 8 March 2011”.
The Court however reaffirmed the said provisional measures.

24. On 24 September 2013, Costa Rica, with reference to Article 41 of the
Statute and Articles 73, 74 and 75 of the Rules of Court, filed with the Registry
a request for the indication of new provisional measures in the Costa Rica v.
Nicaragua case.
25. On 11 October 2013, Nicaragua filed with the Registry a request for the

indication of provisional measures in the Nicaragua v. Costa Rica case. Nicara -
gua suggested that its request be heard concurrently with Costa Rica’s request
for the indication of new provisional measures in the Costa Rica v. Nicaragua
case, at a single set of oral proceedings. By letter of 14 October 2013, Costa Rica
objected to Nicaragua’s suggestion. By letters dated 14 October 2013, the

Registrar informed the Parties that the Court had decided that it would fconsider
the two requests separately.
26. By an Order of 22 November 2013 rendered in the Costa Rica v. Nicara ‑
gua case, the Court, having heard the Parties, reaffirmed the provisional f
measures indicated in its Order of 8 March 2011 and indicated new provisional

measures addressed to both Parties. The Court also directed each Party tfo inform
it, at three-month intervals, as to compliance with the provisional measures. By
various communications, each of the Parties notified the Court of the mefasures
they had taken with reference to the aforementioned Order and made observa -
tions on the compliance by the other Party with the said Order.

27. By an Order of 13December 2013 rendered in the Nicaraguav. Costa Rica
case, the Court, after hearing the Parties, found “that the circumstafnces, as they
now present themselves to the Court, are not such as to require the exerfcise of

its power under Article 41 of the Statute to indicate provisional measures”.

28. At a meeting held by the President with the representatives of the Partifes
on 22 January 2014, Nicaragua requested the Court to authorize a second round f
of written pleadings in the Nicaragua v. Costa Rica case, while Costa Rica
objected. By an Order of 3 February 2014, the Court authorized the submission

of a Reply by Nicaragua and a Rejoinder by Costa Rica, and fixed 4 August
2014 and 2 February 2015 as the respective time -limits for the filing of those
pleadings. The Reply of Nicaragua and the Rejoinder of Costa Rica were duly
filed within the time-limits so prescribed.

29. By letters dated 2 April 2014, the Registrar informed the Parties that the
Court, in accordance with Article 54, paragraph 1, of the Rules of Court, had
fixed 3 March 2015 as the date for the opening of the oral proceedings in the
joined cases.
30. In a letter dated 4August 2014, which accompanied its Reply in the Nica ‑

ragua v. Costa Rica case, Nicaragua suggested that the Court appoint “a neutral
expert on the basis of Articles 66 and 67 of the Rules”. By letter of 14 August
2014, Costa Rica indicated that it was of the view “that there [was] no basis forf
the Court to exercise its power to appoint an expert as requested by Nicaragua”.
31. By a letter dated 15 October 2014, Nicaragua requested that the opening

of the oral proceedings in the joined cases be postponed until May 2015.f On the
basis that Costa Rica had stated, in its letter of 14 August 2014 referred to in the
previous paragraph, that the evidence submitted by the Parties “w[oulfd] be sup -

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5 Ord 1088.indb 27 19/10/16 12:01 677 certaines activitésf et construction d’unfe route (arrêt)

Nicaragua c. Costa Rica « viendra[it] préciser et compléter » les éléments de
preuve communiqués par les Parties, le Nicaragua a déclaré qu’fil n’était selon lui
«ni approprié ni équitable de lui laisser moins d’un mois pour afnalyser les nou-
veaux éléments scientifiques et rapports d’experts que le Costaf Rica soumet-

tra[it]…, et pour préparer sa réponse ». Par lettre du 20 octobre 2014, le Costa
Rica s’est opposé à cette demande, soutenant en particulier quef tout report des
audiences et du règlement de l’affaire Costa Rica c. Nicaragua lui porterait pré-
judice, que le Nicaragua disposait de suffisamment de temps pour analyser la
duplique et préparer sa réponse avant l’ouverture des audiencesf, et que la

demande du Nicaragua était tardive. Par lettres en date du 17 novembre 2014,
le greffier a informé les Parties que la Cour avait décidé de freporter la date d’ou -
verture de la procédure orale dans les affaires jointes au 14 avril 2015.
32. Par lettres en date du 5décembre2014, le greffier, se référant aux commun-i
cations mentionnées au paragraphe 30 ci-dessus, a informé les Parties que la Cour

estimait utile que, au cours des audiences dans les deux affaires, cellefs-ci fassent
entendre les experts dont elles avaient annexé les rapports à leurs écritures, en pa-r
ticulier MM. Thorne et Kondolf. Le greffier a également indiqué que la Cour sau -
rait gré aux Parties de bien vouloir lui soumettre, le 15 janvier 2015 au plus tard,
leurs propositions quant aux modalités d’audition desdits experts.f Le Nicaragua a

présenté ses propositions dans le délai ainsi fixé. Par lettfre datée dujanvier2015,
le Costa Rica a formulé certaines observations sur les propositions du Nicaragfua.
33. Dans une lettre datée du 2 février 2015, qui accompagnait sa duplique en
l’affaire Nicaragua c. Costa Rica, le Costa Rica a évoqué la possibilité d’une
visite sur les lieux à « l’emplacement de la route ». Par lettre datée du

10 février 2015, le Nicaragua s’est déclaré disposé à fournir toute fl’assistance
possible aux fins de l’organisation de « pareille visite à l’emplacement de la route
et du fleuve San Juan de Nicaragua ». Il a également réitéré sa proposition ten -
dant à ce que la Cour désigne un expert (voir le paragraphe 30 ci-dessus) afin

d’évaluer la construction de la route, et a proposé que ledit efxpert fasse partie de
la délégation de la Cour qui se rendrait sur les lieux. Par lettref datée du
11 février 2015, le Costa Rica, en réaction à la lettre du Nicaragua du
10 février 2015, a notamment déclaré que la désignation d’un expert parf la Cour
n’était pas nécessaire. Par lettres datées du 25 février 2015, le greffier a informé

les Parties que la Cour avait décidé de ne pas effectuer de visitef sur les lieux.
34. Par lettres du greffier en date du 4 février 2015, il a été indiqué aux Parties
qu’elles devaient, le 2 mars 2015 au plus tard, indiquer à la Cour le nom des
experts qu’elles désiraient faire entendre et communiquer les autrfes renseigne -
ments requis par l’article 57 du Règlement. Il leur a également été demandé de
soumettre à la Cour, le 16mars 2015 au plus tard, les exposés écrits de ces experts,

dont elles ont été informées qu’ils tiendraient lieu d’interrogatoirfe principal (ces
exposés devant se limiter à un résumé des rapports déjàf soumis par l’expert
concerné ou à des observations sur d’autres rapports d’experft versés au dossier de
l’affaire). Les Parties ont encore été invitées à s’efntendre, le 16mars 2015 au plus
tard, sur la durée du contre-interrogatoire et de l’interrogatoire complémentaire.

Par ces mêmes lettres, le greffier a aussi fait connaître aux Parfties les détails
suivants quant au déroulement de la procédure d’audition des exfperts. Après
avoir fait la déclaration solennelle prévue à l’article 64 du Règlement, chaque
expert serait invité par la Partie le présentant à confirmer sofn exposé écrit. L’autre
Partie aurait alors la possibilité de le soumettre à un contre -interrogatoire sur la

teneur dudit exposé ou de ses rapports antérieurs. L’interrogatfoire complémen -
taire serait ensuite limité aux questions soulevées lors du contref -interrogatoire.
Enfin, les juges auraient la possibilité de poser des questions à fl’expert.

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5 Ord 1088.indb 28 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 677

plemented and completed” in Costa Rica’s Rejoinder in the Nicaragua v.
Costa Rica case, Nicaragua expressed the view that it would be “inadequate and f
inequitable for [it] to have less than one month to analyze and respond to
Costa Rica’s new scientific information and expert reports”. By letter off 20Octo -

ber 2014, Costa Rica opposed this request, arguing in particular that any delay
in the Court hearing and adjudging the Costa Rica v. Nicaragua case would
prejudice Costa Rica, that Nicaragua had sufficient time to analyse the Rejoin -
der and formulate its response before the commencement of the hearings, f
and that Nicaragua’s request was belated. By letters dated 17 November 2014,

the Registrar informed the Parties that the Court had decided to postponfe
the date for the opening of the oral proceedings in the joined cases until 1f4April
2015.
32. By letters dated 5December 2014, referring to the communications men -
tioned in paragraph 30 above, the Registrar informed the Parties that the Court

would find it useful if, during the course of the hearings in the two cafses, they could
call the experts whose reports were annexed to the written pleadings, in particular
Mr. Thorne and Mr. Kondolf. The Registrar also indicated that the Court would
be grateful if, by 15January 2015 at the latest, the Parties would make suggestions
regarding the modalities of the examination of those experts. Such suggefstions

were received from Nicaragua within the time -limit indicated. By a letter dated
20 January 2015, CostaRica commented on the suggestions of Nicaragua.
33. In a letter dated 2February 2015, which accompanied its Rejoinder in the
Nicaragua v. Costa Rica case, Costa Rica raised the possibility of a site visit to
the “location of the Road”. By a letter dated 10 February 2015, Nicaragua

expressed its willingness to assist to the fullest possible extent in thfe organiza
tion “of such a visit at the location of the road and the San Juan def Nicaragua
River”. It also reiterated its proposal that the Court appoint an expfert (see par-
graph 30 above) to assess the construction of the road, and suggested that thfe

expert be included in the Court’s delegation for any site visit. By af letter dated
11 February 2015, Costa Rica commented on Nicaragua’s letter of 10 February
2015, stating in particular that the appointment of an expert by the Court was
unnecessary. By letters dated 25 February 2015, the Registrar informed the Par -
ties that the Court had decided not to carry out a site visit.

34. By letters of the Registrar dated 4 February 2015, the Parties were
informed that they should indicate to the Court, by 2 March 2015 at the latest,
the names of the experts they intended to call, and communicate the othefr infor -
mation required by Article 57 of the Rules of Court. The Parties were also
instructed to provide the Court, by 16 March 2015 at the latest, with written

statements of these experts (limited to a summary of the expert’s owfn reports or
to observations on other expert reports in the case file), and were infformed that
these would replace the examination -in-chief. In addition, the Court invited the
Parties to come to an agreement as to the allocation of time for the crofss-exam -
ination and re -examination of experts by 16 March 2015 at the latest.

By the same letters, the Registrar also notified the Parties of the follfowing
details regarding the procedure for examining the experts. After having made
the solemn declaration required under Article 64 of the Rules of Court, the
expert would be asked by the Party calling him to endorse his written stfatement.
The other Party would then have an opportunity for cross -examination on the

contents of the expert’s written statement or his earlier reports. Ref-examination
would thereafter be limited to subjects raised in cross -examination. Finally, the
judges would have an opportunity to put questions to the expert.

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5 Ord 1088.indb 29 19/10/16 12:01 678 certaines activitésf et construction d’unfe route (arrêt)

35. Par lettres datées du 2 mars 2015, les Parties ont indiqué le nom des
experts qu’elles désiraient faire entendre lors des audiences, et ffourni les autres
renseignements les concernant, requis par l’article 57 du Règlement (voir le
paragraphe 34 ci-dessus).

36. Sous le couvert d’une lettre en date du 3 mars 2015, le Costa Rica a fait
parvenir à la Cour un enregistrement vidéo qu’il souhaitait voir versé au dossier
de l’affaire et présenté à l’audience. Par lettre du 13 mars 2015, le Nicaragua a
dit n’avoir aucune objection à la demande du Costa Rica et a formulé certaines
observations concernant l’utilité dudit enregistrement ; il a également indiqué

qu’il produirait des photographies en réponse. Le greffier a informé les Parties,
par lettres datées du 23 mars 2015, que la Cour avait décidé d’accéder à la
demande du Costa Rica.
37. Par lettres datées du 16 mars 2015, les Parties ont communiqué les exposés
écrits des experts qu’elles désiraient faire entendre lors des faudiences. Le Costiaca

a par ailleurs prié la Cour de bien vouloir proroger jusqu’au 20mars 2015 le délai
dans lequel elles pourraient transmettre leur éventuel accord ou leurfs positions res
pectives quant au temps qu’il conviendrait de consacrer au contre -interrogatoire et
à l’interrogatoire complémentaire desdits experts, demande àf laquelle la Cour a fait
droit. Les Parties n’étant toutefois pas parvenues à s’entenfdre en tous points à cet

égard dans le délai ainsi prorogé, le greffier les a informéfes, par lettres
du 23 mars 2015, de la décision de la Cour quant au temps maximal qui pourrait
être alloué aux auditions. Les Parties ont été invitées àf préciser, dans ce cadre,
l’ordre dans lequel elles souhaitaient présenter leurs experts, aifnsi que la durée
exacte qu’elles envisageaient de consacrer au contre -interrogatoire de chaque

expert appelé par l’autre Partie, ce qu’elles ont fait par lettfres en date des mars
et 2 avril2015. Le greffier a fait tenir aux Parties, par lettres datées d0vfril2015,
le calendrier détaillé de l’audition des experts, tel qu’arrfêté par la Cour.
38. Par lettres du 23 mars 2015, le greffier a informé les Parties que, s’agissant

de l’affaire Nicaragua c. Costa Rica, la Cour souhaitait que chacune d’entre elles
produise, le 10 avril 2015 au plus tard, une carte représentant le fleuve San Juan
ainsi que la route construite par le Costa Rica et indiquant avec précision les
lieux dont il était question dans les principales études mentionnéfes dans les
exposés écrits remis à la Cour le 16 mars 2015 (voir le paragraphe 37 ci-dessus).
Sous le couvert de lettres en date du 10 avril 2015, le Nicaragua et le Costa Rica

ont chacun transmis à la Cour des versions imprimées et électroniques des cartes
établies par leurs soins.
39. Par une lettre datée du 23 mars 2015, le Nicaragua a, comme il l’avait
annoncé (voir le paragraphe 36 ci-dessus), fait tenir à la Cour des photographies
qu’il souhaitait verser au dossier de l’affaire. Par une lettre enf date du

31 mars 2015, le Costa Rica a fait savoir à la Cour qu’il n’avait pas d’objection
à la demande du Nicaragua. Le greffier a informé les Parties, parf lettres datées
du 8 avril 2015, que la Cour avait décidé d’accéder à la demande du fNicaragua.
40. Par une lettre en date du 13 avril 2015, le Costa Rica a sollicité le dépôt,
par le Nicaragua, d’un exemplaire du rapport de la mission consultatifve Ramsar
o
n 72 portant sur la réserve nicaraguayenne Refugio de Vida Silvestre Río
San Juan (réserve naturelle du fleuve San Juan). Par une lettre datée du
16 avril 2015, le Nicaragua a indiqué n’être en possession que d’un pfrojet de
rapport, en langue espagnole, qu’il a joint à son courrier. Ultéfrieurement, sous
le couvert d’une lettre datée du 24 avril 2015, le Nicaragua a transmis à la Cour

les observations qu’il avait formulées le 30 novembre 2011 (en version originale
espagnole, certains passages étant traduits en anglais) sur le projeft de rapport de
la mission consultative Ramsar, ainsi que la réponse fournie par le Sfecrétariat

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5 Ord 1088.indb 30 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 678

35. By letters dated 2 March 2015, the Parties indicated the names of the
experts they wished to call at the hearings, and provided the other infofrmation
concerning them required by Article 57 of the Rules of Court (see paragraph 34
above).

36. Under cover of a letter dated 3 March 2015, Costa Rica communicated
to the Court a video which it wished to be included in the case file andf presented
at the hearings. By a letter dated 13 March 2015, Nicaragua stated that it had
no objection to Costa Rica’s request and presented certain comments on the
utility of the video ; it also announced that it would produce photographs in

response. By letters dated 23 March 2015, the Registrar informed the Parties
that the Court had decided to grant Costa Rica’s request.

37. By letters dated 16 March 2015, the Parties communicated the written
statements of the experts they intended to call at the hearings. Costa Rica also

asked the Court to extend to 20 March 2015 the time-limit within which the Par-
ties might transmit an agreement or their respective positions regardingf the allo-
cation of time for the cross -examination and re -examination of those experts,
which was granted by the Court. However, since the Parties were unable to
agree fully on this matter within the time -limit thus extended, the Registrar

informed them, by letters of 23 March 2015, of the Court’s decision in respect of
the maximum time that could be allocated for the examinations. In this connec -
tion, the Parties were invited to indicate the order in which they wished to pres -
ent their experts, and the precise amount of time they wished to reservef for the
cross-examination of each of the experts called by the other Party, which theyf

did by letters dated 30 March and 2 April 2015. By letters dated 10 April 2015,
the Registrar communicated to the Parties the detailed schedule for the exam -
ination of the experts, as adopted by the Court.
38. By letters of 23 March 2015, the Registrar informed the Parties that, in

relation to the Nicaragua v. Costa Rica case, the Court wished each of them to
produce, by 10 April 2015 at the latest, a map showing the San Juan River and
the road constructed by Costa Rica, and indicating the precise locations dis -
cussed in the key studies referred to in the written statements providedf to the
Court on 16 March 2015 (see paragraph 37 above). Under cover of letters dated
10 April 2015, Nicaragua and Costa Rica each provided the Court with printed

and electronic versions of the maps they had prepared.

39. By a letter dated 23 March 2015, Nicaragua, as announced (see para-
graph 36 above), communicated to the Court photographs that it wished to be
included in the case file. By a letter dated 31 March 2015, Costa Rica informed

the Court that it had no objection to Nicaragua’s request. By letters dated
8 April 2015, the Registrar informed the Parties that the Court had decided to
grant Nicaragua’s request.
40. By a letter dated 13 April 2015, Costa Rica requested that Nicaragua file
a copy of the report of Ramsar Advisory Mission No. 72 in relation to Nicara -

gua’s Refugio de Vida Silvestre Río San Juan (San Juan River Wildlife Refuge).
By a letter dated 16 April 2015, Nicaragua indicated that it was in possession
only of a draft report, in Spanish, which it enclosed with its letter. Sfubsequently,
under cover of a letter dated 24 April 2015, Nicaragua transmitted to the Court
the comments it had submitted on 30 November 2011 on the draft report of the

Ramsar Advisory Mission (original Spanish version and English translatifon of
certain extracts), as well as the reply from the Ramsar Secretariat datfed
19 December 2011 (original Spanish version only). The Parties later provided

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5 Ord 1088.indb 31 19/10/16 12:01 679 certaines activitésf et construction d’unfe route (arrêt)

de la convention le 19 décembre 2011 (en version originale espagnole unique -
ment). Les Parties ont par la suite communiqué à la Cour des tradfuctions
anglaises des documents déposés en espagnol par le Nicaragua.
41. Par une lettre en date du 21vril 2015, le greffier a informé les Parties que

la Cour attendait du Nicaragua qu’il produise, en vertu de l’articfle62 du Règle
ment, le texte intégral de deux documents dont des extraits avaient éfté repro-
duits en annexe à son contre -mémoire en l’affaire Costa Rica c. Nicaragua. Par
une lettre en date du 24 avril 2015, le Nicaragua a communiqué à la Cour le
texte intégral de la version originale espagnole des documents demandés. Une

traduction anglaise certifiée exacte en a été transmise par le Nicaragua sous le
couvert d’une lettre en date du 15 mai 2015.
42. Par lettre du 2avril2015, le CostaRica a demandé que des photographies
soient versées au dossier de l’affairNicaragua c. Costa Rica . Le Nicaragua a
déclaré, dans une lettre en date du 29 avril 2015, qu’il s’opposait à cette requête,

considérée trop tardive. Par lettres datées du 29ril 2015le greffier a fait savoir
aux Parties que la Cour avait décidé de ne pas accéder à la fdemande du Cstica.

*

43. Conformément au paragraphe 2 de l’article 53 de son Règlement, la
Cour, après avoir consulté les Parties, a décidé que des exefmplaires des pièces de
procédure et des documents annexés seraient rendus accessibles au fpublic à l’ou-

verture de la procédure orale. er
44. Des audiences publiques ont été tenues du 14 avril 2015 au 1 mai 2015
dans les instances jointes. Ces audiences ont porté, du 14 au 17 ainsi que du 28
au 29 avril 2015, sur l’affaire Costa Rica c. Nicaragua et, du 20 au 24 avril ainsi
que du 30 avril au 1 ermai 2015, sur l’affaire Nicaragua c. Costa Rica. Ont été

entendus en leurs plaidoiries et réponses :
En l’affaireCosta Rica c. Nicaragua,

Pour le Costa Rica : S.Exc. M. Edgar Ugalde Alvarez,

S.Exc. M. Sergio Ugalde,
M. Arnoldo Brenes,
M. Samuel Wordsworth,
M. Marcelo Kohen,
M me Kate Parlett,
me
M Katherine Del Mar.
Pour le Nicaragua : S. Exc. M. Carlos José Argüello Gómez,
M. Alain Pellet,

M. Paul S. Reichler,
M. Andrew B. Loewenstein,
M. Stephen C. McCaffrey.

En l’affaire Nicaragua c. Costa Rica,
Pour le Nicaragua : S. Exc. M. Carlos José Argüello Gómez,

M. Paul S. Reichler,
M. Andrew B. Loewenstein,
M. Stephen C. McCaffrey,
M. Alain Pellet.

Pour le Costa Rica : S.Exc. M. Edgar Ugalde Alvarez,
M. Arnoldo Brenes,

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5 Ord 1088.indb 32 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 679

the Court with English translations of the documents submitted in Spanish by
Nicaragua.

41. By a letter dated 21 April 2015, the Registrar informed the Parties that

the Court had decided to request, under Article 62 of its Rules, that Nicaragua
produce the full text of two documents, excerpts of which were annexed tfo its
Counter-Memorial in the Costa Rica v. Nicaragua case. By a letter dated
24 April 2015, Nicaragua communicated to the Court the full text of the original
Spanish versions of the documents requested. Certified English translatifons were

transmitted by Nicaragua under cover of a letter dated 15 May 2015.

42. By letter of 28 April 2015, Costa Rica asked for photographs to be
included in the Nicaragua v. Costa Rica case file. In a letter dated 29 April 2015,
Nicaragua stated that it objected to this request, which it considered hfad been

made too late. By letters dated 29 April 2015, the Registrar informed the Parties
that the Court had decided not to grant Costa Rica’s request.

*

43. In accordance with Article 53, paragraph 2, of the Rules of Court, after
ascertaining the views of the Parties, the Court decided that copies of fthe plead-
ings and documents annexed would be made accessible to the public at the

opening of the oral proceedings.
44. Public hearings were held in the joined cases from 14ril 2015 to 1 May
2015. Between 14 and 17 April 2015 and 28 and 29 April 2015, the hearings
focused on the Costa Rica v. Nicaragua case, and between 20 and 24 April 2015
and 30 April and 1 May 2015 on the Nicaragua v. Costa Rica case. The Court

heard the oral arguments and replies of :
In the Costa Rica v. Nicaragua case,

For Costa Rica: H.E. Mr. Edgar Ugalde Alvarez,

H.E. Mr. Sergio Ugalde,
Mr. Arnoldo Brenes,
Mr. Samuel Wordsworth,
Mr. Marcelo Kohen,
Ms Kate Parlett,

Ms Katherine Del Mar.
For Nicaragua: H.E. Mr. Carlos José Argüello Gómez,
Mr. Alain Pellet,

Mr. Paul S. Reichler,
Mr. Andrew B. Loewenstein,
Mr. Stephen C. McCaffrey.

In the Nicaragua v. Costa Rica case,
For Nicaragua: H.E. Mr. Carlos José Argüello Gómez,

Mr. Paul S. Reichler,
Mr. Andrew B. Loewenstein,
Mr. Stephen C. McCaffrey,
Mr. Alain Pellet.

For Costa Rica: H.E. Mr. Edgar Ugalde Alvarez,
Mr. Arnoldo Brenes,

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5 Ord 1088.indb 33 19/10/16 12:01 680 certaines activitésf et construction d’unfe route (arrêt)

me
M Katherine Del Mar,
M. Marcelo Kohen,
M. Samuel Wordsworth,
M me Kate Parlett,

S. Exc. M. Sergio Ugalde.

45. Dans l’affaire Costa Rica c. Nicaragua, le Costa Rica a fait entendre
comme expert, à l’audience publique du 14 avril 2015 (après-midi), M. Thorne.
Par la suite, à l’audience publique du 17 avril 2015 (matin), le Nicaragua a fait

entendre les experts suivants:MM. van Rhee et Kondolf. En l’affaire Nicaragua
c. Costa Rica, le Nicaragua a fait entendre, lors des audiences publiques du
20 avril 2015 (matin et après-midi), les experts ci-aprèsMM. Weaver, Kondolf,
Andrews et Sheate. Le Costa Rica a quant à lui fait entendre comme experts, à
l’audience publique du 24 avril 2015 (matin), MM. Cowx et Thorne. Plusieurs

juges ont posé des questions aux experts, qui y ont répondu oralemfent.
46. Au cours des audiences, des membres de la Cour ont également posé faux
Parties des questions auxquelles celles-ci ont répondu oralement, conformément
au paragraphe 4 de l’article 61 du Règlement.

* *

47. Dans sa requête en l’affaire Costa Rica c. Nicaragua, le Costa Rica a for-

mulé les demandes suivantes :
«Pour ces motifs, tout en se réservant le droit de compléter, préfciser ou

modifier la présente requête, le Costa Rica prie la Cour de dire et juger que
le Nicaragua viole ses obligations internationales mentionnées au para -
graphe 1 de la présente requête, à raison de son incursion en territoifre
costa-ricien et de l’occupation d’une partie de celui -ci, des graves dom -
mages causés à ses forêts pluviales et zones humides protégéfes, des

dommages qu’il entend causer au Colorado, à ses zones humides et àf ses
écosystèmes protégés, ainsi que des activités de dragage fet de creusement
d’un canal qu’il mène actuellement dans le San Juan.
En particulier, le Costa Rica prie la Cour de dire et juger que, par son

comportement, le Nicaragua a violé :
a) le territoire de la République du Costa Rica, tel qu’il a été convenu et

délimité par le traité de limites de 1858, la sentence Cleveland ainsi que
les première et deuxième sentences Alexander ;
b) les principes fondamentaux de l’intégrité territoriale et de l’finterdiction
de l’emploi de la force consacrés par la Charte des Nations Unies et la

Charte de l’Organisation des Etats américains ;
c) l’obligation faite au Nicaragua par l’article IX du traité de limites
de 1858 de ne pas utiliser le SanJuan pour perpétrer des actes d’hostilité;
d) l’obligation de ne pas causer de dommages au territoire costa -ricien;
e) l’obligation de ne pas dévier artificiellement le San Juan de son cours

naturel sans le consentement du Costa Rica;
f) l’obligation de ne pas interdire la navigation de ressortissants costfa -
riciens sur le SanJuan ;
g) l’obligation de ne pas mener d’opérations de dragage dans le Safn Juan
si ces activités ont un effet dommageable pour le territoire costa -ricien

(y compris le Colorado), conformément à la sentence Cleveland de1888 ;

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5 Ord 1088.indb 34 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 680

Ms Katherine Del Mar,
Mr. Marcelo Kohen,
Mr. Samuel Wordsworth,
Ms Kate Parlett,

H.E. Mr. Sergio Ugalde.

45. In the Costa Rica v. Nicaragua case, Costa Rica called Mr. Thorne as an
expert during the public hearing of 14 April 2015 (afternoon). Later, during the
public hearing of 17 April 2015 (morning), Nicaragua called the following

experts : Mr. van Rhee and Mr. Kondolf. In the Nicaragua v. Costa Rica case,
Nicaragua called the following experts during the public hearings of
20 April 2015 (morning and afternoon): Mr. Weaver, Mr. Kondolf, Mr.Andrews
and Mr. Sheate. Costa Rica called Mr. Cowx and Mr. Thorne as experts during
the public hearing of 24 April 2015 (morning). A number of judges put ques -

tions to the experts, to which replies were given orally.
46. At the hearings, Members of the Court also put questions to the Parties,f
to which replies were given orally, in accordance with Article 61, paragraph 4,
of the Rules of Court.

* *

47. In its Application filed in the Costa Rica v. Nicaragua case, Costa Rica

made the following claims :
“For these reasons, and reserving the right to supplement, amplify orf

amend the present Application, Costa Rica requests the Court to adjudge
and declare that Nicaragua is in breach of its international obligations as
referred to in paragraph 1 of this Application as regards the incursion into
and occupation of Costa Rican territory, the serious damage inflicted to its
protected rainforests and wetlands, and the damage intended to the Colo -

rado River, wetlands and protected ecosystems, as well as the dredging afnd
canalization activities being carried out by Nicaragua on the San Juan
River.
In particular the Court is requested to adjudge and declare that, by its

conduct, Nicaragua has breached :
(a) the territory of the Republic of Costa Rica, as agreed and delimited by

the 1858Treaty of Limits, the Cleveland Award and the first and second
Alexander Awards;
(b) the fundamental principles of territorial integrity and the prohibition f
of use of force under the Charter of the United Nations and the

Charter of the Organization of American States ;
(c) the obligation imposed upon Nicaragua by Article IX of the 1858 Treaty
of Limits not to use the San Juan River to carry out hostile acts ;
(d) the obligation not to damage Costa Rican territory ;
(e) the obligation not to artificially channel the San Juan River away from f

its natural watercourse without the consent of Costa Rica ;
(f) the obligation not to prohibit the navigation on the San Juan River by
Costa Rican nationals;
(g) the obligation not to dredge the San Juan River if this causes damage
to Costa Rican territory (including the Colorado River), in accordance

with the 1888 Cleveland Award ;

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5 Ord 1088.indb 35 19/10/16 12:01 681 certaines activitésf et construction d’unfe route (arrêt)

h) les obligations découlant de la convention de Ramsar sur les zones
humides;
i) l’obligation de ne pas aggraver ou étendre le différend, que cef soit par
des actes visant le Costa Rica, et consistant notamment à étendre

laportion de territoire costa-ricien envahie et occupée, ou par l’adoption
de toute autre mesure ou la conduite d’activités qui porteraient
atteinte à l’intégrité territoriale du Costa Rica en violation du droit
international.»

Le Costa Rica a également prié la Cour de « déterminer les réparations dues

par le Nicaragua à raison, en particulier, de toute mesure du type def celles …
mentionnées» ci-dessus.
48. Au cours de la procédure écrite en l’affaire Costa Rica c. Nicaragua, les
conclusions ci-après ont été présentées par les Parties :

Au nom du Gouvernement du Costa Rica,

dans le mémoire :

« Pour ces motifs, tout en se réservant le droit de compléter, préfciser ou
modifier les présentes conclusions :

1. Le Costa Rica prie la Cour de dire et juger que, par son comporte -
ment, le Nicaragua a violé :

a) l’obligation de respecter la souveraineté et l’intégrité fterritoriale de la

République du Costa Rica selon les frontières définies par le traité de
limites de 1858 et précisées par la commission de démarcation établie efn
vertu de la convention Pacheco-Matus, et en particulier par les première
et deuxième sentences Alexander ;
b) l’interdiction de l’emploi de la force consacrée par la Charte fdes

Nations Unies au paragraphe 4 de son article 2 et par la Charte de l’Or -
ganisation des Etats américains en son article premier et ses articles 19,
21 et 29;
c) l’obligation qui lui est faite par l’article IX du traité de limites
de 1858 de ne pas utiliser le fleuve San Juan pour perpétrer des actes

d’hostilité;
d) les droits de libre navigation dont les ressortissants costaiciens peuvent
se prévaloir sur le San Juan conformément au traité de limites de 1858,
à la sentence Cleveland et à l’arrêt de la Cour du 13 juillet 2009 ;
e) l’obligation de ne pas mener sur le fleuve San Juan d’opérations de

dragage, de déviation ou de modification de son cours ni d’autres ftra -
vaux qui causeraient des dommages au territoire costa -ricien (y compris
le fleuve Colorado), à son environnement, ou aux droits du Costa Rica
découlant de la sentence Cleveland;
f) l’obligation de consulter le Costa Rica sur l’exécution des obligations

découlant de la convention de Ramsar, en particulier de celle que
leparagraphe 1 de l’article 5 de cette convention fait aux deux Etats
de coordonner leurs politiques et réglementations futures relatives àf
la conservation des zones humides, de leur flore et de leur faune ;

et
g) l’ordonnance en indication de mesures conservatoires rendue par la
Cour le 8 mars 2011 ;

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5 Ord 1088.indb 36 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 681

(h) the obligations under the Ramsar Convention on Wetlands ;

(i) the obligation not to aggravate and extend the dispute by adopting
measures against Costa Rica, including the expansion of the invaded

and occupied CostaRican territory or by adopting any further measure
or carrying out any further actions that would infringe Costa Rica’s
territorial integrity under international law.”

Costa Rica also requested the Court to “determine the reparation which must

be made by Nicaragua, in particular in relation to any measures of the kfind
referred to . . . above”.
48. In the course of the written proceedings in the Costa Rica v. Nicaragua
case, the following submissions were presented by the Parties :

On behalf of the Government of Costa Rica,

in the Memorial :

“For these reasons, and reserving the right to supplement, amplify orf
amend the present submissions :

1. Costa Rica requests the Court to adjudge and declare that, by its
conduct, Nicaragua has breached :

(a) the obligation to respect the sovereignty and territorial integrity of tfhe

Republic of Costa Rica, within the boundaries delimited by the
1858 Treaty of Limits and further defined by the Demarcation Com -
mission established by the Pacheco -Matus Convention, in particular by
the first and second Alexander Awards ;
(b) the prohibition of use of force under Article 2 (4) of the United Nations

Charter and Articles1, 19, 21 and 29 of the Charter of the Organization
of American States ;

(c) the obligation of Nicaragua under Article IX of the 1858 Treaty of
Limits not to use the San Juan to carry out hostile acts ;

(d) the rights of Costa Rican nationals to free navigation on the San Juan
in accordance with the 1858Treaty of Limits, the Cleveland Award and
the Court’s Judgment of 13 July 2009;
(e) the obligation not to dredge, divert or alter the course of the San Juanf,

or conduct any other works on the San Juan, if this causes damage to
Costa Rican territory (including the Colorado River), its environment,
or to Costa Rican rights in accordance with the Cleveland Award ;

(f) the obligation to consult with Costa Rica about implementing obliga-

tions arising from the Ramsar Convention, in particular the obligation
to co-ordinate future policies and regulations concerning the conserva-
tion of wetlands and their flora and fauna under Article 5 (1) of the
Ramsar Convention; and

(g) the Court’s Order for Provisional Measures of 8 March 2011;

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5 Ord 1088.indb 37 19/10/16 12:01 682 certaines activitésf et construction d’unfe route (arrêt)

la Cour est également priée de dire et juger que le Nicaragua :
h) est tenu de mettre un terme à ces violations et d’apporter répafration
pour les dommages ainsi causés.

2. Par voie de conséquence, la Cour est priée d’ordonner au Nicarafgua:

a) de procéder à un retrait total, notamment de tous les membres de sfes
forces et autres agents (qu’il s’agisse de civils, de membres des forces de

police ou de sécurité, ou de volontaires) du territoire costa -ricien
dénommé Isla Portillos, situé sur la rive droite du San Juan, et d’empê -
cher leur retour sur ce territoire;
b) de cesser toute activité de dragage du San Juan dans la zone située entre
le point où celui -ci donne naissance au Colorado et l’embouchure du

San Juan dans la mer des Caraïbes (ci -après la « zone»), en attendant :
i) qu’une évaluation adéquate de l’impact sur l’environnemenft ait été

réalisée;
ii) que tout projet de dragage dans la zone ait été notifié au CostfaRica,
dans un délai d’au moins troismois avant la mise en œuvre de celu-ici ;
iii) que les observations susceptibles d’être formulées par le Costaf Rica
dans le mois suivant la notification aient été dûment prises enf

considération;

c) de n’entreprendre dans la zone aucune opération de dragage ou autrfe
susceptible de causer des dommages importants au territoire costa -
ricien (y compris au fleuve Colorado) ou à son environnement, ou de
porter atteinte aux droits du Costa Rica, conformément à la sentence
Cleveland.

3. La Cour est enfin priée de déterminer, lors d’une phase ultéfrieure, les

mesures de réparation et de satisfaction dues par le Nicaragua. »
Au nom du Gouvernement du Nicaragua,

dans le contre -mémoire:
«Pour les motifs exposés ci -dessus, la République du Nicaragua prie la

Cour:
1) de rejeterles demandes et conclusions présentées par le Costa Rica dans
ses écritures;

2) de dire et juger que:
i) le Nicaragua jouit de la pleine souveraineté sur le caño reliant la

lagune de Harbor Head au fleuve San Juan proprement dit, dont la
rive droite constitue la frontière terrestre établie par le traitéf de
limites de 1858, tel qu’interprété par les sentences Cleveland
et Alexander ;
ii) le Costa Rica est tenu de respecter la souveraineté et l’intégrité

territoriale du Nicaragua, en observant les frontières délimitées
par le traité de 1858, tel qu’interprété par les sentences Clevefland et
Alexander;
iii) le Nicaragua a le droit, conformément au traité de 1858 tel qu’inter -
prété par les sentences arbitrales ultérieures, d’effectuer fles travaux

qu’il estime opportuns pour améliorer la navigabilité du fleufve
San Juan, y compris des travaux de dragage ;

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5 Ord 1088.indb 38 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 682

and further to adjudge and declare that Nicaragua is :
(h) obliged to cease such breaches and to make reparation therefore.

2. The Court is requested to order, in consequence, that Nicaragua :

(a) withdraw any presence, including all troops and other personnel
(whether civilian, police or security, or volunteers) from that part off

Costa Rica known as Isla Portillos, on the right bank of the San Juan,
and prevent any return there of any such persons ;

(b) cease all dredging activities on the San Juan in the area between the
point of bifurcation of the Colorado River and the San Juan and the

outlet of the San Juan in the Caribbean Sea (‘the area’), pendinfg:
(i) an adequate environmental impact assessment ;

(ii) notification to CostaRica of further dredging plans for the area, not
less than three months prior to the implementation of such plans;
(iii) due consideration of any comments of Costa Rica made within one
month of notification ;

(c) not engage in any dredging operations or other works in the area if and f
to the extent that these may cause significant harm to Costa Rican
territory (including the Colorado River) or its environment, or to
impair Costa Rica’s rights under the Cleveland Award.

3. The Court is also requested to determine, in a separate phase, the

reparation and satisfaction to be made by Nicaragua.”
On behalf of the Government of Nicaragua,

in the Counter-Memorial :
“For the reasons given herein, the Republic of Nicaragua requests thef

Court to:
(1) dismiss and reject the requests and submissions of Costa Rica in her
pleadings;

(2) adjudge and declare that:
(i) Nicaragua enjoys full sovereignty over the caño joining Harbor

Head Lagoon with the San Juan River proper, the right bank of
which constitutes the land boundary as established by the
1858 Treaty as interpreted by the Cleveland and Alexander
Awards ;
(ii) Costa Rica is under an obligation to respect the sovereignty and

territorial integrity of Nicaragua, within the boundaries delimited
by the 1858 Treaty of Limits as interpreted by the Cleveland and
Alexander Awards;
(iii) Nicaragua is entitled, in accordance with the 1858 Treaty as inter -
preted by the subsequent arbitral awards, to execute works to

improve navigation on the San Juan River as it deems suitable,
and that these works include the dredging of the San Juan de Nic-
aragua River ; and,

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5 Ord 1088.indb 39 19/10/16 12:01 683 certaines activitésf et construction d’unfe route (arrêt)

iv) ce faisant, le Nicaragua a le droit, s’il l’estime opportun, de réftablir
la situation qui existait à l’époque de la conclusion du traitéf d1e858;
v) les seuls droits dont le Costa Rica peut se prévaloir sur le
fleuve San Juan de Nicaragua sont ceux définis par ledit traité, tel

qu’interprété par les sentences Cleveland et Alexander. »
49. Lors de la procédure orale dans les instances jointes, les conclusionfs

ci-après ont été présentées par les Parties en l’affaire fCosta Rica c. Nicaragua:
Au nom du Gouvernement du Costa Rica,

à l’audience du 28 avril 2015 :

« Pour les motifs exposés dans ses écritures et plaidoiries, la Réfpublique
du Costa Rica prie la Cour :

1) de rejeter toutes les demandes du Nicaragua ;
2) de dire et juger :

a) que le « territoire litigieux », tel que défini par la Cour dans ses ordon -
nances des 8 mars 2011 et 22 novembre 2013, relève de la souveraineté

de la République du Costa Rica;
b) que, en occupant et en revendiquant une partie du territoire costa -ricien,
le Nicaragua a violé :

i) l’obligation de respecter la souveraineté et l’intégrité fterritoriale de
la République du Costa Rica selon les frontières définies par le traité
de limites de 1858 et précisées par la commission de démarcation

établie en vertu de la convention Pacheco -Matus, et en particulier
par les première et deuxième sentences Alexander ;
ii) l’interdiction de la menace ou de l’emploi de la force consacréfe par
la Charte des Nations Unies au paragraphe 4 de son article 2 et par
la Charte de l’Organisation des Etats américains en son article 22;

iii) l’interdiction de soumettre le territoire d’autres Etats, fût -ce de
manière temporaire, à une occupation militaire, en contravention de
l’article 21 de la Charte de l’Organisation des Etats américains ; et
iv) l’obligation qui lui est faite par l’articleIX du traité de limites de1858

de ne pas utiliser le fleuve SanJuan pour perpétrer des actes d’hostilit;
c) que, par ailleurs, le Nicaragua a violé :

i) l’obligation de respecter le territoire et l’environnement du
Costa Rica, y compris la « Humedal Caribe Noreste », une zone

humide d’importance internationale protégée au titre de la convfen -
tion de Ramsar qui se trouve en territoire costa -ricien;
ii) les droits perpétuels de libre navigation dont le Costa Rica peut se
prévaloir sur le SanJuan conformément au traité de limites de1858, à
la sentenceCleveland de 1888 et à l’arrêt de la Cour du 13juillet2009 ;

iii) l’obligation qui lui est faite par la sentence Cleveland de 1888 et le
droit conventionnel et coutumier applicable d’informer et de consul -
ter le Costa Rica au sujet de toute opération de dragage, de déviation
ou de modification du cours du fleuve San Juan ou de tous autres
travaux sur le fleuve qui seraient susceptibles de causer des dom -

mages au territoire costa -ricien (y compris au fleuve Colorado), à
son environnement, ou aux droits du Costa Rica;
iv) l’obligation de réaliser une évaluation appropriée de l’ifmpact trans-

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5 Ord 1088.indb 40 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 683

(iv) in so doing, Nicaragua is entitled as it deems suitable to -establish
the situation that existed at the time the 18Treaty was concluded;
(v) the only rights enjoyed by Costa Rica on the San Juan de Nicara-
gua River are those defined by said Treaty as interpreted by the

Cleveland and Alexander Awards.”
49. At the oral proceedings in the joined cases, the following submissions

were presented by the Parties in the Costa Rica v. Nicaragua case:
On behalf of the Government of Costa Rica,

at the hearing of 28 April 2015:

“For the reasons set out in the written and oral pleadings, the Repubflic
of Costa Rica requests the Court to :

(1) reject all Nicaraguan claims ;
(2) adjudge and declare that :

(a) sovereignty over the ‘disputed territory’, as defined by the Courtf in its
Orders of 8 March 2011 and 22 November 2013, belongs to the Repub -

lic of Costa Rica;
(b) by occupying and claiming Costa Rican territory, Nicaragua has
breached:

(i) theobligation to respect the sovereignty and territorial integrity of
the Republic of CostaRica, within the boundaries delimited by the
1858 Treaty of Limits and further defined by the Demarcation

Commission established by the Pacheco -Matus Convention, in
particular by the first and second Alexander Awards ;
(ii) theprohibition of the threat or use of force under Article 2 (4)of
the Charter of the United Nations and Article 22 of the Charter
of the Organization of American States ;

(iii) the prohibition to make the territory of other States the object,
even temporarily, of military occupation, contrary to Article 21 of
the Charter of the Organization of American States ; and
(iv) the obligation of Nicaragua under ArticleIX of the 1858 Treaty of

Limits not to use the San Juan River to carry out hostile acts ;
(c) by its further conduct, Nicaragua has breached :

(i) the obligation to respect Costa Rica’s territory and environment,
including its wetland of international importance under the

Ramsar Convention ‘Humedal Caribe Noreste’, on Costa Rican
territory;
(ii) Costa Rica’s perpetual rights of free navigation on the San Juan
in accordance with the 1858 Treaty of Limits, the 1888 Cleveland
Award and the Court’s Judgment of 13 July 2009 ;

(iii) the obligation to inform and consult with Costa Rica about
any dredging, diversion or alteration of the course of the San Juan
River, or any other works on the San Juan River that may
cause damage to Costa Rican territory (including the Colorado
River), its environment, or Costa Rican rights, in accordance

with the 1888 Cleveland Award and relevant treaty and customary
law;
(iv) the obligation to carry out an appropriate transboundary environ -

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frontière sur l’environnement tenant compte de tout risque de dom-
mage important en territoire costa -ricien;
v) l’obligation de ne pas mener d’opérations de dragage, de dévfiation
ou de modification du cours du San Juan, ni d’autres travaux sur le

fleuve San Juan qui causeraient un dommage au territoire costa -
ricien (y compris le fleuve Colorado), à son environnement, ou aux
droits du Costa Rica découlant de la sentence Cleveland de 1888 ;
vi) les obligations découlant des ordonnances en indication de mesures
conservatoires rendues par la Cour les 8 mars 2011 et 22 novembre

2013;
vii) l’obligation de consulter le CostaRica sur l’exécution des obligations
découlant de la convention de Ramsar, en particulier de celle que le
paragraphe 1 de l’article 5 de cette convention fait aux deux Etats de
coordonner leurs politiques et réglementations futures relatives àf la

conservation des zones humides, de leur flore et de leur faune ; et
viii) l’accord conclu entre les Parties par l’échange de notes en date des
19 et 22 septembre 2014 tendant à permettre au Costa Rica de navi -
guer sur le fleuve San Juan pour procéder à la fermeture du caño
oriental construit par le Nicaragua en 2013;

d) que le Nicaragua ne peut entreprendre aucune opération de dragage ou f

autre susceptible de causer des dommages au territoire du Costa Rica
(y compris au fleuve Colorado) ou à son environnement, ou de porter
atteinte aux droits du Costa Rica découlant de la sentence Cleveland de
1888, dont celui de ne pas voir son territoire occupé sans son consenfte -
ment exprès;

3) d’ordonner en conséquence au Nicaragua :

a) d’abroger, par les moyens de son choix, les dispositions du décretf
no 079-2009 et du règlement y annexé en date du 1 er octobre 2009 qui

sont contraires au droit de libre navigation reconnu au Costa Rica par
l’article VI du traité de limites de 1858, la sentence Cleveland de 1888
et l’arrêt de la Cour du 13 juillet 2009 ;
b) de cesser toute activité de dragage du San Juan dans la zone de
Delta Costa Rica et dans le cours inférieur de ce fleuve, en attendant :

i) qu’une évaluation appropriée de l’impact transfrontière sur l’envi -
ronnement tenant compte de tout risque de dommage important en

territoire costa-ricien ait été réalisée par le Nicaragua et transmise
au Costa Rica;
ii) que tout projet de dragage dans la zone de Delta Costa Rica et dans
le San Juan inférieur ait été formellement notifié par écrit au f
Costa Rica, dans un délai d’au moins trois mois avant la mise en

œuvre de celui-ci; et
iii) que les observations formulées par le Costa Rica lorsqu’il aura reçu
cette notification aient été dûment prises en considération ;

c) d’apporter réparation, par voie d’indemnisation, à raison defs dommages
matériels causés au Costa Rica, à savoir, mais non exclusivement :

i) les dommages découlant de la construction des caños artificiels et
de la destruction des arbres et de la végétation sur le « territoire
litigieux»;

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5 Ord 1088.indb 42 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 684

mental impact assessment, which takes account of all potential
significant adverse impacts on Costa Rican territory;
(v) the obligation not to dredge, divert or alter the course of the San
Juan River, or conduct any other works on the San Juan River, if

this causes damage to Costa Rican territory (including the Colo -
rado River), its environment, or to Costa Rican rights under the
1888 Cleveland Award;
(vi) the obligations arising from the Orders of the Court indicat -
ing provisional measures of 8 March 2011 and 22 November

2013 ;
(vii) the obligation to consult with Costa Rica on the implementation
of obligations arising from the Ramsar Convention, in particular
the obligation to co -ordinate future policies and regulations con -
cerning the conservation of wetlands and their flora and fauna

under Article 5 (1) of the Ramsar Convention ; and
(viii) the agreement between the Parties, established in the exchange of
notes dated 19 and 22 September 2014, concerning navigation on
the San Juan River by Costa Rica to close the eastern caño con -
structed by Nicaragua in 2013 ;

(d) Nicaragua may not engage in any dredging operations or other works

if and to the extent that these may cause damage to Costa Rican terri -
tory (including the Colorado River) or its environment, or which
may impair Costa Rica’s rights under the 1888 Cleveland Award,
including its right not to have its territory occupied without its express
consent;

(3) to order, in consequence, that Nicaragua must :

(a) repeal, by means of its own choosing, those provisions of the Decree
No. 079-2009 and the Regulatory Norms annexed thereto of 1 October

2009 which are contrary to Costa Rica’s right of free navigation under
Article VI of the 1858Treaty of Limits, the 1888Cleveland Award, and
the Court’s Judgment of 13 July 2009 ;
(b) cease all dredging activities on the San Juan River in the vicinity of
Delta Costa Rica and in the lower San Juan River, pending :

(i) an appropriate transboundary environmental impact assessment,
which takes account of all potential significant adverse impacts on

Costa Rican territory, carried out by Nicaragua and provided to
Costa Rica;
(ii) formal written notification to Costa Rica of further dredging plans
in the vicinity of Delta Costa Rica and in the lower San Juan
River, not less than three months prior to the implementation of

any such plans ; and
(iii) due consideration of any comments made by Costa Rica upon
receipt of said notification ;

(c) make reparation in the form of compensation for the material damage
caused to Costa Rica, including but not limited to :

(i) damage arising from the construction of artificial caños and
destruction of trees and vegetation on the ‘disputed territory’ ;

23

5 Ord 1088.indb 43 19/10/16 12:01 685 certaines activitésf et construction d’unfe route (arrêt)

ii) les dépenses engagées par le Costa Rica pour remédier à ces dom -
mages, notamment, mais non exclusivement, pour procéder à la
fermeture du caño oriental construit par le Nicaragua en 2013,
conformément au point 2) E) du paragraphe 59 de l’ordonnance en

indication de mesures conservatoires rendue par la Cour le
22 novembre 2013 ;
le montant de cette indemnisation devant être déterminé lors d’fune
phase distincte de la procédure ;

d) d’apporter réparation, par voie de satisfaction, pour remédier pleine -
ment au préjudice causé au Costa Rica, selon des modalités déterminées
par la Cour ;

e) de fournir des assurances et garanties appropriées de non -répétition du
comportement illicite du Nicaragua, selon des modalités déterminéfes
par la Cour et
f) de s’acquitter, sur la base d’une obligation d’indemnisation complète,
de tous les frais engagés par le Costa Rica dans le cadre de la procédure

de demande en indication de mesures conservatoires qui s’est conclue f
par le prononcé de l’ordonnance du 22 novembre 2013, à savoir notam -
ment, mais non exclusivement, les honoraires et frais de ses conseils etf
experts, majorés d’intérêts. »

Au nom du Gouvernement du Nicaragua,

à l’audience du 29 avril 2015 :
«Conformément à l’article 60 du Règlement de la Cour et sur le fondement
des moyens qu’elle a présentés au cours de la procédure éfcrite et de la procédure

orale en l’espèce, la République du Nicaragua prie respectueusefment la Cour :
a) de rejeter les demandes et conclusions présentées par la Républfique du

Costa Rica ;
b) de dire et juger que :

i) le Nicaragua jouit de la pleine souveraineté sur le caño reliant la
lagune de Harbor Head au fleuve San Juan proprement dit, dont la
rive droite constitue la frontière terrestre établie par le traitéf de limites
de 1858, tel qu’interprété par les sentences Cleveland et Alexafnder ;
ii) le Costa Rica est tenu de respecter la souveraineté et l’intégrité tefr-

ritoriale du Nicaragua, en observant les frontières délimitées fpar le
traité de 1858, tel qu’interprété par les sentences Clevelanfd et
Alexander ;
iii) le Nicaragua a le droit, conformément au traité de 1858 tel qu’finter -

prété par les sentences arbitrales ultérieures, d’effectuer fles travaux
qu’il estime opportuns pour améliorer la navigabilité du fleufve
San Juan, y compris des travaux de dragage ;

iv) les seuls droits dont le Costa Rica peut se prévaloir sur le fleuve

San Juan de Nicaragua sont ceux définis par ledit traité, tel qu’inf -
terprété par les sentences Cleveland et Alexander.»

*

50. Dans sa requête en l’affaire Nicaragua c. Costa Rica, le Nicaragua a for -
mulé les demandes suivantes :

24

5 Ord 1088.indb 44 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 685

(ii) the cost of the remediation measures carried out by Costa Rica in
relation to those damages, including but not limited to those taken
to close the eastern caño constructed by Nicaragua in 2013, pur -
suant to paragraph 59 (2) (E) of the Court’s Order on provisional

measures of 22 November 2013;

the amount of such compensation to be determined in a separate
phase of these proceedings ;

(d) provide satisfaction so to achieve full reparation of the injuries causefd
to Costa Rica in a manner to be determined by the Court ;

(e) provide appropriate assurances and guarantees of non -repetition of
Nicaragua’s unlawful conduct, in such a form as the Court may order ;
and
(f) pay all of the costs and expenses incurred by Costa Rica in requesting
and obtaining the Order on provisional measures of 22November 2013,

including, but not limited to, the fees and expenses of Costa Rica’s
counsel and experts, with interest, on a full indemnity basis.”

On behalf of the Government of Nicaragua,

at the hearing of Wednesday 29 April 2015:
“In accordance with Article 60 of the Rules and the reasons given during the
written and oral phase of the pleadings the Republic of Nicaragua respecftfully

requests the Court to :
(a) dismiss and reject the requests and submissions of the Republic of

Costa Rica ;
(b) adjudge and declare that :

(i) Nicaragua enjoys full sovereignty over the caño joining Harbor
Head Lagoon with the San Juan River proper, the right bank of
which constitutes the land boundary as established by the
1858Treaty as interpreted by the Cleveland and Alexander Awards ;
(ii) Costa Rica is under an obligation to respect the sovereignty and

territorial integrity of Nicaragua, within the boundaries delimited
by the 1858 Treaty of Limits as interpreted by the Cleveland and
Alexander Awards;
(iii) Nicaragua is entitled, in accordance with the 1858 Treaty as inter -

preted by the subsequent arbitral awards, to execute works to
improve navigation on the San Juan River as it deems suitable,
and that these works include the dredging of the San Juan de Nic-
aragua River ;
(iv) the only rights enjoyed by Costa Rica on the San Juan de Nicara-

gua River are those defined by said Treaty as interpreted by the
Cleveland and Alexander Awards.”

*

50. In its Application filed in the Nicaragua v. Costa Rica case, Nicaragua
made the following claims :

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5 Ord 1088.indb 45 19/10/16 12:01 686 certaines activitésf et construction d’unfe route (arrêt)

«Sur la base de l’exposé des faits et des moyens juridiques qui préfcède,
le Nicaragua, tout en se réservant le droit de compléter ou de modfifier la
présente requête, prie la Cour de dire et juger que le CostaRica a méconnu:

a) l’obligation lui incombant de ne pas violer l’intégrité du tferritoire nica-
raguayen tel que délimité par le traité de limites de1858, la sentence Cle-
veland de 1888 et les cinq sentences rendues par l’arbitre E.P. Alexander

les 30 septembre 1897, 20 décembre 1897, 22 mars 1898, 26 juillet1899
et 10 mars 1900, respectivement ;
b) l’obligation lui incombant de ne pas causer de dommages au territoiref
nicaraguayen;
c) les obligations lui incombant en vertu du droit international général et

des conventions pertinentes en matière de protection de l’environnfe -
ment, dont la convention de Ramsar sur les zones humides, l’accord sufr
les zones frontalières protégées entre le Nicaragua et le Costaf Rica
(accord sur le système international de zones protégées pour lfa paix
(SIAPAZ)), la convention sur la diversité biologique et la conventfion

concernant la conservation de la biodiversité et la protection des zofnes
prioritaires de faune et de flore sauvages d’Amérique centrale.

En outre, le Nicaragua prie la Cour de dire et juger que le Costa Rica
doit:

a) rétablir lestatu quo ante ;
b) l’indemniser pour tous les dommages causés, en prenant notamment àf
sa charge les frais supplémentaires de dragage du San Juan;
c) s’abstenir de mettre en chantier tout nouveau projet dans la région sans

avoir procédé à une évaluation appropriée de l’impact ftransfrontière sur
l’environnement, évaluation qui devra être soumise en temps vouflu au
Nicaragua pour lui permettre de l’analyser et d’y réagir.

Enfin, le Nicaragua prie la Cour de dire et juger que le Costa Rica doit :

a) cesser tous les travaux de construction engagés qui portent atteinte,f ou
sont susceptibles de porter atteinte, aux droits du Nicaragua ;
b) réaliser, et lui soumettre, une évaluation de l’impact sur l’fenvironnement
adéquate, comprenant tout le détail des travaux. »

51. Au cours de la procédure écrite en l’affaire Nicaragua c. Costa Rica, les
conclusions ci-après ont été présentées par les Parties :

Au nom du Gouvernement du Nicaragua ,

dans le mémoire :
«1. Pour les raisons exposées dans le présent mémoire, la Répfublique du

Nicaragua prie la Cour de dire et juger que, par ses agissements, le Cosfta
Rica a violé :

i) l’obligation lui incombant de ne pas porter atteinte à l’intéfgrité du ter-
ritoire nicaraguayen tel que délimité par le traité de limites fde 1858, la
sentence Cleveland de 1888 et les cinq sentences rendues par l’ar -
bitre E. P. Alexander les 30 septembre 1897, 20 décembre 1897,

22 mars 1898, 26 juillet 1899 et 10 mars 1900, respectivement;
ii) l’obligation lui incombant de ne pas causer de dommages au territoiref
nicaraguayen ;

25

5 Ord 1088.indb 46 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 686

“On the basis of the foregoing statement of facts and law, Nicaragua,f
while reserving the right to supplement, amend or modify this Applicatiofn,
requests the Court to adjudge and declare that Costa Rica has breached :

(a) its obligation not to violate Nicaragua’s territorial integrity as deflim
ited by the 1858 Treaty of Limits, the Cleveland Award of 1888 and
the five Awards of the Umpire E. P. Alexander of 30 September 1897,

20 December 1897, 22 March 1898, 26 July 1899 and 10 March 1900;

(b) its obligation not to damage Nicaraguan territory ;

(c) its obligations under general international law and the relevant enviro-f

mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua
and Costa Rica (International System of Protected Areas for
Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and

Protection of the Main Wildlife Areas [Priority Wilderness Areas] in
Central America.

Furthermore, Nicaragua requests the Court to adjudge and declare that
Costa Rica must :

(a) restore the situation to the status quo ante ;
(b) pay for all damages caused including the costs added to the dredging
of the San Juan River ;
(c) not undertake any future development in the area without an appro -

priate transboundary environmental impact assessment and that this
assessment must be presented in a timely fashion to Nicaragua for its
analysis and reaction.

Finally, Nicaragua requests the Court to adjudge and declare that Costa f
Rica must:

(a) cease all the constructions underway that affect or may affect the rightfs
of Nicaragua;
(b) produce and present to Nicaragua an adequate environmental impact
assessment with all the details of the works.”

51. In the course of the written proceedings in the Nicaragua v. Costa Rica
case, the following submissions were presented by the Parties :

On behalf of the Government of Nicaragua,

in the Memorial :
“1. For the reasons given herein, the Republic of Nicaragua requests fthe

Court to adjudge and declare that, by its conduct, Costa Rica has breached:

(i) its obligation not to violate the integrity of Nicaragua’s territory fas
delimited by the 1858 Treaty of Limits, the Cleveland Award of 1888
and the five Awards of the Umpire E. P. Alexander of 30 Septem-
ber 1897, 20 December 1897, 22 March 1898, 26 July 1899 and

10 March 1900;
(ii) its obligation not to damage Nicaraguan territory ;

25

5 Ord 1088.indb 47 19/10/16 12:01 687 certaines activitésf et construction d’unfe route (arrêt)

iii) les obligations lui incombant au titre du droit international généfral et
des conventions applicables en matière de protection de l’environne -
ment, dont la convention de Ramsar relative aux zones humides, l’ac -
cord sur les zones frontalières protégées entre le Nicaragua etf le

Costa Rica (accord sur le système international de zones protégées pfour
la paix (SIAPAZ)), laconvention sur la diversité biologique et la conven-
tion concernant la conservation de la biodiversité et la protection dfes
zones prioritaires de faune et de flore sauvages d’Amérique centrale.

2. Le Nicaragua prie également la Cour de dire et juger qu’il incombef
au Costa Rica :

i) de mettre fin à tous les travaux de construction en cours qui portentf
atteinte ou sont susceptibles de porter atteinte aux droits du Nicaraguaf ;

ii) de rétablir le statu quo ante ;
iii) del’indemniser pour tous les dommages causés, en prenant notamment
à sa charge les frais supplémentaires de dragage du fleuve San Juan, le
montant de l’indemnisation restant à déterminer à un stade ufltérieur de

la procédure;
iv) de s’abstenir de poursuivre ou de mettre en chantier tout nouveau prof -
jet dans la région sans avoir procédé à une évaluation apfpropriée de
l’impact transfrontière sur l’environnement, dont les résultats devront
être soumis en temps voulu au Nicaragua pour lui permettre de les anaf-

lyser et d’y réagir.

3. La République du Nicaragua prie en outre la Cour de dire et juger :

i) que le Nicaragua est en droit, conformément au traité de 1858, selon
l’interprétation qui en a été faite par les sentences arbitrfales ultérieures,
d’effectuer les travaux qu’il estime opportuns pour améliorer lfa naviga-
bilité du fleuve San Juan, y compris des travaux de dragage visant à
lutter contre la sédimentation et les autres obstacles à la navigaftion;

ii) que, ce faisant, le Nicaragua a le droit de rétablir les conditions dfe nav-i
gabilité qui existaient à l’époque de la conclusion du traitfé de 1858;
iii) que, au vu des violations du traité de1858 et de nombreuses autres règles
de droit international commises par le Costa Rica, le Nicaragua a le
droit de prendre des contre -mesures appropriées, et notamment de

suspendre le droit de navigation sur le fleuve San Juan de Nicaragua
conféré au Costa Rica.

4. Enfin, le Nicaragua prie la Cour d’ordonner au Costa Rica de prendre
immédiatement les mesures d’urgence préconisées par ses propfres experts
et exposées en détail dans le rapport Kondolf, afin de contenir ou d’atté -
nuer le dommage qui continue d’être causé au fleuve San Juan de Nicara-
gua et au milieu environnant.

Si le Costa Rica ne décide pas lui -même de prendre ces mesures, et si la
Cour estime qu’elle ne peut rendre une ordonnance en ce sens que si lfa
procédure prévue aux articles 73 et suivants de son Règlement a été inté -
gralement suivie, la République du Nicaragua se réserve le droit dfe sollici-
ter des mesures conservatoires au titre de l’article 41 du Statut et

conformément à la procédure y afférente visée aux articlefs73 et suivants du
Règlement, ainsi que d’amender et de modifier les présentes confclusions à
la lumière des autres pièces de procédure qui seront déposéfes en l’affaire. »

26

5 Ord 1088.indb 48 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 687

(iii) its obligations under general international law and the relevant environ-f
mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua
and Costa Rica (International System of Protected Areas for

Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and
Protection of the Main Wildlife Sites [Priority Wilderness Areas] in
Central America.

2. Furthermore, Nicaragua requests the Court to adjudge and declare
that Costa Rica must :

(i) cease all the constructions underway that affects or may affect the rights
of Nicaragua;

(ii) restore the situation to thestatus quo ante;
(iii) compensate for all damages caused including the costs added to the
dredging of the San Juan de Nicaragua River, with the amount of the
compensation to be determined in a subsequent phase of the case ;

(iv) not to continue or undertake any future development in the area with -
out an appropriate transboundary environmental impact assessment
and that this assessment must be presented in a timely fashion to Nica -
ragua for its analysis and reaction.

3. The Republic of Nicaragua further requests the Court to adjudge and
declare that:

(i) Nicaragua is entitled, in accordance with the 1858Treaty as interpreted
by the subsequent arbitral awards, to execute works to improve navi -
gation on the San Juan River as it deems suitable, and that these works f
include the dredging of the San Juan de Nicaragua River to remove
sedimentation and other barriers to navigation ; and,

(ii) in so doing, Nicaragua is entitled to re -establish the conditions of nav-
igation that existed at the time the 1858 Treaty was concluded ;
(iii) that the violations of the 1858Treaty and under many rules of interna-
tional law by Costa Rica, allow Nicaragua to take appropriate
countermeasures including the suspension of Costa Rica’s right of nav-

igation in the San Juan de Nicaragua River.

4. Finally, Nicaragua requests the Court to order Costa Rica to imme-
diately take the emergency measures recommended by its own experts and
further detailed in the Kondolf Report, in order to alleviate or mitigatfe the
continuing damage being caused to the San Juan de Nicaragua River and
the surrounding environment.

If Costa Rica does not of itself proceed to take these measures and the
Court considers it cannot order that it be done without the full procedufre
contemplated in Articles 73 et seq. of the Rules of Court, the Republic of
Nicaragua reserves its right to request provisional measures on the basifs of
Article 41 of the Statute and the pertinent procedures of Article 73 and ff.

of the Rules of Court and to amend and modify these submissions in the
light of the further pleadings in this case.”

26

5 Ord 1088.indb 49 19/10/16 12:01 688 certaines activitésf et construction d’unfe route (arrêt)

dans la réplique :
« Pour les raisons exposées dans son mémoire et dans la présente f

réplique, la République du Nicaragua prie la Cour de dire et jugerf que, par
ses agissements, la République du Costa Rica a violé :
i) l’obligation lui incombant de ne pas porter atteinte à l’intéfgrité du ter -

ritoire nicaraguayen, délimité par le traité de limites de 1858, selon l’in-
terprétation qui en a été faite par la sentence Cleveland de 1888 et les
cinq sentences rendues par l’arbitre E. P. Alexander les 30 sep-
tembre 1897, 20 décembre 1897, 22 mars 1898, 26 juillet 1899 et 10 mars
1900, respectivement;

ii) l’obligation lui incombant de ne pas causer de dommages au territoiref
nicaraguayen ;
iii) les obligations lui incombant au titre du droit international généfral et des
conventions applicables en matière de protection de l’environnemenft,
dont la convention de Ramsar relative aux zones humides, l’accord sur

les zones frontalières protégées entre le Nicaragua et le Costaf Rica
(accord sur le système international de zones protégées pour la paix
(SIAPAZ)), la convention sur la diversité biologique et la convention
concernant la conservation de la biodiversité et la protection des
zones prioritaires de faune et de flore sauvages d’Amérique centrale.

2. Le Nicaragua prie également la Cour de dire et juger qu’il incombef
au Costa Rica :

i) de mettre fin à tous les faits internationalement illicites en cours fqui
portent atteinte ou sont susceptibles de porter atteinte aux droits du
Nicaragua;

ii) de rétablir, dans la mesure du possible, le statu quo ante, en respectant
pleinement la souveraineté du Nicaragua sur le fleuveSan Juan de Nica -
ragua, notamment en prenant les mesures d’urgence nécessaires pourf
contenir ou atténuer le dommage qui continue d’être causé auf fleuve et
au milieu environnant ;

iii) de l’indemniser pour tous les dommages causés, s’il n’y est pas remédié
par voie de restitution, en prenant notamment à sa charge les frais sfup -
plémentaires de dragage du fleuve San Juan, le montant de l’indemnisa-
tion restant à déterminer à un stade ultérieur de la procéfdure.

3. En outre, le Nicaragua prie la Cour de dire et juger qu’il incombe auf
Costa Rica de s’abstenir :

i) de mettre en chantier tout nouveau projet dans la région sans avoir
procédé à une évaluation appropriée de l’impact transfrontière sur l’en -
vironnement, dont les résultats devront être soumis en temps vouluf au
Nicaragua pour lui permettre de les analyser et d’y réagir ;
ii) d’utiliser la route1856 pour transporter des matières dangereuses tant

qu’il n’aura pas fourni des garanties que la route est conforme aufx règles
de l’art en matière de construction et aux normes régionales et interna -
tionales les plus strictes en matière de sécurité routière dans des condi -
tions semblables.

4. La République du Nicaragua demande en outre à la Cour de dire et
juger que le Nicaragua est en droit :

i) conformément au traité de 1858, selon l’interprétation qui en a été faite
par les sentences arbitrales ultérieures, d’effectuer des travaux fpour amé -

27

5 Ord 1088.indb 50 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 688

in the Reply :
“For the reasons given in its Memorial and in this Reply, the Republifc

of Nicaragua requests the Court to adjudge and declare that, by its condfuct,
the Republic of Costa Rica has breached :
(i) its obligation not to violate the integrity of Nicaragua’s territory fas

delimited by the 1858 Treaty of Limits as interpreted by the Cleveland
Award of 1888 and the five Awards of the Umpire E. P. Alexander of
30 September 1897, 20 December 1897, 22 March 1898, 26 July 1899,
and 10 March 1900 ;

(ii) its obligation not to damage Nicaraguan territory ;

(iii) its obligations under general international law and the relevant environ-f
mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua

and Costa Rica (International System of Protected Areas for
Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and
Protection of the Main Wildlife Sites [Priority Wilderness Areas] in
Central America.

2. Nicaragua also requests the Court to adjudge and declare that
Costa Rica must:

(i) cease all its continuing internationally wrongful acts that affect or arfe
likely to affect the rights of Nicaragua ;

(ii) inasmuch as possible, restore the situation to the status quo ante, in full
respect of Nicaragua’s sovereignty over the San Juan de Nicaragua
River, including by taking the emergency measures necessary to allevi -
ate or mitigate the continuing harm being caused to the river and the
surrounding environment;

(iii) compensate for all damages caused insofar as they are not made good
by restitution, including the costs added to the dredging of the San Juafn
de Nicaragua River, with the amount of the compensation to be deter -
mined in a subsequent phase of the case.

3. Furthermore, Nicaragua requests the Court to adjudge and declare
that Costa Rica must:

(i) not undertake any future development in the area without an appro -
priate transboundary environmental impact assessment and that this
assessment must be presented in a timely fashion to Nicaragua for its
analysis and reaction ;
(ii) refrain from using Route 1856 to transport hazardous material as long

as it has not given the guarantees that the road complies with the best f
construction practices and the highest regional and international stand -
ards of security for road traffic in similar situations.

4. The Republic of Nicaragua further requests the Court to adjudge and
declare that Nicaragua is entitled :

(i) in accordance with the 1858 Treaty as interpreted by the subsequent
arbitral awards, to execute works to improve navigation on the San

27

5 Ord 1088.indb 51 19/10/16 12:01 689 certaines activitésf et construction d’unfe route (arrêt)

liorer la navigabilité du fleuve San Juan, y compris des travaux de
dragage visant à lutter contre la sédimentation et les autres obstfacles à
la navigation;
ii) ce faisant, de rétablir les conditions de navigabilité envisagéfes dans le

traité de 1858.
5. Enfin, dans l’hypothèse où la Cour n’aurait pas déjà nfommé un

expert impartial au moment de prononcer son arrêt, le Nicaragua la prfie
d’en désigner un pour conseiller les Parties dans l’exécutiofn de celui -ci.

Au nom du Gouvernement du Costa Rica,
dans le contre-mémoire :

«Pour les raisons exposées ci -dessus et tout en se réservant le droit de
compléter, préciser ou modifier les présentes conclusions, le Costa Rica
prie la Cour de rejeter la totalité des prétentions du Nicaragua efn l’espèce.»

dans la duplique :

«Pour les raisons exposées ci -dessus et tout en se réservant le droit de
compléter, préciser ou modifier les présentes conclusions, le Costa Rica
prie la Cour de rejeter la totalité des prétentions du Nicaragua efn l’espèce. »

52. Lors de la procédure orale dans les instances jointes, les conclusionfs
ciaprès ont été présentées par les Parties en l’affaire fNicaragua c. Costa Rica :

Au nom du Gouvernement du Nicaragua,
à l’audience du 30 avril 2015 :

«1. Conformément à l’articl60 du Règlement de la Cour et sur le fon -
dement des moyens exposés au cours de la procédure écrite et def la procé-

dure orale en l’espèce, la République du Nicaragua prie la Cour de dire et
juger que, par ses agissements, la République du Costa Rica a violé :

i) l’obligation lui incombant de ne pas porter atteinte à l’intéfgrité du territoire
nicaraguayen, délimité par le traité de limites d1e858, selon l’interprétation
qui en a été faite par la sentence Cleveland de 1888 et les cinq sentences
rendues par l’arbitre E. P. Alexander les 30 septembre 1897, 20 décembre
1897, 22mars 1898, 26juillet 1899 et10 mars 1900, respectivement ;

ii) l’obligation lui incombant de ne pas causer de dommages au territoiref
nicaraguayen;
iii) les obligations lui incombant au titre du droit international généfral et
des conventions applicables en matière de protection de l’environne -
ment, dont la convention de Ramsar relative aux zones humides, l’ac -

cord sur les zones frontalières protégées entre le Nicaragua etf le
Costa Rica (accord sur le système international de zones protégées pfour
la paix [SIAPAZ]), la convention sur la diversité biologique et la cfonve-n
tion concernant la conservation de la biodiversité et la protection dfes

zones prioritaires de faune et de flore sauvages d’Amérique centrale.
2. Le Nicaragua prie également la Cour de dire et juger qu’il incombef

au Costa Rica :

i) de mettre fin à tous les faits internationalement illicites en cours fqui
portent atteinte ou sont susceptibles de porter atteinte aux droits du
Nicaragua ;

28

5 Ord 1088.indb 52 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 689

Juan River and that these works include the dredging of the San Juan
de Nicaragua River to remove sedimentation and other barriers to nav-
igation ; and,
(ii) in so doing, to reestablish the conditions of navigation foreseen in the

1858 Treaty.
5. Finally, if the Court has not already appointed a neutral expert at the f

time when it adopts its Judgment, Nicaragua requests the Court to appoinft
such an expert who could advise the Parties in the implementation of thef
Judgment.”

On behalf of the Government of Costa Rica,
in the Counter -Memorial :

“For these reasons, and reserving the right to supplement, amplify orf
amend the present submissions, Costa Rica requests the Court to dismiss
all of Nicaragua’s claims in this proceeding.”

in the Rejoinder :

“For these reasons, and reserving the right to supplement, amplify orf
amend the present submissions, Costa Rica requests the Court to dismiss
all of Nicaragua’s claims in this proceeding.”

52. At the oral proceedings in the joined cases, the following submissions
were presented by the Parties in the Nicaragua v. Costa Rica case:

On behalf of the Government of Nicaragua,
at the hearing of 30 April 2015:

“1. In accordance with Article 60 of the Rules and the reasons given
during the written and oral phase of the pleadings the Republic of Nicarfa -

gua respectfully requests the Court to adjudge and declare that, by its fcon-
duct, the Republic of Costa Rica has breached :

(i) its obligation not to violate the integrity of Nicaragua’s territory fas
delimited by the 1858 Treaty of Limits as interpreted by the Cleveland
Award of 1888 and the five Awards of the Umpire E. P. Alexander of
30 September 1897, 20 December 1897, 22 March 1898, 26 July 1899,
and 10 March 1900 ;

(ii) its obligation not to damage Nicaraguan territory ;

(iii) its obligations under general international law and the relevant environ-f
mental conventions, including the Ramsar Convention on Wetlands,
the Agreement over the Border Protected Areas between Nicaragua

and Costa Rica (International System of Protected Areas for
Peace [SI-A-PAZ] Agreement), the Convention on Biological Diver -
sity and the Convention for the Conservation of the Biodiversity and
Protection of the Main Wildlife Sites in Central America.

2. Nicaragua also requests the Court to adjudge and declare that

Costa Rica must:

(i) cease all its continuing internationally wrongful acts that affect or arfe
likely to affect the rights of Nicaragua ;

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5 Ord 1088.indb 53 19/10/16 12:01 690 certaines activitésf et construction d’unfe route (arrêt)

ii) de rétablir, dans la mesure du possible, le statu quo ante, en respectant
pleinement la souveraineté du Nicaragua sur le fleuve SanJuan de Nica-

ragua, notamment en prenant les mesures d’urgence nécessaires pourf
contenir ou atténuer le dommage qui continue d’être causé auf fleuve et
au milieu environnant ;
iii) de l’indemniser pour tous les dommages causés, s’il n’y est fpas remédié
par voie de restitution, en prenant notamment à sa charge les frais sfup -
plémentaires de dragage du fleuve San Juan de Nicaragua, le montant de

l’indemnisation restant à déterminer à un stade ultérieurf de la procédure.
3. En outre, le Nicaragua prie la Cour de dire et juger qu’il incombe auf
Costa Rica de s’abstenir :

i) de mettre en chantier tout nouveau projet dans la région sans avoir
procédé à une évaluation appropriée de l’impact transfrontière sur l’en -
vironnement, dont les résultats devront être soumis en temps vouluf au

Nicaragua pour lui permettre de les analyser et d’y réagir ;
ii) d’utiliser la route856 pour transporter des matières dangereuses tant
qu’il n’aura pas fourni des garanties que la route est conforme aufx règles
de l’art en matière de construction et aux normes régionales et interna -
tionales les plus strictes en matière de sécurité routière dans des condi -
tions semblables.

4. La République du Nicaragua demande en outre à la Cour de dire et
juger que le Nicaragua est en droit :

i) conformément au traité de1858, selon l’interprétation qui en a été faite par
les sentences arbitrales ultérieures, d’effectuer des travaux pourf améliorer la
navigabilité du fleuve SanJuan, ycompris des travaux de dragage visant à
lutter contre la sédimentation et les autres obstacles à la navigaftion.

Au nom du Gouvernement du Costa Rica,
er
à l’audience du 1 mai 2015: «Sur le fondement des moyens exposés au cours de
la procédure écrite et de la procédure orale, le Costa Rica prie la Cour de rejeter
la totalité des prétentions du Nicaragua en l’espèce. »

*
* *

53. La Cour s’intéressera tout d’abord aux éléments communs afux
deux affaires. Elle se penchera ainsi, dans une première partie, sur fla que-s

tion de sa compétence, avant de rappeler, dans une deuxième partief, le
contexte géographique et historique ainsi que la genèse des difféfrends.
La Cour examinera ensuite tour à tour, dans deux parties distinctes, fles

questions en litige en l’affaire Costa Rica c. Nicaragua et en l’affaire Nica‑
ragua c. Costa Rica.

I. Compétence de la Cour

54. En ce qui concerne l’affaire Costa Rica c. Nicaragua, la Cour rap -
pelle que le Costa Rica invoque, comme bases de compétence, l’ar -

ticle XXXI du pacte de Bogotá et les déclarations par lesquelles les Parties

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5 Ord 1088.indb 54 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 690

(ii) inasmuch as possible, restore the situation to the status quo ante, in full
respect of Nicaragua’s sovereignty over the San Juan de Nicaragua

River, including by taking the emergency measures necessary to allevi -
ate or mitigate the continuing harm being caused to the river and the
surrounding environment;
(iii) compensate for all damages caused insofar as they are not made good
by restitution, including the costs added to the dredging of the San Juafn
de Nicaragua River, with the amount of the compensation to be deter -

mined in a subsequent phase of the case.
3. Furthermore, Nicaragua requests the Court to adjudge and declare
that Costa Rica must :

(i) not undertake any future development in the area without an appro -
priate transboundary environmental impact assessment and that this
assessment must be presented in a timely fashion to Nicaragua for its

analysis and reaction ;
(ii) refrain from using Route 1856 to transport hazardous material as long
as it has not given the guarantees that the road complies with the best f
construction practices and the highest regional and international stand-
ards of security for road traffic in similar situations.

4. The Republic of Nicaragua further requests the Court to adjudge and
declare that Nicaragua is entitled :

(i) in accordance with the 1858Treaty as interpreted by the subsequent arbi-
tral awards, to execute works to improve navigation on the San Juan Rivefr
and that these works include the dredging of the San Juan de Nicaragua
River to remove sedimentation and other barriers to navigation.”

On behalf of the Government of Costa Rica,

at the hearing of 1 May 2015: “For the reasons set out in the written and oral
pleadings, Costa Rica requests the Court to dismiss all of Nicaragua’s claims in
this proceeding.”

*
* *

53. The Court will begin by dealing with the elements common to both
cases. It will thus address, in a first part, the question of its jurisdfiction,

before recalling, in a second part, the geographical and historical contfext
and the origin of the disputes.
The Court will then examine in turn, in two separate parts, the dis -

puted issues in the Costa Rica v. Nicaragua case and in the Nicaragua v.
Costa Rica case.

I. Jurisdiction of the Coufrt

54. With regard to the Costa Rica v. Nicaragua case, the Court recalls
that Costa Rica invokes, as bases of jurisdiction, Article XXXI of the

Pact of Bogotá and the declarations by which the Parties have recognifzed

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ont reconnu la compétence obligatoire de la Cour conformément aux f
paragraphes 2 et 5 de l’article 36 du Statut (voir le paragraphe2 ci-dessus).

Elle observe que le Nicaragua ne conteste pas sa compétence pour
connaître des demandes du Costa Rica.
La Cour considère qu’elle a compétence pour connaître du diffférend.
55. S’agissant de l’affaireNicaragua c. Costa Rica, la Cour note que le
Nicaragua invoque à son tour, comme bases de compétence, l’article XXXI

du pacte de Bogotá et les déclarations d’acceptation susmentionfnées (voir
le paragraphe 2 ci-dessus). Elle relève par ailleurs que le Costa Rica ne
conteste pas sa compétence pour connaître des demandes du Nicaragufa.
La Cour considère qu’elle a compétence pour connaître du diffférend.

II. Contexte géographiqufe et historique
et genèse des différenfds

56. Le fleuve San Juan coule sur une distance d’environ 205 kilomètres
depuis le lac Nicaragua jusqu’à la mer des Caraïbes. En un point appelé

«Delta Colorado » (ou « Delta Costa Rica »), il bifurque pour donner
naissance, d’une part, au San Juan inférieur, le bras septentrional, qui se
jette dans la mer des Caraïbes à une trentaine de kilomètres enf aval du
point de bifurcation, près de la ville de San Juan de Nicaragua, aupara -
vant connue sous le nom de San Juan del Norte ou Greytown, et, d’autre

part, au fleuve Colorado, le bras méridional et le plus large des dfeux, qui
coule entièrement en territoire costa -ricien avant d’atteindre la mer à
Barra de Colorado, à une vingtaine de kilomètres au sud -est de l’embou -
chure du San Juan inférieur. Les Parties conviennent que le fleuve Colo-
rado recueille actuellement environ 90 % des eaux du San Juan, les 10 %
restants passant dans le cours inférieur de ce dernier.

57. Le territoire situé entre le fleuveColorado et le cours inférieur du
San Juan est communément désigné Isla Calero (environ 150 kilomètres
carrés) et englobe une région plus petite, que le Costa Rica appelle
IslaPortillos et le Nicaragua, Harbor Head (environ 17 kilomètres carrés),
et qui est située au nord de ce qui fut autrefois le fleuve dénommé Taura.

Dans la partie septentrionale d’Isla Portillos se trouve la lagune de
Los Portillos, ainsi que l’appelle le CostaRica, ou lagune de HarborHead,
selon son nom nicaraguayen, laquelle est actuellement séparée de la mer
des Caraïbes par une formation sableuse (voir croquis n o1 p. 692).
58. Isla Calero fait partie de la Humedal Caribe Noreste (zone humide

du nord-est des Caraïbes), qui a été désignée zone humide d’ifmportance
internationale en vertu de la convention de Ramsar par le Costa Rica
en 1996. La région immédiatement adjacente, qui comprend le San Juan
lui-même et une bande de terre de deux kilomètres de large jouxtant laf
rive gauche (nicaraguayenne) de celui -ci, a été désignée zone humide
d’importance internationale au titre de la convention de Ramsar en 2001

par le Nicaragua, sous le nom de Refugio de Vida Silvestre Río San Juan
(réserve naturelle du fleuve San Juan).

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5 Ord 1088.indb 56 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 691

the compulsory jurisdiction of the Court under paragraphs 2 and 5 of
Article 36 of the Statute (see paragraph 2 above). It notes that Nicaragua

does not contest its jurisdiction to entertain Costaica’s claims.

The Court finds that it has jurisdiction over the dispute.
55. With regard to the Nicaragua v. Costa Rica case, the Court notes
that Nicaragua invokes, for its part, as bases of jurisdiction, ArticleXXXI

of the Pact of Bogotá and the above -mentioned declarations of accep -
tance (see paragraph 2 above). It further observes that Costa Rica does
not contest its jurisdiction to entertain Nicaragua’s claims.
The Court finds that it has jurisdiction over the dispute.

II. Geographical and Histforical Context
and Origin of the Disputfes

56. The San Juan River runs approximately 205 km from Lake Nica -
ragua to the Caribbean Sea. At a point known as “Delta Colorado” (for

“Delta Costa Rica”), the San Juan River divides into two branches : the
Lower San Juan is the northerly of these two branches and flows into tfhe
Caribbean Sea about 30 km downstream from the delta, near the town of
San Juan de Nicaragua, formerly known as San Juan del Norte or Grey -
town; the Colorado River is the southerly and larger of the two branches

and runs entirely within Costa Rica, reaching the Caribbean Sea at Barra
de Colorado, about 20 km south -east of the mouth of the Lower San
Juan. The Parties are in agreement that the Colorado River currently
receives approximately 90 per cent of the water of the San Juan River,
with the remaining 10 per cent flowing into the Lower San Juan.

57. The area situated between the Colorado River and the Lower San
Juan is broadly referred to as Isla Calero (approximately 150 sq km).
Within that area, there is a smaller region known to Costa Rica as Isla
Portillos and to Nicaragua as Harbor Head (approximately 17 sq km); it
is located north of the former Taura River. In the north of Isla Portillfos

is a lagoon, called Laguna Los Portillos by Costa Rica and Harbor Head
Lagoon by Nicaragua. This lagoon is at present separated from the
Caribbean Sea by a sandbar (see sketch -map No. 1 p. 692).

58. Isla Calero is part of the Humedal Caribe Noreste (Northeast Carib-

bean Wetland) which was designated by Costa Rica in 1996 as a wetland
of international importance under the Ramsar Convention. The area
immediately adjacent to it — including the San Juan River itself and a
strip of land 2 km in width abutting the river’s left (Nicaraguan) bank—
was designated by Nicaragua as a wetland of international importance
under the Ramsar Convention in 2001 and is known as the Refugio de

Vida Silvestre Río San Juan (San Juan River Wildlife Refuge).

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5 Ord 1088.indb 57 19/10/16 12:01 692 certaines activitésf et construction d’unfe route (arrêt)

W

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31 11° 15’N 11° 0’N 10° 45’N

5 Ord 1088.indb 58 19/10/16 12:01 - 31 -

certain activities afnd construction of a rfoad (judgment) 692

W

83°30′

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11° 15’N 11° 0’N 10° 45’N 31

5 Ord 1088.indb 59 19/10/16 12:01 693 certaines activitésf et construction d’unfe route (arrêt)

59. Les différends qui opposent à présent les Parties s’inscrivefnt dans
un contexte historique remontant aux années 1850. A la suite d’hostilités

ayant eu lieu entre les deux Etats en 1857, les Gouvernements costa -ricien
et nicaraguayen signèrent, le 15 avril 1858, un traité de limites qui fut rati-
fié par le Costa Rica le 16 avril 1858 et par le Nicaragua le 26 avril 1858
(ci-après le «traité de 1858 »). Le traité de 1858 fixait le tracé de la fron -
tière entre le Costa Rica et le Nicaragua depuis l’océan Pacifique jusqu’à

la mer des Caraïbes. Selon l’article II du traité (cité au paragraphe 71
ci-dessous), une partie de la frontière entre les deux Etats longe la rfive
droite (c’est-à-dire costa-ricienne) du San Juan, à partir d’un point situé à
trois milles anglais en aval de Castillo Viejo, petite localité nicara -
guayenne, jusqu’à « l’extrémité de Punta de Castilla, à l’embouchure du
fleuve San Juan » sur la côte caraïbe. L’article VI du traité de 1858 (cité

au paragraphe 133 ci-dessous) établit ledominium et l’imperium du Nica -
ragua sur les eaux du fleuve, tout en reconnaissant au Costa Rica le droit
d’y naviguer librement à des fins de commerce.
60. Après que le Nicaragua eut, en diverses occasions, contesté la valfi-
dité du traité de 1858, le Costa Rica et le Nicaragua signèrentf, le

24 décembre 1886, un autre instrument dans le cadre duquel ils convinrenft
de soumettre la question de la validité du traité de 1858 à l’farbitrage du
président des Etats -Unis d’Amérique, Grover Cleveland. Les Parties
convinrent en outre que, s’il venait à conclure à la validitéf dudit traité, le
président Cleveland devrait également trancher « tous les autres points

d’interprétation douteuse que l’une ou l’autre des parties aura[it] pu rele -
ver dans le traité » [traduction du Greffe]. Le 22 juin 1887, le Nicaragua
communiqua au Costa Rica 11 points d’interprétation douteuse, lesquels
furent par la suite soumis à la décision du président Clevelandf. En 1888,
la sentence Cleveland confirma, en son premier paragraphe, la validité du
traité de 1858 et précisa, au point 1 de son troisième paragraphe, que, sur

la façade atlantique, la ligne frontière entre les deux pays « commen[çait]
à l’extrémité de Punta de Castilla à l’embouchure du fleuve San Juan de
Nicaragua, en leur état respectif au 15 avril 1858 [traduction du Greffe].
La sentence Cleveland régla également les autres points d’interprétationf
douteuse soumis par le Nicaragua, concernant notamment les conditions

dans lesquelles, d’une part, celui -ci était en droit d’effectuer des travaux
d’amélioration visant le San Juan (point 6 du troisième paragraphe, cité
au paragraphe 116 ci-dessous) et, d’autre part, le Costa Rica pouvait
l’empêcher de dévier les eaux du fleuve (point 9 du troisième paragraphe,
cité au paragraphe 116 ci-dessous), ainsi que l’obligation faite au Nicara -

gua de demander, avant d’octroyer des concessions à des fins de cofnstruc -
tion d’un canal à travers son territoire, l’avis du Costa Rica (point 10 du
troisième paragraphe) ou, « dans les cas où la construction du canal por -
terait atteinte [à ses] droits naturels », d’obtenir son consentement
(point 11 du troisième paragraphe [traduction du Greffe]).
61. Comme suite à la sentence Cleveland, le Costa Rica et le Nicaragua

convinrent en 1896, dans le cadre de la convention Pacheco -Matus rela-
tive à la démarcation de la frontière, d’établir deux comfmissions de

32

5 Ord 1088.indb 60 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 693

59. The present disputes between the Parties are set within a historical
context dating back to the 1850s. Following hostilities between the two f

States in 1857, the Governments of Costa Rica and Nicaragua signed on
15 April 1858 a Treaty of Limits, which was ratified by Costa Rica on
16 April 1858 and by Nicaragua on 26 April 1858 (hereinafter the
“1858 Treaty”). The 1858 Treaty fixed the course of the boundary between
Costa Rica and Nicaragua from the Pacific Ocean to the Caribbean Sea.

According to Article II of the Treaty (quoted in paragraph 71 below),
part of the boundary between the two States runs along the right
(Costa Rican) bank of the San Juan River from a point three English
miles below Castillo Viejo, a small town in Nicaragua, to “the end off
Punta de Castilla, at the mouth of the San Juan” on the Caribbean coast.
Article VI of the 1858 Treaty (quoted in paragraph 133 below) estab -

lished Nicaragua’s dominium and imperium over the waters of the river,
but at the same time affirmed Costa Rica’s right of free navigation on the
river for the purposes of commerce.
60. Following challenges by Nicaragua on various occasions to the
validity of the 1858 Treaty, Costa Rica and Nicaragua signed another

instrument on 24 December 1886, whereby the two States agreed to sub -
mit the question of the validity of the 1858 Treaty to the President of the
United States, Grover Cleveland, for arbitration. In addition, the Partifes
agreed that, if the 1858 Treaty were found to be valid, President Cleve-
land should also decide “upon all the other points of doubtful interpreta -

tion which either of the parties may find in the treaty”. On 22 June 1887,
Nicaragua communicated to Costa Rica 11 points of doubtful interpreta-
tion, which were subsequently submitted to President Cleveland for reso -
lution. The Cleveland Award of 1888 confirmed, in its paragraph 1, the
validity of the 1858 Treaty and found, in its paragraph 3 (1), that the
boundary line between the two States on the Atlantic side “begins at the

extremity of Punta de Castilla at the mouth of the San Juan de Nicaraguaf
River, as they both existed on the 15th day of April1858”. The Cleveland
Award also settled the other points of doubtful interpretation submittedf
by Nicaragua, such as the conditions under which Nicaragua may carry
out works of improvement on the San Juan River (para. 3 (6), quoted in

paragraph 116 below), the conditions under which Costa Rica may pre -
vent Nicaragua from diverting the waters of the San Juan (para. 3 (9),
quoted in paragraph 116 below), and the requirement that Nicaragua not
make any grants for the purpose of constructing a canal across its terrif -
tory without first asking for the opinion of Costa Rica (para. 3 (10)) or,

“where the construction of the canal will involve an injury to the natural
rights of Costa Rica”, obtaining its consent (para. 3 (11)).

61. Subsequent to the Cleveland Award, Costa Rica and Nicaragua

agreed in 1896, under the Pacheco -Matus Convention on border demar -
cation, to establish two national Demarcation Commissions, each com -

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démarcation nationales, composées l’une et l’autre de deux mfembres

(art. I). La convention Pacheco-Matus prévoyait par ailleurs que les com-
missions compteraient un ingénieur, désigné par le présidentf des Etats-
Unis d’Amérique, qui « disposera[it]de vastes pouvoirs pour trancher
tout différend susceptible de se faire jour dans le cadre de[s] … opéra-
tions, et [dont l]a décision sera[it] définitive » (art. II [traduction du

Greffe]). C’est ainsi que fut nommé le général américain Edwardf Por-
ter Alexander. Pendant le processus de démarcation, qui commença
en 1897 et s’acheva en 1900, le général Alexander rendit cinq sentences,
dont les trois premières présentent un intérêt particulier pfour l’affaire
Costa Rica c. Nicaragua (voir les paragraphes 73-75 ci-dessous).

62. A partir des années 1980, certaines divergences de vues se firent jour
entre les Parties au sujet de la portée exacte des droits de navigatifon confé
rés par le traité de 1858 au Costa Rica, ce qui amena ce dernier à déposer
devant la Cour une requête introductive d’instance contre le Nicarfagua le
29 septembre 2005. La Cour rendit son arrêt le 13 juillet 2009, lequel a

notamment précisé la portée des droits de navigation du Costa Rica ainsi
que celle du pouvoir du Nicaragua de réglementer la navigation sur le
fleuve San Juan (Différend relatif à des droits de navigation et des droits
connexes (Costa Rica c. Nicaragua), arrêt, C.I.J. Recueil 2009, p. 213).
63. Le 18 octobre 2010, le Nicaragua entreprit le dragage du fleuve

San Juan, afin d’en améliorer la navigabilité. Il effectua égalefmont des tra
vaux dans la partie septentrionale d’IslaPortillos(voir croquis n 1 p. 692).
A cet égard, le CostaRica soutient que le Nicaragua a artificiellement percé
un chenal (les deux Parties appellent «caño» ce type de chenal) sur le terri-
toire costa-ricien, à IslaPortillos entre le fleuve San Juan et la lagune de

Los Portillos/HarborHead ; le Nicaragua affirme s’être borné à dégager un
caño existant sur son territoire. Par ailleurs, le Nicaragua déploya certfaines
formations militaires et d’autres agents dans cette même zone. Le
18 novembre 2010, le Costa Rica déposa sa requête introductive d’instance
en l’affaire Costa Rica c. Nicaragua (voir le paragraphe1 ci-dessus). Il pré-

senta également une demande en indication de mesures conservatoires sfur le
fondement de l’article41 du Statut (voir le paragraphe3 ci-dessus).
64. En décembre 2010, le Costa Rica amorça des travaux en vue de la
construction, sur son territoire, de la route 1856 Juan Rafael Mora Por-
ras (ciaprès la «route»), qui longe une partie de sa frontière avec le Nica-

ragua. La route a une longueur prévue de 159,7 km, depuis Los Chiles, à
l’ouest, jusqu’à un point situé juste au -delà de «Delta Colorado », à l’est.
Elle suit le cours du fleuve San Juan sur 108,2 km (voir croquis n o 2
p. 95). Le 21 février 2011, le Costa Rica prit un décret par lequel était
déclaré l’état d’urgence dans la région frontalièref, ce qui, soutient -il, le

dispensait de l’obligation de mener une évaluation de l’impact fsur l’envi-
ronnement avant de construire la route. Le 22 décembre 2011, le Nicara-
gua déposa sa requête introductive d’instance en l’affaire Nicaragua
c.Costa Rica (voir le paragraphe 9 ci-dessus), alléguant en particulier que
la construction de la route avait entraîné des dommages transfrontfières

importants.

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5 Ord 1088.indb 62 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 694

posed of two members (Art. I). The Pacheco -Matus Convention further
provided that the Commissions would include an engineer, appointed by

the President of the United States of America, who “shall have broad f
powers to decide whatever kind of differences may arise in the course of
any operations and his ruling shall be final” (Art. II). United States Gen-
eral Edward Porter Alexander was so appointed. During the demarcation
process, which began in 1897 and was concluded in 1900, General Alex-

ander rendered five awards, the first three of which are of particular rfel -
evance to the Costa Rica v. Nicaragua case (see paragraphs 73-75 below).

62. Starting in the 1980s, some disagreements arose between Costa Rica
and Nicaragua concerning the precise scope of Costa Rica’s rights of

navigation under the 1858 Treaty. This dispute led Costa Rica to file an
Application with the Court instituting proceedings against Nicaragua on
29 September 2005. The Court rendered its Judgment on 13 July 2009,
which, inter alia, clarified Costa Rica’s navigational rights and the extent
of Nicaragua’s power to regulate navigation on the San Juan River (Dis ‑

pute regarding Navigational and Related Rights (Costa Rica v. Nicara‑
gua), Judgment, I.C.J. Reports 2009, p. 213).
63. On 18 October 2010, Nicaragua started dredging the San Juan
River in order to improve its navigability. It also carried out works inf the
northern part of Isla Portillos (see sketch -map No. 1 p .6 92). In this

regard, Costa Rica contends that Nicaragua artificially created a channel
(both Parties refer to such channels as “caños”) on Costa Rican territory,
in Isla Portillos between the San Juan River and Laguna Los Portillos/
Harbor Head Lagoon, whereas Nicaragua argues that it was only clear -
ing an existing caño on Nicaraguan territory. Nicaragua also sent some
military units and other personnel to that area. On 18 November 2010,

Costa Rica filed its Application instituting proceedings in the CostaRica v.
Nicaragua case (see paragraph 1 above). Costa Rica also submitted a
request for the indication of provisional measures under Article 41 of the
Statute (see paragraph 3 above).
64. In December 2010, Costa Rica started works for the construction of

Route 1856 Juan Rafael Mora Porras (hereinafter the “road”), which runfs
in Costa Rican territory along part of its border with Nicaragua. The
road has a planned length of 159.7 km, extending from Los Chiles in the
west to a point just beyond “Delta Colorado” in the east. For 108.f2 km,
it follows the course of the San Juan River (see sketch -map No. 2

p. 695). On 21 February 2011, Costa Rica adopted an Executive Decree
declaring a state of emergency in the border area, which Costa Rica
maintains exempted it from the obligation to conduct an environmental
impact assessment before constructing the road. On 22 December 2011,
Nicaragua filed its Application instituting proceedings in the Nicaragua v.
Costa Rica case (see paragraph 9 above), claiming in particular that the

construction of the road resulted in significant transboundary harm.

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5 Ord 1088.indb 63 19/10/16 12:01 695 certaines activitésf et construction d’unfe route (arrêt)

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5 Ord 1088.indb 64 19/10/16 12:01 - 34 -
certain activities afnd construction of a rfoad (judgment) 695

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III. Questions en litigef en l’affaire C osta R iCa c. NiCaRagua

A. Souveraineté sur le territoire litigieux
et violations alléguées de celle‑ci

65. Le Costa Rica soutient que le Nicaragua a manqué à

«l’obligation de respecter [s]a souveraineté et [son] intégritéf territo -
riale … selon les frontières définies par le traité de limites de 1858 et
précisées par la commission de démarcation établie en vertu fde

la convention Pacheco-Matus, et en particulier par les première et
deuxième sentences Alexander » (conclusions finales, point 2 b) i)),

se fondant à cet égard sur la prémisse ainsi formulée : « le « territoire liti-
gieux », tel que défini par la Cour dans ses ordonnances des 8 mars 2011
et 22 novembre 2013, relève de la souveraineté de la République du
Costa Rica » (ibid., point 2 a)). Dans ses conclusions finales, il prie la

Cour de trancher également la question de la souveraineté sur le tferritoire
litigieux.
66. Le Costa Rica affirme que le Nicaragua a violé sa souveraineté ter -
ritoriale dans la région d’Isla Portillos, notamment en creusant, en 2010,
un caño destiné à relier le fleuve San Juan à la lagune de Harbor Head, et

en revendiquant une partie du territoire costa -ricien. D’après le
Costa Rica, cette violation de souveraineté a été aggravée par l’établisse -
ment d’une présence militaire dans la région et le creusement efn 2013,
près de l’extrémité septentrionale d’Isla Portillos, de deux autres caños
par le Nicaragua.

67. La Cour constate que les violations supposées avoir été commisefs
en 2013, quoique postérieures au dépôt de la requête, concerfnent des faits
qui sont de la même nature que ceux visés par celle -ci et au sujet desquels
les Parties ont eu la possibilité d’exprimer leurs vues dans leursf plaidoi -
ries. Ces allégations de violation peuvent donc être examinées fpar la Cour

comme faisant partie de la demande. Elles seront également abordéefs plus
loin dans le contexte de l’analyse du respect par le Nicaragua de l’fordon-
nance du 8 mars 2011 portant indication de mesures conservatoires.
68. Le Nicaragua ne nie pas avoir dragué les trois caños, mais soutient
qu’« [il] jouit de la pleine souveraineté sur le caño reliant la lagune de

Harbor Head au fleuve San Juan proprement dit, dont la rive droite
constitue la frontière terrestre établie par le traité de limites de 1858, tel
qu’interprété par les sentences Cleveland et Alexander » (conclusions
finales, point b) i)). Il fait par ailleurs valoir quele Costa Rica est tenu
de respecter [s]a souveraineté et [son] intégrité territoriale … en observant

les frontières délimitées par le traité de1858, tel qu’interprété par les sen-
tences Cleveland et Alexander » (ibid., point b) ii)).
69. Puisqu’il n’est pas contesté que le Nicaragua a mené certaines acti -
vités dans le territoire litigieux, il y a lieu, pour rechercher si lfa souverai -
neté territoriale du Costa Rica a été violée, de déterminer lequel des deux

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III. Issues in theC osta RiCa v.N iCaRagua Case

A. Sovereignty over the Disputed Territory
and Alleged Breaches Thereof

65. Costa Rica submits that Nicaragua breached

“the obligation to respect the sovereignty and territorial integrity fof
the Republic of Costa Rica, within the boundaries delimited by the

1858 Treaty of Limits and further defined by the Demarcation Com -
mission established by the Pacheco -Matus Convention, in particular
by the first and second Alexander Awards” (final submissions,
para. 2 (b) (i)).

This claim is based on the premise that “[s]overeignty over the ‘dfisputed
territory’, as defined by the Court in its Orders of 8 March 2011 and
22 November 2013, belongs to the Republic of Costa Rica” (ibid.,

para. 2 (a)). In its final submissions Costa Rica requested the Court to
make a finding also on the issue of sovereignty over the disputed terri -
tory.
66. Costa Rica alleges that Nicaragua violated its territorial sover -

eignty in the area of Isla Portillos in particular by excavating in 2010f a
caño with the aim of connecting the San Juan River with the Harbor
Head Lagoon and laying claim to Costa Rican territory. According to
Costa Rica, this violation of sovereignty was exacerbated by Nicaragua’s
establishment of a military presence in the area and by its excavation ifn

2013 of two other caños located near the northern tip of Isla Portillos.

67. The Court notes that although the violations that allegedly took
place in 2013 occurred after the Application was made, they concern factfs

which are of the same nature as those covered in the Application and
which the Parties had the opportunity to discuss in their pleadings. Thefse
alleged violations may therefore be examined by the Court as part of thef
merits of the claim. They will later also be considered in relation to Nfica
ragua’s compliance with the Court’s Order on provisional measures fof

8 March 2011.
68. Nicaragua does not contest that it dredged the three caños, but
maintains that “Nicaragua enjoys full sovereignty over the caño joining
Harbor Head Lagoon with the San Juan River proper, the right bank of
which constitutes the land boundary as established by the 1858 Treaty as

interpreted by the Cleveland and Alexander Awards” (final submissionfs,
para. (b) (i)). Nicaragua further submits that “Costa Rica is under an
obligation to respect the sovereignty and territorial integrity of Nicarfa-
gua, within the boundaries delimited by the 1858 Treaty of Limits as

interpreted by the Cleveland and Alexander Awards” (ibid., para. (b) (ii)).
69. Since it is uncontested that Nicaragua conducted certain activities
in the disputed territory, it is necessary, in order to establish whethefr
there was a breach of Costa Rica’s territorial sovereignty, to determine

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Etats a souveraineté sur ce territoire. Dans son ordonnance du8 mars 2011
portant indication de mesures conservatoires, la Cour a défini le «f terri-

toire litigieux » comme « la partie septentrionale [d’]Isla Portillos, soit la
zone humide d’environ trois kilomètres carrés comprise entre la rive
droite du caño litigieux, la rive droite du fleuve San Juan lui-même jusqu’à
son embouchure dans la mer des Caraïbes et la lagune de Harbor Head»
(C.I.J. Recueil 2011 (I), p. 19, par. 55). Le caño dont il est ici question est

celui que le Nicaragua a dragué en 2010. Ce dernier n’a pas contesté cette
définition du « territoirelitigieux»et le Costa Rica l’a expressément adop -
tée dans ses conclusions finales (point 2 a)). La Cour s’en tiendra à la
définition du « territoire litigieux qu’elle a énoncée dans son ordonnance
de 2011. Elle rappelle que, dans son ordonnance en indication de mesures
conservatoires du 22 novembre 2013, elle a précisé qu’un campement

militaire nicaraguayen « se trouv[ant] sur la plage ell-même à la lisière de
la végétation », à proximité d’un des caños dragués en 2013, était « situé
sur le territoire litigieux tel que défini par elle dans son ordonnanfce du
8 mars 2011 » (C.I.J. Recueil 2013, p. 365, par. 46).
70. La définition précitée du « territoire litigieux» ne traite pas spécifi-

quement du segment de la côte caraïbe qui s’étend entre la lfagune de Har -
bor Head, dont les deux Parties admettent qu’elle est nicaraguayenne, et f
l’embouchure du San Juan. Les Parties ont bien, dans leurs plaidoiries,
exprimé des vues divergentes sur ce point, mais elles n’ont pas abfordé la
question de l’emplacement précis de l’embouchure du fleuve, eft n’ont pas

davantage présenté d’information détaillée concernant la fcôte. Elles n’ont
ni l’une ni l’autre demandé à la Cour de préciser le tracfé de la frontière
par rapport à cette côte. La Cour s’abstiendra donc de le fairef.
71. S’agissant du territoire litigieux, les Parties fondent leurs préten -
tions respectives sur le traité de 1858, la sentence Cleveland et les sen -
tences Alexander. L’article II du traité énonce ce qui suit :

«La limite entre les deux républiques, à partir de la mer du Nord, f
partira de l’extrémité de Punta de Castilla, à l’embouchufre du fleuve

San Juan de Nicaragua, puis suivra la rive droite de ce fleuve jusqu’àf
un point distant de trois milles anglais de Castillo Viejo… » [Version
originale en espagnol :« La línea divisoria de las dos Repúblicas, par ‑
tiendo del mar del Norte, comenzará en la extremidad de Punta de
Castilla, en la desembocadura del río de San Juan de Nicaragua, y

continuará marcándose con la márgen derecha del expresado rí▯o, hasta
un punto distante del Castillo Viejo tres millas inglesas… » ]

72. Dans la sentence qu’il a rendue en 1888, le président Cleveland est
parvenu à la conclusion suivante :

«La frontière entre la République du Costa Rica et la République
du Nicaragua du côté de l’Atlantique commence à l’extréfmité de
Punta de Castilla à l’embouchure du fleuve San Juan de Nicaragua,
en leur état respectif au 15 avril 1858. La propriété de tous atterrisse -
ments à Punta de Castilla sera régie par le droit applicable en la

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5 Ord 1088.indb 68 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 697

which State has sovereignty over that territory. The “disputed territfory”
was defined by the Court in its Order of 8 March 2011 on provisional

measures as “the northern part of Isla Portillos, that is to say, thef area of
wetland of some 3 square kilometres between the right bank of the dis -
puted caño , the right bank of the San Juan River up to its mouth at the
Caribbean Sea and the Harbor Head Lagoon” (I.C.J. Reports 2011 (I),
p. 19, para. 55). The caño referred to is the one which was dredged by

Nicaragua in 2010. Nicaragua did not contest this definition of the “fdis -
puted territory”, while Costa Rica expressly endorsed it in its final sub -
missions (para. 2 (a)). The Court will maintain the definition of “disputed
territory” given in the 2011 Order. It recalls that its Order of 22 Novem-
ber 2013 indicating provisional measures specified that a Nicaraguan
military encampment “located on the beach and close to the line of veg -

etation” near one of the caños dredged in 2013 was “situated in the dis -
puted territory as defined by the Court in its Order of 8 March 2011”
(I.C.J. Reports 2013, p. 365, para. 46).

70. The above definition of the “disputed territory” does not specifi-

cally refer to the stretch of coast abutting the Caribbean Sea which liefs
between the Harbor Head Lagoon, which lagoon both Parties agree is
Nicaraguan, and the mouth of the San Juan River. In their oral argu -
ments the Parties expressed different views on this issue. However, theyf
did not address the question of the precise location of the mouth of thef

river nor did they provide detailed information concerning the coast. Nef-i
ther Party requested the Court to define the boundary more precisely witfh
regard to this coast. Accordingly, the Court will refrain from doing so.f
71. In their claims over the disputed territory both Parties rely on the
1858 Treaty, the Cleveland Award and the Alexander Awards. According
to Article II of the Treaty :

“The dividing line between the two Republics, starting from the
Northern Sea, shall begin at the end of Punta de Castilla, at the mouth

of the San Juan de Nicaragua River, and shall run along the right bank
of the said river up to a point three English miles distant from Castillfo
Viejo . . .” [In the Spanish original: “La línea divisoria de las dos Repú
blicas, partiendo del mar del Norte, comenzará en la extremidad de
Punta de Castilla, en la desembocadura del río de San Juan de Nicara ‑

gua, y continuará marcándose con la márgen derecha del expresado río,
hasta un punto distante del Castillo Viejo tres millas inglesas. . .”]

72. In 1888 President Cleveland found in his Award that :

“The boundary line between the Republics of Costa Rica and Nic-
aragua, on the Atlantic side, begins at the extremity of Punta de Cas-
tilla at the mouth of the San Juan de Nicaragua River, as they both
existed on the 15th day of April 1858. The ownership of any accretion
to said Punta de Castilla is to be governed by the laws applicable to

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matière. » (Nations Unies, Recueil des sentences arbitrales (RSA),
vol. XXVIII, p. 209 [traduction du Greffe].)

73. Lorsque les commissions de démarcation furent établies en vertu
de la convention Pacheco-Matus, l’un des membres, qui devait être dési -

gné par le président des Etats -Unis d’Amérique, se vit conférer le pouvoir
de « régler tout différend pouvant voir le jour entre les commissions dfu
Costa Rica et du Nicaragua dans le cadre de leurs opérations » (voir le
paragraphe 61 ci-dessus). Aux termes de la convention, cette personne
« disposera[it] de vastes pouvoirs pour trancher tout différend susceptible

de se faire jour dans le cadre de l’une ou l’autre de ces opéraftions, et sa
décision sera[it] définitive » (art.I, RSA, vol. XXVIII, p. 212 [traduction
du Greffe]). C’est ainsi que le général Alexander, dûment désigné à cet
effet, rendit cinq sentences relatives à la délimitation. Dans la fpremière, il
déclara que la ligne frontière

« d[evait] suivre le bras… appelé le San Juan inférieur, à travers son
port et dans la mer.
L’extrémité naturelle de cette ligne est le promontoire droit dfe l’em-

bouchure du port.» (Ibid., p. 217 [traduction du Greffe].)
Il précisa en outre que,

« dans tout le traité, le fleuve est considéré comme un débofuché en
mer pour le commerce. Cela implique qu’il est considéré dans defs
conditions d’eau moyennes, les seules dans lesquelles il est navi -

gable. » (Ibid., p. 218-219 [traduction du Greffe].)
Il procéda ensuite à la délimitation du premier tronçon de lfa frontière, à
partir de la mer des Caraïbes, dans les termes suivants :

«[L]’emplacement exact où était l’extrémité du promontofire de
Punta de Castillo le 15 avril 1858 est depuis longtemps recouvert par

la mer des Caraïbes et il n’y a pas assez de convergence dans les fcartes
anciennes sur le tracé du rivage pour déterminer avec une certitudfe
suffisante sa distance ou son orientation par rapport au promontoire
actuel. Il se trouvait quelque part au nord -est et probablement à une
distance de 600 à 1600 pieds, mais il est aujourd’hui impossible de le
situer exactement. Dans ces conditions, la meilleure façon de satis -

faire aux exigences du traité et de la sentence arbitrale du pré -
sident Cleveland est d’adopter ce qui constitue en pratique le
promontoire aujourd’hui, à savoir l’extrémité nord -ouest de ce qui
paraît être la terre ferme, sur la rive est de la lagune de HarborfHead.
J’ai en conséquence personnellement inspecté cette zone et je

déclare que la ligne initiale de la frontière sera la suivante:
Son orientation sera nord-est sud-ouest, à travers le banc de sable,
de la mer des Caraïbes aux eaux de la lagune de Harbor Head. Elle
passera au plus près à 300 pieds au nord-ouest de la petite cabane qui

se trouve actuellement dans les parages. En atteignant les eaux de la
lagune de Harbor Head, la ligne frontière obliquera vers la gauche,

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that subject.” (United Nations, Reports of International Arbitral
Awards (RIAA), Vol. XXVIII, p. 209.)

73. When the Commissions on demarcation were established by the
Pacheco-Matus Convention, one member, to be designated by the Presi -

dent of the United States of America, was given the power to “resolve
any dispute between the Commissions of Costa Rica and Nicaragua aris-
ing from the operations” (see paragraph 61 above). According to this
Convention, the said person “shall have broad powers to decide whatevfer
kind of differences may arise in the course of any operations and his rufl -

ing shall be final” (Art. II, RIAA, Vol. XXVIII, p. 212). On this basis,
General Alexander, who had been duly designated to this position, ren -
dered five awards concerning the border. In his first Award he stated thfat
the boundary line :

“must follow the . . . branch . . . called the Lower San Juan, through
its harbor and into the sea.
The natural terminus of that line is the right -hand headland of the

harbor mouth.” (Ibid., p. 217.)
He observed that :

“throughout the treaty the river is treated and regarded as an outletf
of commerce. This implies that it is to be considered as in average
condition of water, in which condition alone it is navigable.” (Ibid.,

pp. 218-219.)
He then defined the initial part of the boundary starting from the Carib -
bean Sea in the following terms :

“The exact spot which was the extremity of the headland of Punta
de Castillo [on] April 15, 1858, has long been swept over by the Car -

ibbean Sea, and there is too little concurrence in the shore outline of f
the old maps to permit any certainty of statement of distance or exact
direction to it from the present headland. It was somewhere to the
north-eastward, and probably between 600 and 1,600 feet distant, but
it can not now be certainly located. Under these circumstances it best
fulfils the demands of the treaty and of President Cleveland’s award f

to adopt what is practically the headland of today, or the north-
western extremity of what seems to be the solid land, on the east side
of Harbor Head Lagoon.

I have accordingly made personal inspection of this ground, and

declare the initial line of the boundary to run as follows, to wit :
Its direction shall be due north-east and south-west, across the bank
of sand, from the Caribbean Sea into the waters of Harbor Head
Lagoon. It shall pass, at its nearest point, 300 feet on the north-west f

side from the small hut now standing in that vicinity. On reaching the
waters of Harbor Head Lagoon the boundary line shall turn to the

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en direction du sud -est, et suivra le rivage autour du port jusqu’à
atteindre le fleuve proprement dit par le premier chenal rencontré.f
Remontant ce chenal et le fleuve proprement dit, la ligne se poursui -
vra comme prescrit dans le traité. » (RSA, vol. XXVIII, p. 220 [tra‑
duction du Greffe].)

A cette première sentence était annexé un croquis représentafnt le tracé de
ce premier tronçon de la frontière dans les conditions géographfiques qui

existaient alors ( ibid., p. 221), sur lequel ce que l’arbitre considérait
comme le « premier chenal » était le bras du San Juan inférieur qui se
jetait alors dans la lagune de Harbor Head (voir croquis n o 3 ci-dessous).
Un croquis plus précis de cette même ligne frontière fut étafbli dans le

cadre des travaux des commissions de démarcation.

74. La deuxième sentence Alexander envisageait la possibilité « non
seulement que [l]es rives [du fleuve San Juan] s’élargissent ou se resser -
r[assent] de manière progressive, mais aussi que ses chenaux [fussentf]
radicalement modifiés ». On y lit l’observation suivante :

«De tels changements, qu’ils soient progressifs ou soudains, auront
nécessairement des incidences sur la ligne frontière actuelle. Maifs,
concrètement, les conséquences ne pourront être déterminéfes qu’en

fonction des circonstances particulières à chaque cas, conforméfment
aux principes du droit international applicables.
Le mesurage et la démarcation proposés de la ligne frontière sefront
sans incidence sur l’application desdits principes. RSA, vol. XXVIII,
p. 224 [traduction du Greffe].)

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left, or south-eastward, and shall follow the water’s edge around the

harbor until it reaches the river proper by the first channel met. Up
this channel, and up the river proper, the line shall continue to ascendf
as directed in the treaty.” (RIAA, Vol. XXVIII, p. 220.)

A sketch illustrating this initial part of the boundary in the geographifc
situation prevailing at the time was attached to this first Award ( ibid.,
p. 221). In that sketch, what the Arbitrator considered to be the “firsft

channel” was the branch of the Lower San Juan River which was then
flowing into the Harbor Head Lagoon (see sketch-map No. 3 below). The
same boundary line was sketched with greater precision in the proceed -
ings of the Commissions on demarcation.

74. The second Alexander Award envisaged the possibility that the
banks of the San Juan River would “not only gradually expand or con -
tract but that there [would] be wholesale changes in its channels”. Tfhe
Arbitrator observed that :

“Today’s boundary line must necessarily be affected in future by
all these gradual or sudden changes. But the impact in each case can

only be determined by the circumstances of the case itself, on a
case-by-case basis in accordance with such principles of international
law as may be applicable.
The proposed measurement and demarcation of the boundary line
will not have any effect on the application of those principles.” (RIAA,

Vol. XXVIII, p. 224.)

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75. Dans sa troisième sentence, le général Alexander soulignait que
« lesfrontières marquées par des voies navigables [étaient] sujettes à varier

lorsque le lit de cellesi v[iendrait] à changer. En d’autres termes, c’[était]
le lit du fleuve qui exer[çait] une influence, et non l’eau qufi se trouv[ait]
entre les rives de ce dernier,au-dessus ou au-dessous de celles-ci. » (RSA,
vol. XXVIII, p. 229.) Telle fut sa conclusion :

«Permettez-moi de résumer brièvement et d’exposer plus claire -
ment la situation dans son ensemble, conformément aux principes
formulés dans ma première sentence, à savoir que, pour interpréter le

traité de 1858 dans la pratique, le San Juan doit être considéré
comme un fleuve navigable. Je décide donc que la ligne de séparaftion
exacte entre les juridictions des deux pays est la rive droite du fleufve,
lorsque l’eau est à son niveau ordinaire et que le fleuve est nafvigable
par des bateaux et des embarcations d’usage général. Lorsque tefl est
le cas, toute partie des eaux du fleuve se trouve sous la juridiction fdu

Nicaragua et toute parcelle de terre située sur la rive droite, sous fcelle
du Costa Rica. » (Ibid., p. 230 [traduction du Greffe].)

76. La Cour estime que le traité de 1858 et les sentences rendues par le f
président Cleveland et le général Alexander amènent à conclure que l’ar -
ticle II dudit traité, qui place la frontière sur la « rive droite d[u] …
fleuve», doit s’interpréter à la lumière de l’article VI (cité en entier au
paragraphe 133 ci -dessous), aux termes duquel « la République du

Costa Rica aura … un droit perpétuel de libre navigation sur les … eaux
[du fleuve], entre l’embouchure [de celui-ci] et un point situé à
trois milles anglais en aval de Castillo Viej». Ainsi que le général Alexan -
der l’a fait observer lorsqu’il a procédé à la démarcaftion de la frontière, le
fleuve est, dans le traité de 1858, considéré, « dans des conditions d’eau
moyennes», comme un « débouché en mer pour le commerce » (voir le

paragraphe 73 ci-dessus). De l’avis de la Cour, il découle des articles II et
VI, lus conjointement, que, pour que la rive droite d’un chenal du flfeuve
constitue la frontière, ce chenal doit être navigable et offrir unf «débouché
en mer pour le commerce ». Il apparaît ainsi que les droits de navigation
du Costa Rica et la souveraineté sur la rive droite, qui a clairement étéf

attribuée à ce dernier jusqu’à l’embouchure du fleuve, fsont liés.
77. Le Costa Rica avance que, si aucun des chenaux du fleuve SanJuan
ne débouche de nos jours dans la lagune de Harbor Head, le lit du chenal
principal de son cours inférieur n’a pas connu de changement important
depuis les sentences Alexander et le territoire situé sur la rive drofite de

celui-ci, jusqu’à son embouchure dans la mer des Caraïbes, devrait être
considéré comme relevant de sa souveraineté. Il ajoute qu’ilf y a lieu de
n’accorder aucune importance à ce qui n’est, selon lui, qu’un caño artifi -
ciel creusé par le Nicaragua en 2010 afin de relier le fleuve San Juan à la
lagune de Harbor Head.
78. De son côté, le Nicaragua affirme que, du fait de l’évolutifon natu -

relle de la géographie du territoire litigieux, le «emier chenal» auquel le
général Alexander faisait référence dans sa première sentence corresponfd

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5 Ord 1088.indb 74 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 700

75. In his third Award, General Alexander noted that “borders delim -
ited by waterways are likely to change when changes occur in the beds off

such waterways. In other words, it is the riverbed that affects changes fand
not the water within, over or below its banks.” ( RIAA, Vol. XXVIII,
p. 229.) He reached the following conclusion :

“Let me sum up briefly and provide a clearer understanding of the
entire question in accordance with the principles set out in my first
award, to wit, that in the practical interpretation of the 1858 Treaty,

the San Juan River must be considered a navigable river. I therefore
rule that the exact dividing line between the jurisdictions of the two
countries is the right bank of the river, with the water at ordinary
stage and navigable by ships and general -purpose boats. At that stage,
every portion of the waters of the river is under Nicaraguan jurisdic -
tion. Every portion of land on the right bank is under Costa Rican

jurisdiction.” (Ibid., p. 230.)

76. The Court considers that the 1858 Treaty and the awards by Presi-
dent Cleveland and General Alexander lead to the conclusion that Arti -
cle II of the 1858 Treaty, which places the boundary on the “right bank
of the . . . river”, must be interpreted in the context of Article VI (quoted
in full at paragraph 133 below), which provides that “the Republic of

Costa Rica shall . . . have a perpetual right of free navigation on the . . .
waters [of the river] between [its] mouth . . . and a point located three
English miles below Castillo Viejo”. As General Alexander observed inf
demarcating the boundary, the 1858 Treaty regards the river, “in average
condition of water”, as an “outlet of commerce” (see paragraphf 73
above). In the view of the Court, Articles II and VI, taken together, pro -

vide that the right bank of a channel of the river forms the boundary onf
the assumption that this channel is a navigable “outlet of commerce”f.
Thus, Costa Rica’s rights of navigation are linked with sovereignty over
the right bank, which has clearly been attributed to Costa Rica as far as
the mouth of the river.

77. Costa Rica contends that, while no channel of the San Juan River
now flows into the Harbor Head Lagoon, there has been no significant
shifting of the bed of the main channel of the Lower San Juan River since
the Alexander Awards. Costa Rica maintains that the territory on the

right bank of that channel as far as the river’s mouth in the Caribbefan
Sea should be regarded as under Costa Rican sovereignty. According to
Costa Rica, no importance should be given to what it considers to be an
artificial caño which was excavated by Nicaragua in 2010 in order to con -
nect the San Juan River with the Harbor Head Lagoon.
78. Nicaragua argues that, as a result of natural modifications in the

geographical configuration of the disputed territory, the “first chanfnel” to
which General Alexander referred in his first Award is now a channel

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de nos jours à un chenal reliant le fleuve, en un point situé auf sud de la
lagune de Harbor Head, à l’extrémité méridionale de celle -ci. D’après le

Nicaragua, le chenal en question est le caño qu’il a dragué en 2010, à seule
fin d’en améliorer la navigabilité. Soutenant que ce caño existe depuis
nombre d’années et marque aujourd’hui la frontière, le Nicarfagua reven-
dique la souveraineté sur l’ensemble du territoire litigieux.
79. Selon le Nicaragua, des photographies aériennes et images satellite

confirment que ce caño existait avant 2010. En particulier, une image
satellite datant de 1961 en attesterait la présence à l’emplacement où les
travaux de dragage ont été réalisés en 2010.
80. Le Costa Rica souligne pour sa part le manque de clarté, surtout en
raison de la densité de la végétation, des clichés aérienfs et satellite du ter
ritoire litigieux, y compris l’image satellite de 1961. Il produit lui -même

une image satellite datée d’août 2010 qui démentirait la préfsence d’un ch-e
nal pendant l’intervalle entre l’enlèvement de la végétatfion dans la zone en
question et les opérations de dragage du caño. A l’audience, le Nicaragua
a admis que, en raison du couvert forestier, seule une reconnaissance sufr le
terrain permettrait de lever les incertitudes concernant le caño.

81. La Cour est d’avis qu’une inspection sur le terrain serait de peu
d’utilité pour reconstituer la situation antérieure à 2010. fElle considère
que, étant donné le manque de clarté que présentent, de manifère générale,
les images aériennes et satellite, conjugué au fait que les chenaufx dont
cellesci permettent de constater la présence ne correspondent pas à l’fem -

placement du caño dragué en 2010, ces éléments de preuve sont insuffisants
pour établir qu’un chenal naturel reliait le fleuve San Juan à la lagune de
Harbor Head suivant le même cours que celui du caño en question.
82. Afin de renforcer sa thèse, selon laquelle le caño existait depuis un
certain temps déjà quand il a procédé à son dragage, le Nficaragua fournit
par ailleurs trois déclarations sous serment émanant de policiers fet mili -

taires nicaraguayens, qui font référence à un cours d’eau refliant le fleuve
San Juan à la lagune, dont ils affirment qu’il était navigable penfdant une
partie de l’année. Dans les déclarations d’autres agents, ilf est fait mention
de cours d’eau coulant dans le secteur de la lagune, qui seraient navfigables
dans une certaine mesure, mais dont l’emplacement n’est pas préfcisé.

83. La Cour rappelle que, « [l]orsqu’elle apprécie la valeur probante de
toute déclaration, [elle] prend nécessairement en compte sa forme, ainsi
que les circonstances dans lesquelles elle a été reçue » ( Application de la
convention pour la prévention et la répression du crime de génocide (Croatie
c. Serbie), arrêt, C.I.J. Recueil 2015 (I), p. 78, par. 196). Les déclarations

sous serment seront considérées avec « prudence», notamment lorsqu’elles
ont été faites pour les besoins de la cause par des agents de l’fEtat ( ibid.,
p. 78, par. 196-197, faisant référence au Différend territorial et maritime
entre le Nicaragua et le Honduras dans la mer des Caraïbes (Nicaragu▯a
c. Honduras), arrêt, C.I.J. Recueil 2007 (II), p. 731, par. 244). En la pré -
sente espèce, la Cour est d’avis que les déclarations établifes par des agents

de l’Etat nicaraguayen après l’introduction de l’instance pafr le Costa Rica
ne sont que de peu de poids pour étayer la prétention du Nicaraguaf.

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5 Ord 1088.indb 76 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 701

connecting the river, at a point south of the Harbor Head Lagoon, with
the southern tip of that lagoon. The channel in question, according to

Nicaragua, is the caño that it dredged in 2010 only to improve its naviga-
bility. Relying on the alleged existence of this caño over a number of years
and contending that it now marks the boundary, Nicaragua claims sover -
eignty over the whole of the disputed territory.
79. According to Nicaragua, the existence of the caño before 2010 is

confirmed by aerial and satellite imagery. In particular, Nicaragua allefges
that a satellite picture dating from 1961 shows that a caño existed where
Nicaragua was dredging in 2010.
80. Costa Rica points out that, especially by reason of the thick vege -
tation, aerial and satellite images of the disputed territory are not clfear,
including the satellite picture of 1961. Moreover, Costa Rica produces a

satellite image dating from August 2010, which would rule out the exis -
tence of a channel in the period between the clearing of vegetation in tfhe
location of the caño and the dredging of the caño. In the oral proceedings,
Nicaragua admitted that because of the tree canopy, only an inspection
on the ground could provide certainty regarding the caño.

81. In the opinion of the Court, an inspection would hardly be useful
for reconstructing the situation prevailing before 2010. The Court consifd -
ers that, given the general lack of clarity of satellite and aerial imagfes and
the fact that the channels that may be identified on such images do not f
correspond to the location of the caño dredged in 2010, this evidence is

insufficient to prove that a natural channel linked the San Juan River
with the Harbor Head Lagoon following the same course as the caño that
was dredged.
82. In order further to substantiate the view that the caño had existed
for some time before it was dredged, Nicaragua also supplies three affifda -
vits of Nicaraguan policemen or military agents who refer to a stream

linking the San Juan River with the lagoon and assert that it was navi -
gable for part of the year. Some affidavits of other agents mention strfeams
in the area of the lagoon and describe them as navigable by boats to a
certain extent, but do not specify their location.

83. The Court recalls that “[i]n determining the evidential weight of
any statement by an individual, the Court necessarily takes into account
its form and the circumstances in which it was made” (Application of the
Convention on the Prevention and Punishment of the Crime of Genocide
(Croatia v. Serbia), Judgment, I.C.J. Reports 2015 (I), p. 78, para. 196).

Affidavits will be treated “with caution”, in particular those mafde by
State officials for purposes of litigation (ibid., pp. 78, paras. 196-197,
referring to Territorial and Maritime Dispute between Nicaragua and Hon ‑
duras in the Caribbean Sea (Nicaragua v. Honduras), Judgment,
I.C.J. Reports 2007 (II), p. 731, para. 244). In the present case, the Court
finds that the affidavits of Nicaraguan State officials, which were prfepared

after the institution of proceedings by Costa Rica, provide little support
for Nicaragua’s contention.

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84. Le Nicaragua se réfère à une carte établie en 1949 par l’finsti -
tut géographique national du Costa Rica, qui montre la présence

d’un caño à l’emplacement de celui qui a été dragué en 2010, tout en
reconnaissant que le territoire litigieux y est représenté comme rfelevant
entièrement de la souveraineté du Costa Rica. Il invoque par ailleurs une
autre carte, publiée en 1971 par le même institut, sur laquelle apparaît
une frontière proche de la ligne qu’il revendique. Cependant, la Cour

constate que ces éléments de preuve sont contredits par un certainf nombre
de cartes nicaraguayennes officielles, dont une établie en 1967 par la
direction générale de la cartographie et une autre publiée en 2003 par
l’institut nicaraguayen d’études territoriales (l’INETER, sfuivant l’acro -
nyme en espagnol), qui placent la zone litigieuse sous souveraineté f
costa-ricienne.

85. Ainsi que l’a relevé la commission de délimitation des frontièfres
en l’affaire Erythrée/Ethiopie, dans un passage que la Cour a cité, en
l’approuvant, en l’affaire relative à la Souveraineté sur Pedra Branca/
Pulau Batu Puteh, Middle Rocks et South Ledge (Malaisie/Singapour), la
carte « reste une indication de fait géographique, en particulier lorsque

l’Etat désavantagé l’a lui -même établie et distribuée, même contre ses
propres intérêts » ( arrêt, C.I.J. Recueil 2008, p. 95, par. 271). Si, en
l’espèce, les cartes publiées par les deux Etats fournissent, dans l’en -
semble, des éléments qui confortent la position du Costa Rica, leur valeur
est limitée, étant donné qu’il s’agit dans tous les cas dfe cartes à petite

échelle qui ne sont pas censées représenter de manière déftaillée le terri -
toire litigieux.
86. Les Parties invoquent toutes deux des effectivités à l’appui def leurs
revendications de souveraineté territoriale respectives. Le Costa Rica
affirme avoir exercé sa souveraineté sur le territoire litigieux fsans que cela
soulève d’opposition de la part du Nicaragua jusqu’en 2010. Il rappelle

qu’il a adopté des lois s’appliquant spécifiquement à la fzone en question
et octroyé des autorisations et des droits de jouissance visant ce mêfme
territoire, et qu’IslaPortillos était comprise dans la région qu’il a fait ins-
crire sur la liste des zones humides d’importance internationale au tfitre de
la convention de Ramsar (Humedal Caribe Noreste). Il fait en outre

remarquer que, lorsque le Nicaragua a demandé l’inscription de sa propre
zone humide d’importance internationale dans ce même secteur (Refugio
de Vida Silvestre Río San Juan), celle-ci n’englobait que la lagune de Har -
bor Head, à l’exclusion du territoire litigieux.
87. Le Nicaragua soutient pour sa part s’être comporté en souverainf à

l’égard du territoire litigieux. Invoquant des déclarations soufs serment de
ses agents et deux rapports de police, il affirme que, au moins depuis fla fin
des années 1970, ses forces armées, navales et policières ont toutes
patrouillé dans la lagune de Harbor Head et aux alentours, y compris les
caños qui relient celle-ci au fleuve San Juan.
88. Le Costa Rica met en doute la valeur des éléments de preuve pro -

duits par le Nicaragua à l’appui de sa prétention, selon laquelfle il aurait
exercé des pouvoirs souverains dans le territoire litigieux.

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84. Nicaragua refers to a map produced in 1949 by the National Geo -
graphic Institute of Costa Rica which shows a caño in the location of the

one dredged in 2010. It acknowledges, however, that the map in question f
describes the entire disputed territory as being under Costa Rican sover-
eignty. Nicaragua further invokes a map published in 1971 by the same
Institute which shows a boundary close to the line claimed by Nicaragua.f
However, the Court notes that this evidence is contradicted by several

official maps of Nicaragua, in particular a map of 1967 of the Directorfate
of Cartography and a map, dating from 2003, published by the Nicara -
guan Institute of Territorial Studies (INETER, by its Spanish acronym)f,
which depict the disputed area as being under Costa Rica’s sovereignty.

85. As the Boundary Commission in the Eritrea/Ethiopia case stated,
in a passage that was quoted with approval by the Court in the case con -
cerning Sovereignty over Pedra Branca/Pulau Batu Puteh, Middle Rocks
and South Ledge (Malaysia/Singapore) , a map “stands as a statement of
geographical fact, especially when the State adversely affected has itself

produced and disseminated it, even against its own interest” (Judgment,
I.C.J. Reports 2008, p. 95, para. 271). In the present case, the evidence of
maps published by the Parties on the whole gives support to Costa Rica’s
position, but their significance is limited, given that they are all smafllle
maps which are not focused on the details of the disputed territory.

86. Both Parties invoke effectivités to corroborate their claims to ter -
ritorial sovereignty. Costa Rica argues that it had exercised sovereignty
over the disputed territory without being challenged by Nicaragua until f
2010. Costa Rica recalls that it adopted legislation applying specifically to

that area, that it issued permits or titles to use land in the same terrfitory,
and that Isla Portillos was included within the area it designated as a
wetland of international importance under the Ramsar Convention
(Humedal Caribe Noreste). Costa Rica notes that, when Nicaragua regis -
tered its own wetland of international importance concerning the area

(Refugio de Vida Silvestre Río San Juan), it only included the Harbor
Head Lagoon and did not encompass the disputed territory.

87. Nicaragua for its part contends that it acted as sovereign over the

disputed territory. Relying on affidavits by State officials and two pfolice
reports, it asserts that at least since the late 1970s the Nicaraguan arfmy,
navy and police have all patrolled the area in and around Harbor Head
Lagoon, including the caños connecting the lagoon with the San Juan
River.
88. Costa Rica questions the value of the evidence adduced by Nicara -

gua to substantiate its claim of having exercised sovereign powers in the
disputed territory.

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Selon le Nicaragua, la souveraineté que le Costa Rica prétend avoir
exercée sur le territoire litigieux n’existait que « sur le papier » et n’est

étayée par aucune action concrète sur les lieux.
89. Les effectivités invoquées par les Parties, dont la Cour constate
qu’elles sont en tout état de cause d’une portée limitée,f ne sauraient affec-
ter le titre de souveraineté découlant du traité de 1858 et des sentences
rendues par le président Cleveland et le général Alexander.

90. La Cour relève que l’existence de longue date d’un caño navigable à
l’emplacement revendiqué par le Nicaragua est mise en doute par laf pré -
sence, dans le lit de ce cours d’eau, d’arbres de grande taille etf d’un grand
âge qui ont été enlevés par le Nicaragua en 2010. Par ailleurs, ainsi que l’a
fait observer l’expert principal du Costa Rica, s’il s’était agi d’un défluent
du fleuve San Juan, «les sédiments auraient rempli, du moins en partie, la

portion méridionale de la lagune ».De plus, étant donné que, dès le milieu
de l’été 2011, le caño dragué en 2010 ne reliait plus le fleuve à la lagune, ce
dont conviennent les experts des deux Parties, il paraît improbable qfu’un
chenal navigable suivant le même cours ait pu exister pendant nombre
d’années avant que le Nicaragua effectue ses opérations de dragfage. Ce

caño pourrait difficilement avoir été le chenal navigable offrant un fdébou -
ché en mer pour le commerce, mentionné ci-dessus (voir le paragraphe76).
91. Retenir la position du Nicaragua reviendrait à priver le Costa Rica
de sa souveraineté territoriale sur la rive droite du fleuve San Juan jusqu’à
son embouchure, en violation des prescriptions du traité de 1858 et de la

sentence Cleveland. Par ailleurs, selon l’article VI du traité de 1858 (cité
ci-dessous au paragraphe 133), les droits de navigation conférés au
Costa Rica visent les eaux du fleuve, dont la rive droite constitue la fron -
tière entre les deux pays. Comme la Cour l’a fait observer (voir fle para -
graphe 76 ci-dessus), ces droits de navigation et la souveraineté sur la rive
droite sont liés.

92. La Cour conclut dès lors que la rive droite du caño que le Nicara-
gua a dragué en 2010 ne correspond pas à la frontière entre les deux Etats
et que le territoire relevant de la souveraineté du Costa Rica s’étend à la
rive droite du cours inférieur du San Juan jusqu’à l’embouchure de
celui-ci dans la mer des Caraïbes. La souveraineté sur le territoire litfigieux

appartient donc au Costa Rica.
93. Il n’est pas contesté que, depuis 2010, le Nicaragua a mené un fcer -
tain nombre d’activités sur le territoire litigieux, y procédanft notamment
au creusement de trois caños et à l’établissement d’une présence militaire
par endroits. Ces activités constituaient des violations de la souveraineté

territoriale du Costa Rica. Le Nicaragua est responsable de ces violations
et est, en conséquence, tenu de réparer les dommages causés parf ses acti -
vités illicites (voir section E).
94. Selon le Costa Rica, « en occupant et en revendiquant une partie
du territoire costa-ricien», le Nicaragua a manqué à d’autres obligations
lui incombant.

95. Au point 2 b) iv)de ses conclusions finales, le Costaica prie la Cour
de dire et juger que le Nicaragua a manqué à l’obligation qu’fil avait «de ne

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5 Ord 1088.indb 80 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 703

Nicaragua argues that Costa Rica’s claimed exercise of sovereignty was
merely a limited “paper presence” in the disputed territory not sufpported

by any actual conduct on the ground.
89. The effectivités invoked by the Parties, which the Court considers
are in any event of limited significance, cannot affect the title to sover -
eignty resulting from the 1858 Treaty and the Cleveland and Alexander
Awards.

90. The Court notes that the existence over a significant span of time
of a navigable caño in the location claimed by Nicaragua is put into ques-
tion by the fact that in the bed of the channel there were trees of consfide-
able size and age which had been cleared by Nicaragua in 2010. Moreover,f
as was noted by Costa Rica’s main expert, if the channel had been a dis -
tributary of the San Juan River, “sediment would have filled in, or aft a

minimum partially -filled, the southern part of the lagoon”. Furthermore,
the fact that, as the Parties’ experts agree, the caño dredged in 2010 no
longer connected the river with the lagoon by mid -summer 2011 casts
doubt on the existence over a number of years of a navigable channel folf -
lowing the same course before Nicaragua carried out its dredging activi -

ties. This caño could hardly have been the navigable outlet of commerce
referred to above (see paragraph 76).
91. If Nicaragua’s claim were accepted, Costa Rica would be prevented
from enjoying territorial sovereignty over the right bank of the San Juafn
River as far as its mouth, contrary to what is stated in the 1858 Treaty

and in the Cleveland Award. Moreover, according to Article VI of the
1858 Treaty (quoted below at paragraph 133), Costa Rica’s rights of nav -
igation are over the waters of the river, the right bank of which forms the
boundary between the two countries. As the Court noted (see para -
graph 76 above), these rights of navigation are linked with sovereignty
over the right bank.

92. The Court therefore concludes that the right bank of the caño
which Nicaragua dredged in 2010 is not part of the boundary between
Costa Rica and Nicaragua, and that the territory under Costa Rica’s sov-
ereignty extends to the right bank of the Lower San Juan River as far asf
its mouth in the Caribbean Sea. Sovereignty over the disputed territory f

thus belongs to Costa Rica.
93. It is not contested that Nicaragua carried out various activities in
the disputed territory since 2010, including excavating three caños and
establishing a military presence in parts of that territory. These activfities
were in breach of Costa Rica’s territorial sovereignty. Nicaragua is

responsible for these breaches and consequently incurs the obligation tof
make reparation for the damage caused by its unlawful activities (see Sec -
tion E).
94. Costa Rica submits that “by occupying and claiming Costa Rican
territory” Nicaragua also committed other breaches of its obligationsf.

95. Costa Rica’s final submission 2 (b) (iv) asks the Court to adjudge
and declare that Nicaragua breached its obligation “not to use the Safn

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pas utiliser le fleuve San Juan pour perpétrer des actes d’hostilité » aux
termes de l’articleIX du traité de 1858. Cette disposition est ainsi rédigée:

«En aucun cas, pas même si elles devaient malheureusement se
trouver en état de guerre, les Républiques du Costa Rica et du Nica-

ragua ne seront autorisées à se livrer à de quelconques actes df’hosti-
lité l’une envers l’autre, que ce soit dans le port de San Juan del
Norte, sur le fleuve San Juan ou sur le lac de Nicaragua. » [Version
originale en espagnol : « Por ningún motivo, ni en caso y estado de
guerra, en que por desgracia llegasen á encontrarse las Repúblicas▯ de

Nicaragua y Costa Rica, les será permitido ejercer ningún acto de hos ‑
tilidad entre ellas en el puerto de San Juan del Norte, ni en el río de
este nombre y Lago de Nicaragua. ] »

Il n’a été produit aucun élément de preuve montrant que lfe fleuve
San Juan avait été le théâtre d’hostilités. Il y a donc lifeu de rejeter la pré-
tention reposant sur le manquement, par le Nicaragua, aux obligations
lui incombant au titre de l’article IX du traité.
96. Au point 2 b) ii) de ses conclusions finales, le Costa Rica invite la

Cour à conclure à la violation par le Nicaragua de « l’interdiction de la
menace ou de l’emploi de la force consacrée par la Charte des Natifons
Unies au paragraphe 4 de son article 2 et par la Charte de l’Organisation
des Etats américains en son article 22 ».
97. Les agissements du Nicaragua pertinents à cet égard ont été fabor -

dés dans le cadre de l’examen de la violation de la souverainetéf territo -
riale du Costa Rica. Le fait que le Nicaragua ait considéré que les activités
auxquelles il se livrait avaient lieu sur son propre territoire n’empfêche pas
que celles-ci puissent être considérées comme relevant de l’emploi illifcite
de la force, ce qui soulèverait la question de leur conformité àf la Charte
des Nations Unies et à la Charte de l’Organisation des Etats américains.

Dans les circonstances de l’espèce, toutefois, puisque le caractèfre illicite
de ces activités a déjà été établi, la Cour n’a pasf à s’attarder plus longue -
ment sur ce chef de conclusions du Costa Rica. Tout comme en l’affaire
de la Frontière terrestre et maritime entre le Cameroun et le Nigéria
(Cameroun c. Nigéria ; Guinée équatoriale (intervenant)) , la Cour estime

que, «du fait même du présent arrêt et de l’évacuation » du territoire liti-
gieux, le préjudice subi par le Costa Rica «aura en tout état de cause été
suffisamment pris en compte » (arrêt, C.I.J. Recueil 2002, p.452, par. 319).
98. Au point 2 b) iii) de ses conclusions finales, le Costa Rica prie la
Cour de déclarer que le Nicaragua a soumis le territoire costa -ricien, fût-ce

de manière temporaire, à une occupation militaire, en contraventiofn de
l’article 21 de la Charte de l’Organisation des Etats américains ». La pre -
mière phrase de cette disposition est ainsi libellée: «Le territoire d’un Etat
est inviolable, il ne peut être l’objet d’occupation militaire fni d’autres
mesures de force de la part d’un autre Etat, directement ou indirectefment,
pour quelque motif que ce soit et même de manière temporaire.»

Pour étayer cette demande, le Costa Rica se réfère à la préfsence de
personnel militaire du Nicaragua dans le territoire litigieux.

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5 Ord 1088.indb 82 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 704

Juan River to carry out hostile acts” under Article IX of the 1858 Treaty.
This provision reads as follows :

“Under no circumstances, and even in [the] case that the Republics
of Costa Rica and Nicaragua should unhappily find themselves in a

state of war, neither of them shall be allowed to commit any act of
hostility against the other, whether in the port of San Juan del Norte,
or in the San Juan River, or the Lake of Nicaragua.” [In the Spanish f
original: “Por ningún motivo, ni en caso y estado de guerra, en que por
desgracia llegasen á encontrarse las Repúblicas de Nicaragua y

Costa Rica, les será permitido ejercer ningún acto de hostilidad entre
ellas en el puerto de San Juan del Norte, ni en el río de este nombre▯ y
Lago de Nicaragua.”]

No evidence of hostilities in the San Juan River has been provided. Therfe -
fore the submission concerning the breach of Nicaragua’s obligations f
under Article IX of the Treaty must be rejected.

96. In its final submission 2 (b) (ii), Costa Rica asks the Court to find

a breach by Nicaragua of “the prohibition of the threat or use of forfce
under Article 2 (4) of the Charter of the United Nations and Article 22 of
the Charter of the Organization of American States”.

97. The relevant conduct of Nicaragua has already been addressed in

the context of the Court’s examination of the violation of Costa Rica’s
territorial sovereignty. The fact that Nicaragua considered that its actfivi-
ties were taking place on its own territory does not exclude the possibiflity
of characterizing them as an unlawful use of force. This raises the issufe of
their compatibility with both the United Nations Charter and the Charterf
of the Organization of American States. However, in the circumstances,

given that the unlawful character of these activities has already been
established, the Court need not dwell any further on this submission. Asf
in the case concerning Land and Maritime Boundary between Cameroon
and Nigeria (Cameroon v. Nigeria : Equatorial Guinea intervening) , the
Court finds that, “by the very fact of the present Judgment and of thfe

evacuation” of the disputed territory, the injury suffered by Costa Rica
“will in all events have been sufficiently addressed” (Judgment,
I.C.J. Reports 2002, p. 452, para. 319).
98. In its final submission 2 (b) (iii), Costa Rica requests the Court to
find that Nicaragua made the territory of Costa Rica “the object, even

temporarily, of military occupation, contrary to Article 21 of the Charter
of the Organization of American States”. The first sentence of this pfrovi -
sion stipulates: “The territory of a State is inviolable ; it may not be the
object, even temporarily, of military occupation or of other measures off
force taken by another State, directly or indirectly, on any grounds whaft-
ever.”

In order to substantiate this claim, Costa Rica refers to the presence of
military personnel of Nicaragua in the disputed territory.

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5 Ord 1088.indb 83 19/10/16 12:01 705 certaines activitésf et construction d’unfe route (arrêt)

99. La Cour a déjà établi que la présence de personnel militairef du

Nicaragua dans le territoire litigieux constitue un fait illicite en tanft que
violation de la souveraineté territoriale du Costa Rica. Il n’est fpas néces-
saire pour la Cour de déterminer si cette conduite du Nicaragua repréf -
sente une occupation militaire en contravention de l’article 21 de la Charte
de l’Organisation des Etats américains.

B. Allégations de violation du droit international de l’environnement▯

100. La Cour abordera à présent les allégations du Costa Rica concer-
nant la violation par le Nicaragua des obligations que lui impose le drofit

international de l’environnement s’agissant des activités de drfagage entre-
prises par ce dernier en vue d’améliorer la navigabilité du coufrs inférieur
du fleuve San Juan. Ces allégations concernant l’environnement peuvent
être regroupées dans deux grandes catégories. En premier lieu, fselon le
Costa Rica, le Nicaragua a contrevenu à des obligations de nature procé -

durale, soit celle de procéder à une évaluation appropriée de l’impact
transfrontière sur l’environnement de ses opérations de dragage, ainsi que
celle de l’informer et de le consulter au sujet de ces opérations.f En second
lieu, le Costa Rica soutient que le Nicaragua a manqué à l’obligation de

fond qui lui incombait, en matière de protection de l’environnemenft, de
ne pas causer de dommage au territoire costa -ricien. La Cour examinera
successivement ces allégations du Costa Rica.

1. Obligations de nature procédurale

a) Allégation de violation de l’obligation d’effectuer une éval▯uation de
l’impact sur l’environnement

101. De façon générale, les Parties s’accordent à reconnaître l’existence
en droit international général d’une obligation de procéder à une évalua -
tion de l’impact sur l’environnement concernant les activités efxercées

dans le ressort d’un Etat qui risquent de causer des dommages importafnts
à d’autres Etats, en particulier dans les zones ou régions préfsentant des
conditions environnementales partagées.
102. Le Costa Rica avance que le Nicaragua ne s’est pas acquitté de

cette obligation et qu’il doit le faire avant d’entreprendre toutef opération
de dragage à l’avenir. Il avance en particulier que l’analyse efffectuée dans
le cadre de l’étude de l’impact sur l’environnement qu’a fmenée le Nicara -
gua en 2006 n’étayait pas la conclusion selon laquelle le projet dfe dragage
n’aurait aucune incidence sur le débit du fleuve Colorado, et que cette

étude ne comportait par ailleurs aucune évaluation de l’impact fdu projet
sur les zones humides. Or les modifications artificielles de la morpholofgie
du fleuve entraînées par les activités de dragage du Nicaragufa étaient,
selon lui, susceptibles de porter préjudice à ces zones humides. Ifl ajoute
que le rapport de la mission consultative Ramsar n o 72, datant d’avril2011,

a confirmé l’existence d’un risque de dommage transfrontière et montré

44

5 Ord 1088.indb 84 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 705

99. The Court has already established that the presence of military per-
sonnel of Nicaragua in the disputed territory was unlawful because it vifo-

lated Costa Rica’s territorial sovereignty. The Court does not need to
ascertain whether this conduct of Nicaragua constitutes a military occu -
pation in breach of Article 21 of the Charter of the Organization of
American States.

B. Alleged Violations of International Environmental Law

100. The Court will now turn to Costa Rica’s allegations concerning
violations by Nicaragua of its obligations under international environ -
mental law in connection with its dredging activities to improve the navfi-
gability of the Lower San Juan River. Costa Rica’s environmental claims

can be grouped into two broad categories. First, according to Costa Rica,
Nicaragua breached the procedural obligations to carry out an appropri -
ate transboundary environmental impact assessment of its dredging
works, and to notify, and consult with, Costa Rica regarding those works.
Secondly, Costa Rica alleges that Nicaragua breached the substantive

environmental obligation not to cause harm to Costa Rica’s territory.
The Court will consider Costa Rica’s allegations in turn.

1. Procedural obligations

(a) The alleged breach of the obligation to carry out an environmental
impact assessment

101. The Parties broadly agree on the existence in general international

law of an obligation to conduct an environmental impact assessment con-
cerning activities carried out within a State’s jurisdiction that risfk causing
significant harm to other States, particularly in areas or regions of shfared
environmental conditions.

102. Costa Rica claims that Nicaragua has not complied with that
obligation, and must do so in advance of any further dredging. It submitfs
in particular that the analysis carried out in the Environmental Impact f
Study undertaken by Nicaragua in 2006 does not support the conclusion
that the dredging project would cause no harm to the flow of the Colo -

rado River. Moreover, according to Costa Rica, the Environmental
Impact Study did not assess the impact of the dredging programme on
the wetlands. Costa Rica maintains that the artificial changes to the mor -
phology of the river resulting from Nicaragua’s dredging activities rfisked
causing an adverse impact on those wetlands. Costa Rica also argues that

a document entitled “Report : Ramsar Advisory Mission No. 72”, pre-
pared in April 2011, confirms the existence of a risk of transboundary

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5 Ord 1088.indb 85 19/10/16 12:01 706 certaines activitésf et construction d’unfe route (arrêt)

que l’étude réalisée par le Nicaragua ne comportait aucune afnalyse de ce

risque, pour ensuite conclure qu’une telle analyse aurait dû êtfre entreprise
avant la mise en œuvre du programme de dragage.
103. Le Nicaragua soutient pour sa part que l’étude de l’impact sur l’en-
vironnement qu’il a effectuée en 2006 et les documents y afférefnts compo-r
taient une analyse exhaustive de l’effet transfrontière potentiel fde son

programme de dragage, y compris ses conséquences sur l’environnemefnt du
Costa Rica et la réduction éventuelle du débit du fleuve Colorado. Il sou-
ligne que cette étude a abouti à la conclusion que le programme nef comp-or
tait aucun risque de dommage transfrontière important et aurait mêfme un
effet bénéfique pour le fleuve San Juan et la zone environnante. Quant au
o
rapport de la mission consultative Ramsar n 72, il fait valoir qu’il ne
s’agissait que d’une version préliminaire, sur laquelle il a cofmmuniqué ses
observations en temps voulu, mais qui n’a jamais été finaliséfe par le Secr-é
tariat de la convention de Ramsar et qui ne devrait en conséquence sef voir
accorder aucun poids. Il soutient en outre que la conclusion énoncéfe dans

ce rapport, selon laquelle il n’avait été effectué aucune anfalyse de l’impact
du programme de dragage sur l’hydrologie de la zone, était erronéfe, comme
il l’a souligné dans les observations qu’il a transmises au Secfrétariat.

*

104. La Cour a eu l’occasion, dans l’arrêt qu’elle a rendu en l’faffaire
relative à des Usines de pâte à papier sur le fleuve Uruguay (Argentine
c. Uruguay), de souligner ce qui suit :

«[L]e principe de prévention, en tant que règle coutumière, troufve
son origine dans la diligence requise (« due diligence ») de l’Etat sur
son territoire. Il s’agit de « l’obligation, pour tout Etat, de ne pas

laisser utiliser son territoire aux fins d’actes contraires aux droitfs
d’autres Etats » ( Détroit de Corfou (Royaume‑Uni c. Albanie), fond,
arrêt, C.I.J. Recueil 1949, p. 22). En effet, l’Etat est tenu de mettre en
œuvre tous les moyens à sa disposition pour éviter que les actifvités
qui se déroulent sur son territoire, ou sur tout espace relevant de sfa

juridiction, ne causent un préjudice sensible à l’environnementf d’un
autre Etat. » (Arrêt, C.I.J. Recueil 2010 (I), p. 55-56, par. 101.)

Elle a en outre conclu que « l’on peut désormais considérer qu’il existe, en
droit international général, une obligation de procéder à unfe évaluation
de l’impact sur l’environnement lorsque l’activité industrieflle projetée
risque d’avoir un impact préjudiciable important dans un cadre trafns -
frontière, et en particulier sur une ressource partagée » ( ibid., p. 83,

par. 204). Même si la conclusion formulée par la Cour en l’affaire frelative
à des Usines de pâte à papier visait des activités industrielles, le principe
sous -jacent vaut, de manière générale, pour toute activité projetfée suscep -
tible d’avoir un impact préjudiciable important dans un cadre tranfsfron-
tière. En conséquence, afin de s’acquitter de l’obligation qfui lui incombe

de faire preuve de la diligence requise en vue de prévenir les dommagfes

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5 Ord 1088.indb 86 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 706

harm, shows that Nicaragua’s study did not contain an assessment of that
risk, and concludes that such an assessment should have been undertaken f

prior to the implementation of the dredging programme.
103. Nicaragua contends for its part that its 2006 Environmental
Impact Study and the related documentation fully addressed the potentialf
transboundary impact of its dredging programme, including its effects onf
the environment of Costa Rica and the possible reduction in flow of the

Colorado River. It points out that this study concluded that the pro -
gramme posed no risk of significant transboundary harm and would actu-
ally have beneficial effects for the San Juan River and the surrounding
area. As to the document entitled “Report : Ramsar Advisory Mission
No. 72”, Nicaragua argues that it was only a draft report, on which Nica-
ragua commented in a timely manner, but which the Ramsar Secretariat

never finalized ; accordingly, it should be given no weight. Furthermore,
Nicaragua explains that the report’s conclusion that there had been nfo
analysis of the impact of the dredging programme on the hydrology of
the area was incorrect, as Nicaragua pointed out in the comments it sub -
mitted to the Ramsar Secretariat.

*

104. As the Court has had occasion to emphasize in its Judgment in

the case concerning Pulp Mills on the River Uruguay (Argentina v. Uru‑
guay) :
“the principle of prevention, as a customary rule, has its origins inf the

due diligence that is required of a State in its territory. It is ‘every
State’s obligation not to allow knowingly its territory to be used fofr
acts contrary to the rights of other States’ (Corfu Channel (United
Kingdom v. Albania), Merits, Judgment, I.C.J. Reports 1949, p. 22).
A State is thus obliged to use all the means at its disposal in order tof

avoid activities which take place in its territory, or in any area underf
its jurisdiction, causing significant damage to the environment of
another State.” (Judgment, I.C.J. Reports 2010 (I), pp. 55-56,
para. 101.)

Furthermore, the Court concluded in that case that“it may now be consid -
ered a requirement under general international law to undertake an envir -
onmental impact assessment where there is a risk that the proposed

industrial activity may have a significant adverse impact in a transbound-
ary context, in particular, on a shared resource” (ibid., p. 83, para. 204).
Although the Court’s statement in the Pulp Mills case refers to industrial
activities, the underlying principle applies generally to proposed activfities
which may have a significant adverse impact in a transboundary context. f
Thus, to fulfil its obligation to exercise due diligence in preventing signifi-

cant transboundary environmental harm, a State must, before embarking
on an activity having the potential adversely to affect the environment of

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5 Ord 1088.indb 87 19/10/16 12:01 707 certaines activitésf et construction d’unfe route (arrêt)

environnementaux transfrontières importants, un Etat doit, avant d’fen -
treprendre une activité pouvant avoir un impact préjudiciable sur fl’envi -

ronnement d’un autre Etat, vérifier s’il existe un risque de dommage
transfrontière important, ce qui déclencherait l’obligation de fréaliser une
évaluation de l’impact sur l’environnement.
C’est à la lumière des circonstances propres à chaque cas qufe doit être
déterminée la teneur de l’évaluation de l’impact sur l’fenvironnement.
Ainsi que la Cour l’a dit en l’affaire relative à des Usines de pâte à papier,

«il revient à chaque Etat de déterminer, dans le cadre de sa légfisla -
tion nationale ou du processus d’autorisation du projet, la teneur

exacte de l’évaluation de l’impact sur l’environnement requifse dans
chaque cas en prenant en compte la nature et l’ampleur du projet en
cause et son impact négatif probable sur l’environnement, ainsi qufe
la nécessité d’exercer, lorsqu’il procède à une telle févaluation, toute
la diligence requise » (.I.J. Recueil 2010 (I), p. 83, par. 205).

Si l’évaluation de l’impact sur l’environnement confirme l’fexistence d’un
risque de dommage transfrontière important, l’Etat d’origine esft tenu,
conformément à son obligation de diligence due, d’informer et de consul -

ter de bonne foi l’Etat susceptible d’être affecté, lorsque fcela est nécessaire
aux fins de définir les mesures propres à prévenir ou réduirfe ce risque.
105. La Cour relève que, s’agissant des zones humides, le risque allégué
par le CostaRica se rapporte à l’ensemble des activités de dragage du Nica -
ragua, y compris celles relatives au caño de2010. Elle rappelle que les activ-i
tés de dragage entreprises en violation de la souveraineté territoriale du

CostaRica ont déjà été examinées. Elle se bornera donc à refchercher si celles
qui ont été menées par le Nicaragua dans le cours inférieur fdu fleuveJ Suann
comportaient un risque de dommage transfrontière important. Le risquef
principal évoqué par le Costa Rica tenait à l’impact préjudiciable éventuel de
ces activités de dragage sur le débit du fleuve Colorado, lesqueflles auraient
également pu porter préjudice à sa zone humide. En 2006, le Nicfaragua a

procédé à une étude de l’impact que le projet de dragage faurait sur son
propre environnement, laquelle a également indiqué que le programmfe n’au -
rait pas d’effet sensible sur le débit du fleuve Colorado, conclfusion que les
experts de l’une et l’autre des Parties ont ultérieurement confifrmée. Après
examen des éléments de preuve versés au dossier, y compris les frapports et
exposés des experts que les deux Parties ont fait entendre, la Cour cfonclut

que le programme de dragage envisagé en 2006 n’était pas de natfure à créer
un risque de dommage transfrontière important, que ce soit à l’égard du
débit du fleuve Colorado ou de la zone humide du Costa Rica. En l’absence
de risque de dommage transfrontière important, le Nicaragua n’avaift pas
l’obligation d’effectuer une évaluation de l’impact sur l’fenvironnement.

b) Allégation de violation d’une obligation de notification et de

consultation

106. Les Parties s’accordent à admettre l’existence, en droit internatio -
nal général, d’une obligation de notification et de consultatiofn envers

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5 Ord 1088.indb 88 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 707

another State, ascertain if there is a risk of significant transboundaryf

harm, which would trigger the requirement to carry out an environmental f
impact assessment.

Determination of the content of the environmental impact assessment

should be made in light of the specific circumstances of each case. As tfhe
Court held in the Pulp Mills case :

“it is for each State to determine in its domestic legislation or in fthe
authorization process for the project, the specific content of the envir-f
onmental impact assessment required in each case, having regard to
the nature and magnitude of the proposed development and its likely
adverse impact on the environment as well as to the need to exercise

due diligence in conducting such an assessment” ( I.C.J. Reports
2010 (I), p. 83, para. 205).

If the environmental impact assessment confirms that there is a risk of fsig -
nificant transboundary harm, the State planning to undertake the activitfy
is required, in conformity with its due diligence obligation, to notify fand
consult in good faith with the potentially affected State, where that isf nece-
sary to determine the appropriate measures to prevent or mitigate that rfisk.
105. The Court notes that the risk to the wetlands alleged by CostaRica

refers to Nicaragua’s dredging activities as a whole, including the dfredg -
ing of the 2010 caño. The Court recalls that the dredging activities carried
out in breach of Costa Rica’s territorial sovereignty have been considered
previously. Accordingly, the Court will confine its analysis to ascertaining
whether Nicaragua’s dredging activities in the Lower San Juan carriedf a

risk of significant transboundary harm. The principal risk cited by
Costa Rica was the potential adverse impact of those dredging activities
on the flow of the Colorado River, which could also adversely affect
Costa Rica’s wetland. In 2006, Nicaragua conducted a study of the impact
that the dredging programme would have on its own environment, which
also stated that the programme would not have a significant impact on

the flow of the Colorado River. This conclusion was later confirmed byf
both Parties’ experts. Having examined the evidence in the case file,f
including the reports submitted and testimony given by experts called byf
both Parties, the Court finds that the dredging programme planned in
2006 was not such as to give rise to a risk of significant transboundaryf
harm, either with respect to the flow of the Colorado River or to

Costa Rica’s wetland. In light of the absence of risk of significant trans -
boundary harm, Nicaragua was not required to carry out an environmen-
tal impact assessment.

(b) The alleged breach of an obligation to notify and consult

106. The Parties concur on the existence in general international law of

an obligation to notify, and consult with, the potentially affected Statfe in

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l’Etat susceptible d’être touché pour ce qui concerne les acftivités posant
un risque de dommage transfrontière important. Le Costa Rica soutient

que, indépendamment des obligations que lui impose le droit internatifo -
nal général, le Nicaragua était tenu de l’informer et de le fconsulter au titre
de traités auxquels ils sont tous deux parties. En premier lieu, il affirme
que le paragraphe 2 de l’article 3 et l’article 5 de la convention de Ramsar
énoncent une telle obligation. En second lieu, il soutient que l’aflinéag) de

l’article 13 et l’article 33 de la convention concernant la conservation de
la biodiversité et la protection des zones prioritaires de faune et dfe flore
sauvages d’Amérique centrale établissent l’obligation d’éfchanger l’infor -
mation relative aux activités susceptibles de porter une atteinte parfticu-
lière à des ressources biologiques.
107. Bien qu’il ne conteste pas l’existence d’une obligation de notiffica-

tion et de consultation en droit international général, le Nicaragfua affirme
que, en l’espèce, la portée de cette obligation est limitée fpar le traité de
1858, selon l’interprétation qu’en a donnée la sentence Cleveland, en tant
que lex specialis pour ce qui est des obligations d’ordre procédural. D’aprèsf
lui, puisque ce texte n’énonce aucune obligation de notification ofu de

consultation en ce qui concerne le dragage et autres « travaux d’améliora -
tion», les faits de l’espèce échappent à l’application de ftoute obligation de
cette nature que prévoirait le droit coutumier ou conventionnel. En tfout
état de cause, il soutient que, les études menées par les deux fpays ayant
montré que son programme de dragage n’entraînerait vraisemblablfement

aucun dommage transfrontière important, aucune obligation de notifica -
tion et de consultation ne serait entrée en jeu. Il ajoute que ni le fpara -
graphe 2 de l’article 3 ni l’article 5 de la convention de Ramsar ne trouve
à s’appliquer en l’espèce. S’agissant de la convention cofncernant la conse-r
vation de la biodiversité et la protection des zones prioritaires de ffaune et
de flore sauvages d’Amérique centrale, elle n’énonce selonf lui aucune obl-i

gation en matière d’échange d’information concernant les actfivités suscep -
tibles de porter une atteinte particulière aux ressources biologiquesf ; tout
au plus encourage-t-elle les Etats dans ce sens.

*

108. La Cour observe que le fait que le traité de 1858 énonce, en
matière de notification et de consultation, des obligations limitées visant
certaines situations précises n’a pas pour effet d’écarter df’autres obliga -
tions de nature procédurale relatives aux dommages transfrontières, qui

pourraient exister en droit international conventionnel ou coutumier. Enf
tout état de cause, la Cour estime que, puisque le droit internationafl n’im -
posait au Nicaragua aucune obligation d’effectuer une évaluation dfe l’im-
pact sur l’environnement en l’absence de risque de dommage transfrfontière
important (voir le paragraphe 105 ci-dessus), il n’était pas tenu d’infor -
mer ou de consulter le Costa Rica.

109. Quant à la prétendue existence d’une obligation de notificationf et
de consultation qui s’imposerait au titre de certains traités, la Cour

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5 Ord 1088.indb 90 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 708

respect of activities which carry a risk of significant transboundary hafrm.
Costa Rica contends that, in addition to its obligations under general

international law, Nicaragua was under a duty to notify and consult with
it as a result of treaty obligations binding on the Parties. First, it afsserts
that Article 3, paragraph 2, and Article 5 of the Ramsar Convention pro-
vide for a duty to notify and consult. Secondly, it submits that Arti -
cles 13 (g) and 33 of the Convention for the Conservation of the

Biodiversity and Protection of Priority Wilderness Areas in Central
America establish an obligation to share information related to activitifes
which may be particularly damaging to biological resources.

107. While not contesting the existence of an obligation to notify and

consult under general international law, Nicaragua asserts that in the
present case such obligation is limited by the 1858 Treaty, as interpreted
by the Cleveland Award, which constitutes the lex specialis with respect
to procedural obligations. For Nicaragua, since the 1858 Treaty contains
no duty to notify or consult with respect to dredging or any other “wforks

of improvement”, any such duty in customary or treaty law does not
apply to the facts of the case. In any event, Nicaragua asserts that a dfuty
to notify and consult would not be triggered because both countries’ f
studies have shown that Nicaragua’s dredging programme posed no like -
lihood of significant transboundary harm. Nicaragua further argues that f

neither Article 3, paragraph 2, nor Article 5 of the Ramsar Convention is
applicable to the facts of the case. With respect to the Convention for fthe
Conservation of the Biodiversity and Protection of Priority Wilderness
Areas in Central America, Nicaragua asserts that it does not set out an f
obligation to share information relating to activities which may be par -
ticularly damaging to biological resources; at most it encourages States to

do so.

*

108. The Court observes that the fact that the 1858 Treaty may con -
tain limited obligations concerning notification or consultation in specfific
situations does not exclude any other procedural obligations with regardf
to transboundary harm which may exist in treaty or customary interna -

tional law. In any event, the Court finds that, since Nicaragua was not f
under an international obligation to carry out an environmental impact
assessment in light of the absence of risk of significant transboundary
harm (see paragraph 105 above), it was not required to notify, or consult
with, Costa Rica.

109. As to the alleged existence of an obligation to notify and consult
in treaties binding on the Parties, the Court observes that both CostaRica

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observe que le Costa Rica et le Nicaragua sont tous deux parties à la
convention de Ramsar et à la convention concernant la conservation def

la biodiversité et la protection des zones prioritaires de faune et dfe flore
sauvages d’Amérique centrale. Elle rappelle que le paragraphe 2 de l’ar-
ticle3 de la convention de Ramsar dispose :

«Chaque Partie contractante prend les dispositions nécessaires
pour être informée dès que possible des modifications des caracftéris-
tiques écologiques des zones humides situées sur son territoire etf ins-
crites sur la Liste [des zones humides d’importance internationale], f

qui se sont produites, ou sont en train ou susceptibles de se produire, f
par suite d’évolutions technologiques, de pollution ou d’une auftre
intervention humaine. Les informations sur de telles modifications
seront transmises sans délai [au Secrétariat de la convention de
Ramsar].»

Bien que ce paragraphe énonce une obligation de notification, celle -ci se
résume à informer le Secrétariat de la convention de Ramsar au fsujet des
modifications touchant ou susceptibles de toucher les « caractéristiques

écologiques des zones humides » situées sur le territoire de l’Etat en ques-
tion. En l’espèce, les éléments de preuve présentés àf la Cour n’indiquent
pas que le programme de dragage du Nicaragua ait entraîné une quelf -
conque modification des caractéristiques écologiques de la zone hufmide,
ni qu’il ait été susceptible, à moins qu’il ne soit étfendu, d’avoir un tel

effet. Aussi la Cour en vient -elle à la conclusion que le Nicaragua n’était
tenu à aucune obligation d’informer le Secrétariat de la convenftion de
Ramsar.
110. La Cour rappelle par ailleurs le libellé de l’article 5 de la conven -
tion de Ramsar :

«Les Parties contractantes se consultent sur l’exécution des obligaf -
tions découlant de la Convention, particulièrement dans le cas d’fune
zone humide s’étendant sur les territoires de plus d’une Partief

contractante ou lorsqu’un bassin hydrographique est partagé entre f
plusieurs Parties contractantes. Elles s’efforcent en même temps dfe
coordonner et de soutenir leurs politiques et réglementations pré -
sentes et futures relatives à la conservation des zones humides, de
leur flore et de leur faune. »

Si cette disposition établit une obligation générale de consultation concer-
nant « l’exécution des obligations découlant de la Convention », elle

n’oblige pas le Nicaragua à consulter le Costa Rica au sujet d’un projet
particulier qu’il entreprend, en l’occurrence le dragage du cours finférieur
du fleuve San Juan. Il découle de ce qui précède que le Nicaragua n’étafit
pas tenu, au titre de la convention de Ramsar, d’informer ou de consuflter
le Costa Rica avant d’entreprendre son projet de dragage.
111. S’agissant de la convention concernant la conservation de la bio -

diversité et la protection des zones prioritaires de faune et de flfore sau -
vages d’Amérique centrale, la Cour estime qu’elle n’a pas à poursuivre

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5 Ord 1088.indb 92 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 709

and Nicaragua are parties to the Ramsar Convention and the Convention

for the Conservation of the Biodiversity and Protection of Priority
Wilderness Areas in Central America. The Court recalls that Article 3,
paragraph 2, of the Ramsar Convention provides that :

“Each Contracting Party shall arrange to be informed at the earli -
est possible time if the ecological character of any wetland in its ter -
ritory and included in the List [of wetlands of international importancef]

has changed, is changing or is likely to change as the result of tech -
nological developments, pollution or other human interference. Infor-
mation on such changes shall be passed without delay to the [Ramsar
Secretariat].”

While this provision contains an obligation to notify, that obligation ifs

limited to notifying the Ramsar Secretariat of changes or likely changesf
in the “ecological character of any wetland” in the territory of tfhe notify-
ing State. In the present case, the evidence before the Court does not
indicate that Nicaragua’s dredging programme has brought about any
changes in the ecological character of the wetland, or that it was likely to

do so unless it were to be expanded. Thus the Court finds that no obligaf -
tion to inform the Ramsar Secretariat arose for Nicaragua.

110. The Court further recalls that Article 5 of the Ramsar Convention
provides that:

“The Contracting Parties shall consult with each other about imple -
menting obligations arising from the Convention especially in the case
of a wetland extending over the territories of more than one Contract -
ing Party or where a water system is shared by Contracting Parties.
They shall at the same time endeavour to co -ordinate and support

present and future policies and regulations concerning the conserva -
tion of wetlands and their flora and fauna.”

While this provision contains a general obligation to consult “about f
implementing obligations arising from the Convention”, it does not crfe -
ate an obligation on Nicaragua to consult with Costa Rica concerning a
particular project that it is undertaking, in this case the dredging of fthe

Lower San Juan River. In light of the above, Nicaragua was not required f
under the Ramsar Convention to notify, or consult with, Costa Rica
prior to commencing its dredging project.
111. As to the Convention for the Conservation of the Biodiversity
and Protection of Priority Wilderness Areas in Central America, the

Court sees no need to take its enquiry further, as neither of the two prfov-i

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son examen, puisque ni l’une ni l’autre des dispositions de la confvention
invoquées par le Costa Rica n’impose une obligation de notification ou de

consultation.

c) Conclusion

112. A la lumière de ce qui précède, la Cour conclut qu’il n’af pas été
établi que le Nicaragua a manqué à de quelconques obligations dfe nature
procédurale lui incombant envers le Costa Rica au titre du droit interna -

tional conventionnel ou coutumier de l’environnement. Elle prend actef de
l’engagement du Nicaragua, formulé au cours de la procédure orafle, de
procéder à une nouvelle étude de l’impact sur l’environnement avant
toute expansion d’ampleur de son programme de dragage actuel. Elle
remarque par ailleurs que le Nicaragua a déclaré qu’il veillerafit à ce que

pareille étude comporte une analyse des risques de dommage transfron -
tière, et ferait en sorte d’informer et de consulter le Costa Rica dans le
cadre de ce processus.

2. Obligations de fond en matière de dommages transfrontières

113. La Cour a déjà conclu que la responsabilité du Nicaragua étafit
engagée à raison des dommages causés par les activités auxqufelles il s’est
livré en violation de la souveraineté territoriale du Costa Rica. Il reste à
déterminer si le Nicaragua est responsable de dommages transfrontièfres
qui auraient été causés par les activités de dragage qu’il a entreprises dans

des zones relevant de sa propre souveraineté territoriale, sur le coufrs infé-
rieur du San Juan et sa rive gauche.
114. Le Costa Rica fait valoir que le Nicaragua a manqué à « l’obliga-
tion de ne pas mener d’opérations de dragage, de déviation ou dfe modifi-
cation du cours du San Juan, ni d’autres travaux sur le fleuve San Juan

qui causeraient un dommage au territoire costa -ricien (y compris le
fleuve Colorado), à son environnement ou aux droits du Costa Rica
découlant de la sentence Cleveland de 1888» (conclusions finales,
point 2 c) v)). Il avance que, en mettant en œuvre son programme de
dragage dans le San Juan inférieur, le Nicaragua a manqué aux obliga -

tions qui lui incombaient au titre du droit international coutumier et
causé des dommages au territoire costa -ricien situé sur la rive droite du
fleuve, ainsi qu’au fleuve Colorado.
115. Le Nicaragua soutient pour sa part que le programme de dragage
n’a causé aucun dommage au territoire costa -ricien, y compris le

fleuve Colorado, considérant que sa mise en œuvre a été bénéfique à la
partie concernée du fleuve San Juan inférieur ainsi qu’aux zofnes humides
d’importance internationale situées en aval. Il avance par ailleurfs que, par
application d’une règle énoncée dans la sentence Cleveland et propre
au San Juan, même si des dommages devaient résulter, sur le territoire

costa-ricien, des travaux d’entretien et d’amélioration entrepris, lefs activi-
tés de dragage n’en seraient pas pour autant illicites.

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sions invoked by Costa Rica contains a binding obligation to notify or
consult.

(c) Conclusion

112. In light of the above, the Court concludes that it has not been
established that Nicaragua breached any procedural obligations owed to
Costa Rica under treaties or the customary international law of the envir-

onment. The Court takes note of Nicaragua’s commitment, made in the
course of the oral proceedings, to carry out a new Environmental Impact f
Study before any substantial expansion of its current dredging pro -
gramme. The Court further notes that Nicaragua stated that such a study f
would include an assessment of the risk of transboundary harm, and that f

it would notify, and consult with, Costa Rica as part of that process.

2. Substantive obligations concerning transboundary harm

113. The Court has already found that Nicaragua is responsible for the
harm caused by its activities in breach of Costa Rica’s territorial sover -
eignty. What remains to be examined is whether Nicaragua is responsible
for any transboundary harm allegedly caused by its dredging activities
which have taken place in areas under Nicaragua’s territorial sovereifgnty,

in the Lower San Juan River and on its left bank.

114. Costa Rica submits that Nicaragua has breached “the obligation
not to dredge, divert or alter the course of the San Juan River, or condfuct
any other works on the San Juan River, if this causes damage to

Costa Rican territory (including the Colorado River), its environment, or
to Costa Rican rights under the 1888 Cleveland Award” (final submis -
sions, para. 2 (c) (v)). According to Costa Rica, the dredging programme
executed by Nicaragua in the Lower San Juan River was in breach of
Nicaragua’s obligations under customary international law and caused

harm to Costa Rican lands on the right bank of the river and to the
Colorado River.

115. Nicaragua contends that the dredging programme has not caused
any harm to Costa Rican territory including the Colorado River. It

argues that the execution of the dredging programme has been beneficial f
to the dredged section of the Lower San Juan River and to the wetlands
of international importance lying downstream. Moreover, Nicaragua
maintains that, under a special rule stated in the Cleveland Award and
applying to the San Juan River, even if damage to Costa Rica’s territory

resulted from the works to maintain and improve the river, the dredging f
activities would not be unlawful.

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116. Les Parties se sont toutes deux référées au passage ci -après de la
sentence Cleveland :

«La République du Costa Rica ne peut empêcher la République
du Nicaragua d’exécuter à ses propres frais et sur son propre tferri -

toire de tels travaux d’amélioration, à condition que le territoire du
Costa Rica ne soit pas occupé, inondé ou endommagé en consé -
quence de ces travaux et que ceux -ci n’arrêtent pas ou ne perturbent
pas gravement la navigation sur ledit fleuve ou sur l’un quelconquef
de ses bras en aucun endroit où le Costa Rica a le droit de naviguer.

La République du Costa Rica aura le droit d’être indemnisée si des
parties de la rive droite du fleuve San Juan qui lui appartiennent sont
occupées sans son consentement ou si des terres situées sur cette
même rive sont inondées ou endommagées de quelque manière qufe
ce soit en conséquence de travaux d’amélioration. » (RSA,
vol. XXVIII, p. 210, point 6 du troisième paragraphe ; italiques dans

l’original [traduction du Greffe] .)
Un autre extrait de cette même sentence a également été citéf par l’une et

l’autre:
«La République du Costa Rica peut refuser à la République du

Nicaragua le droit de dévier les eaux du fleuve San Juan dans le cas
où une telle déviation arrêterait ou perturberait gravement la naviga -
tion sur ledit fleuve ou sur l’un quelconque de ses bras en tout enfdroit
où le Costa Rica a le droit de naviguer. » (Ibid., point 9 du troisième
paragraphe [traduction du Greffe].)

117. Le Nicaragua soutient que les passages précités de la sentence Cle-
veland signifient qu’il est libre d’entreprendre toutes activitéfs de dragage,
fussent -elles préjudiciables au Costa Rica. Selon ce dernier, cependant, le

Nicaragua aurait l’obligation de l’indemniser de tout dommage qui flui
serait causé, quelle qu’en soit l’importance et indépendammefnt de la dili-
gence dont il aurait pu faire preuve afin de préserver l’environnement
costa -ricien; ouvriraient également droit à indemnisation les dommages
résultant de tous « événements fortuits ou incontrôlables » liés aux activi-

tés de dragage du Nicaragua. Le Costa Rica a aussi fait valoir que « tous
les droits et obligations du Nicaragua découlant du traité de 1858 et de la
sentence de 1888 doivent être interprétés à la lumière des principes fde
protection de l’environnement actuellement en vigueur », et que ces
deux textes ne sauraient « supplanter les obligations en matière d’environ -

nement qui découlent des principes généraux du droit et des trafités inter-
nationaux» et qui interdisent aux Etats de causer des dommages
transfrontières importants.
118. Ainsi que la Cour l’a réaffirmé en l’affaire relative à fdesUsines de
pâte à papier, au regard du droit international coutumier, « l’Etat est tenu
de mettre en œuvre tous les moyens à sa disposition pour éviterf que les

activitésqui se déroulent sur son territoire, ou sur tout espace relevant de
sa juridiction, ne causent un préjudice sensible à l’environnemfent d’un

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116. Both Parties referred to the passage in the Cleveland Award which
reads as follows :

“The Republic of Costa Rica cannot prevent the Republic of Nic -
aragua from executing at her own expense and within her own terri -

tory such works of improvement, provided such works of improvement
do not result in the occupation or flooding or damage of Costa Rica
territory, or in the destruction or serious impairment of the navigationf
of the said river or any of its branches at any point where Costa Rica
is entitled to navigate the same. The Republic of Costa Rica has the

right to demand indemnification for any places belonging to her on
the right bank of the River San Juan which may be occupied without
her consent, and for any lands on the same bank which may be
flooded or damaged in any other way in consequence of works of
improvement.” (RIAA, Vol. XXVIII, p. 210, para. 3 (6); emphasis in
the original.)

Both Parties also referred to the following passage in the same Award :

“The Republic of Costa Rica can deny to the Republic of Nicara -

gua the right of deviating the waters of the River San Juan in case
such deviation will result in the destruction or serious impairment of
the navigation of the said river or any of its branches at any point
where Costa Rica is entitled to navigate the same.” (Ibid., para.3 (9).)

117. According to Nicaragua, the statements in the Cleveland Award
quoted above should be understood as implying that Nicaragua is free to f
undertake any dredging activity, possibly even if it is harmful to

Costa Rica. On the other hand, according to Costa Rica, Nicaragua
would be under an obligation to pay compensation for any harm caused
to Costa Rica, whether the harm was significant or not and whether Nica -
ragua was or was not diligent in ensuring that the environment of
Costa Rica would not be affected ;damage caused by “unforeseeable or

uncontrollable events” related to dredging activities would also havef to
be compensated by Nicaragua. Costa Rica also argued that “all of Nica -
ragua’s rights and obligations under the 1858 Treaty and the 1888 Award
must be interpreted in the light of principles for the protection of thef
environment in force today” and that the Treaty and the Award do not f

“override the application of environmental obligations under general f
principles of law and under international treaties” requiring States fnot to
cause significant transboundary harm.
118. As the Court restated in the Pulp Mills case, under customary
international law, “[a] State is . . obliged to use all the means at its dis -
posal in order to avoid activities which take place in its territory, orf in

any area under its jurisdiction, causing significant damage to the envirfon-
ment of another State” (I.C.J. Reports 2010 (I), p. 56, para. 101; see also

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autre Etat»(arrêt, C.I.J. Recueil 2010 (I), p. 56,par. 101; voir également
Licéité de la menace ou de l’emploi d’armes nucléaires, a▯vis consultatif,

C.I.J.Recueil 1996 (I), p. 241-242, par. 29).
Quoi qu’il en soit, la Cour n’aurait besoin d’examiner la questfion de
l’articulation entre le traité de 1858 tel qu’interprété par la sentence Cle -
veland et la règle actuelle du droit international coutumier relativef aux
dommages transfrontières que s’il était prouvé par le Costa Rica que le

programme de dragage mis en œuvre dans le fleuve San Juan inférifeur a
causé des dommages sur son territoire.
119. Or le Costa Rica n’a pas établi de manière convaincante que les sédi-
ments dragués du fleuve ont été déposés sur la rive drofite de cel-ci. Il n’a
pas davantage démontré que le programme de dragage a porté préfjudice à
sa zone humide (voir le paragraphe109 ci-dessus). S’agissant de l’allégation

du Costa Rica selon laquelle «le programme de dragage a eu des répercus-
sions importantes sur le fleuve Colorado», il a déjà été mentionné que les
Parties s’entendent sur le fait que, au point désigné «ta Colorado», envi-
ron 90 % des eaux du fleuve San Juan s’écoulent dans le fleuve Colorado
(voir le paragraphe 56 ci-dessus). Le Nicaragua estime à moins de 2 % la

proportion des eaux qui ont été détournées de ce dernier du ffait du dragage
du cours inférieur du SanJuan. Le CostaRica n’a avancé aucune valeur plus
élevée. Son expert principal a déclaré que «en ne prouve que le programme
de dragage ait eu une incidence sensible sur le débit du fleue olorado». Le
Costa Rica a certes produit des éléments de preuve indiquant que, entre

janvier 2011 et octobre 2014, le débit du fleuve Colorado aurait difminué de
manière significative. De l’avis de la Cour, toutefois, il n’a fpas été établi de
lien causal entre cette diminution et le programme de dragage du Nicaragfua.
Comme l’admet le Costa Rica, d’autres facteurs pourraient expliquefr cette
baisse de débit, au premier rang desquels figure le volume relativemefnt limité
de précipitations enregistrées pendant la période en question. fEn tout état de

cause, le détournement des eaux provoqué par le dragage du San Juan infé-
rieur est loin de perturber gravement la navigation sur le Colorado, hypfo -
thèse envisagée au point 9 du paragraphe3 de la sentence Cleveland,ou de
causer d’une autre manière des dommages au CostaRica.
120. En conséquence, la Cour conclut que les éléments de preuve dis -

ponibles ne montrent pas que le Nicaragua a manqué à ses obligatiofns en
s’engageant dans des activités de dragage sur le cours inférieufr du fleuve
San Juan.

C. Respect des mesures conservatoires

121. Le Costa Rica soutient, dans ses conclusions finales, que le Nica -
ragua a également manqué aux « obligations découlant des ordonnances
en indication de mesures conservatoires rendues par la Cour les 8 mars
2011 et 22 novembre 2013 » (point 2 c) vi)).
122. Le Nicaragua a quant à lui soulevé des questions concernant le

respect par le Costa Rica de certaines des mesures conservatoires indi -
quées, sans toutefois demander à la Cour de se prononcer à cet fégard.

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Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion,
I.C.J. Reports 1996 (I), pp. 241-242, para. 29).

In any event, it would be necessary for the Court to address the ques -
tion of the relationship between the 1858 Treaty as interpreted by the
Cleveland Award and the current rule of customary international law
with regard to transboundary harm only if Costa Rica were to prove that

the dredging programme in the Lower San Juan River produced harm to
Costa Rica’s territory.
119. Costa Rica has not provided any convincing evidence that sedi -
ments dredged from the river were deposited on its right bank. Costa Rica
has also not proved that the dredging programme caused harm to its wet -
land (see paragraph 109 above). With regard to Costa Rica’s contention

that “the dredging programme has had a significant effect upon the Coflo-
rado River”, it has already been noted that the Parties agree that atf the
so-called “Delta Colorado” the Colorado River receives about 90 per cent
of the waters flowing through the San Juan River (see paragraph 56
above). Nicaragua estimates that the diversion of water from the Colo -

rado River due to the dredging of the Lower San Juan River affected lessf
than 2 per cent of the waters flowing into the Colorado River. No higher
figure has been suggested by Costa Rica. Its main expert observed that
“there is no evidence that the dredging programme has significantly
affected flows in the Río Colorado”. Costa Rica did adduce evidence indi -

cating a significant reduction in flow of the Colorado River between Jan -
uary 2011 and October 2014. However, the Court considers that a causal
link between this reduction and Nicaragua’s dredging programme has noft
been established. As Costa Rica admits, other factors may be relevant to
the decrease in flow, most notably the relatively small amount of rainffall
in the relevant period. In any event, the diversion of water due to the f

dredging of the Lower San Juan River is far from seriously impairing
navigation on the Colorado River, as envisaged in paragraph 3 (9) of the
Cleveland Award, or otherwise causing harm to Costa Rica.

120. The Court therefore concludes that the available evidence does

not show that Nicaragua breached its obligations by engaging in dredgingf
activities in the Lower San Juan River.

C. Compliance with Provisional Measures

121. In its final submissions Costa Rica contends that Nicaragua has
also breached its “obligations arising from the Orders of the Court ifndi-
cating provisional measures of 8 March 2011 and 22 November 2013”
(para. 2 (c) (vi)).
122. Nicaragua, for its part, raised certain issues about Costa Rica’s

compliance with some of the provisional measures adopted by the Court,
but did not request the Court to make a finding on this matter.

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123. Dans son ordonnance du 8 mars 2011, la Cour indiquait que
chaque Partie devait « s’abst[enir] d’envoyer ou de maintenir sur le terri -

toire litigieux, y compris le caño, des agents, qu’ils soient civils, de police
ou de sécurité », et par ailleurs « s’abst[enir] de tout acte qui risquerait
d’aggraver ou d’étendre le différend dont [elle] [était] fsaisie ou d’en rendre
la solution plus difficile» (C.I.J. Recueil 2011 (I), p. 27, par. 86).
124. Le Costa Rica a fait valoir que la présence sur le territoire liti -

gieux de groupes importants de civils nicaraguayens membres d’un mou -
vement de défense de l’environnement emportait violation de l’ofrdonnance
de 2011, ce qu’a contesté le Nicaragua. Dans son ordonnance du 16 juillet
2013, la Cour a précisé que « la présence de groupes organisés de ressor -
tissants nicaraguayens dans le territoire litigieux comport[ait] un risque
d’incidents susceptibles d’aggraver le … différend » (C.I.J. Recueil 2013,

p. 240, par. 37).
125. Ainsi que le Costa Rica l’a fait valoir et que le Nicaragua l’a
admis par la suite, le creusement des deuxième et troisième caños a eu lieu
après le prononcé de l’ordonnance de 2011, cette activité est attribuable
au Nicaragua et un campement militaire a par ailleurs été établfi sur le

territoire litigieux tel que défini par la Cour. Le Nicaragua a égfalement
reconnu à l’audience que le creusement des deuxième et troisième caños
emportait manquement aux obligations lui incombant au titre de l’ordofn -
nance de 2011.
126. Ces faits ont déjà été constatés dans l’ordonnance de fla Cour en

date du 22 novembre 2013 (ibid., p. 364-365, par. 45-46), mais à seule fin
d’assurer la protection des droits des Parties pendant la procédurfe. C’est
au stade de l’arrêt au fond qu’il convient d’apprécier lef respect des
mesures conservatoires. Ainsi, contrairement à ce que soutient le Nicfara -
gua, l’on ne saurait considérer qu’il serait « superfl[u]» de constater, dans
le présent arrêt, l’existence d’une violation, pas plus que fl’on ne saurait

affirmer que la responsabilité y afférente a cessé : la violation peut avoir
pris fin, mais pas la responsabilité qui en découle.

127. Sur la base des faits qui sont désormais incontestés, la Cour
conclut en conséquence que, en creusant deux caños et en établissant une

présence militaire sur le territoire litigieux, le Nicaragua a manquéf aux
obligations qui lui incombaient au titre de l’ordonnance du 8 mars 2011.
128. Dans son ordonnance du 22 novembre 2013, la Cour a prescrit au
Nicaragua de:« s’abstenir de toute activité de dragage ou autre activité dans
le territoire litigieux»; de «combler la tranchée creusée sur la plage au nord

du caño oriental »; d’«assurer le retrait du territoire litigieux de tous agents,
qu’ils soient civils, de police ou de sécurité »; d’«empêcher l’entrée de tels
agents dans ledit territoire»; et d’«assurer le retrait du territoire litigieux de
toutes personnes privées relevant de sa juridiction ou sous son contrfôle et
empêcher leur entrée dans ledit territoire » ( ibid., p. 369, par. 59). Le
Costa Rica n’a formulé aucune allégation de manquement ultérieur àf ces

obligations, se bornant à soutenir que certaines des activités entfreprises par
le Nicaragua après cette nouvelle ordonnance emportaient manquement àf

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123. In its Order on provisional measures of 8 March 2011 the Court
indicated that “[e]ach Party shall refrain from sending to, or maintafining in

the disputed territory, including the caño, any personnel, whether civilian,
police or security”; the Court also required each Party to “refrain from any
action which might aggravate or extend the dispute before the Court or
make it more difficult to resolve” (I.C.J.Reports 2011 (I), p. 27, para. 86).
124. Costa Rica argued that the presence in the disputed territory of

large groups of Nicaraguan civilians who were members of an environ -
mental movement constituted a breach of the 2011 Order. Nicaragua
denied this. In its Order of 16 July 2013, the Court specified that “the
presence of organized groups of Nicaraguan nationals in the disputed
area carrie[d] the risk of incidents which might aggravate the . . . dispute”
(I.C.J. Reports 2013, p. 240, para. 37).

125. Costa Rica maintained and Nicaragua later acknowledged that
the excavation of the second and third caños took place after the 2011
Order had been adopted, that this activity was attributable to Nicaraguaf
and that moreover a military encampment had been installed on the dis -

puted territory as defined by the Court. In the oral hearings Nicaragua f
also acknowledged that the excavation of the second and third caños rep-
resented an infringement of its obligations under the 2011 Order.

126. The Court already ascertained these facts in its Order of

22 November 2013 (ibid., pp. 364-365, paras. 45-46). However, that state-
ment was only instrumental in ensuring the protection of the rights of tfhe
Parties during the judicial proceedings. The judgment on the merits is tfhe
appropriate place for the Court to assess compliance with the provisionafl
measures. Thus, contrary to what was argued by Nicaragua, a statement
of the existence of a breach to be included in the present Judgment cannfot

be viewed as “redundant”. Nor can it be said that any responsibilifty for
the breach has ceased : what may have ceased is the breach, not the
responsibility arising from the breach.
127. On the basis of the facts that have become uncontested, the Court
accordingly finds that Nicaragua breached its obligations under the Ordefr

of 8 March 2011 by excavating two caños and establishing a military pres -
ence in the disputed territory.
128. The Court’s Order of 22 November 2013 required the following
measures from Nicaragua: to “refrain from any dredging and other activ-
ities in the disputed territory” ; to “fill the trench on the beach north of

the eastern caño” ; to “cause the removal from the disputed territory of
any personnel, whether civilian, police or security” ; to “prevent any such
personnel from entering the disputed territory” ; and to “cause the
removal from and prevent the entrance into the disputed territory of anyf
private persons under its jurisdiction or control” ( ibid., p. 369, para. 59).
No allegations of subsequent breaches of any of these obligations were

made by Costa Rica, which only maintained that some of Nicaragua’s
activities after this Order were in breach of its obligation not to aggrfavate

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l’obligation de ne pas aggraver le différend énoncée dans l’fordonnance
de 2011. De l’avis de la Cour, le manquement à cette obligation n’a pas été

établi par les éléments de preuve versés au dossier.
129. En conséquence, la Cour conclut que, en creusant les deuxième et
troisième caños et en établissant une présence militaire sur le territoire
litigieux, le Nicaragua a manqué aux obligations qui lui incombaient fau
titre de l’ordonnance de 2011. Il est précisé que cette conclusion est indé -

pendante de celle qui a été formulée ci -dessus (voir section A) et selon
laquelle ces mêmes agissements emportent également violation de laf sou-
veraineté territoriale du Costa Rica.

D. Droits de navigation

130. Dans ses conclusions finales, le Costa Rica avance par ailleurs que
le Nicaragua a violé « les droits perpétuels de libre navigation dont [il]
peut se prévaloir sur le San Juan conformément au traité de limites
de 1858, à la sentence Cleveland de 1888 et à l’arrêt de la Cour du 13 juil-

let 2009» (conclusions finales, point 2 c) ii)).
131. Le Nicaragua conteste la recevabilité de cette conclusion, au motif
que celle-ci n’entre pas dans le cadre de la requête et que son objet est
sans rapport avec celui du « litigeprincipal». Le Costa Rica fait remar-
quer qu’il a déjà, dans sa requête (point 41 f)), prié la Cour de dire et

juger que, « par son comportement, le Nicaragua a[vait] violé … l’obliga -
tion de ne pas interdire la navigation de ressortissants costa -riciens sur le
San Juan ».
132. La Cour observe que, s’il est vrai que cette conclusion du Costa
Rica pourrait être comprise comme se rapportant aux « activités de

dragage et de creusement d’un canal qu[e le Nicaragua] m[enait] … dans
le San Juan», dont il était également question au même paragraphe de laf
requête, rien dans sa formulation ne permet d’affirmer qu’ellef s’y limitait.
La Cour considère que la conclusion finale du Costa Rica concernant les
droits de navigation est recevable.

133. L’article VI du traité de 1858 énonce ce qui suit :
« La République du Nicaragua aura le dominium et l’imperium

exclusifs sur les eaux du fleuve San Juan depuis son origine dans le
lac jusqu’à son embouchure dans l’océan Atlantique; la République
du Costa Rica aura toutefois un droit perpétuel de libre navigation
sur lesdites eaux, entre l’embouchure du fleuve et un point situéf à
trois milles anglais en aval de Castillo Viejo, [con objetos de comer ‑

cio], soit avec le Nicaragua soit avec l’intérieur du Costa Rica par la
rivière San Carlos, la rivière Sarapiquí ou toute autre voie de naviga-
tion partant de la portion de la rive du San Juan établie comme
appartenant à cette république. Les bateaux des deux pays pourrontf
accoster indistinctement sur l’une ou l’autre rive de la portion dfu

fleuve où la navigation est commune, sans qu’aucune taxe ne soit
perçue, sauf accord entre les deux gouvernements. » Différend relatif

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the dispute, which had been stated in the 2011 Order. The Court does notf
find that a breach of this obligation has been demonstrated on the basisf

of the available evidence.
129. The Court thus concludes that Nicaragua acted in breach of its
obligations under the 2011 Order by excavating the second and third
caños and by establishing a military presence in the disputed territory.
The Court observes that this finding is independent of the conclusion seft

out above (see Section A) that the same conduct also constitutes a viola -
tion of the territorial sovereignty of Costa Rica.

D. Rights of Navigation

130. In its final submissions Costa Rica also claims that Nicaragua has
breached “Costa Rica’s perpetual rights of free navigation on the San
Juan in accordance with the 1858 Treaty of Limits, the 1888 Cleveland
Award and the Court’s Judgment of 13 July 2009” (final submissions,

para. 2 (c) (ii)).
131. Nicaragua contests the admissibility of this submission, which it
considers not covered by the Application and as having an object uncon -
nected with that of the “main dispute”. Costa Rica points out that it had
already requested in its Application (para. 41 (f)) that the Court adjudge

and declare that, “by its conduct, Nicaragua has breached . . . the obliga-
tion not to prohibit the navigation on the San Juan River by Costa Rican
nationals”.
132. The Court observes that, although Costa Rica’s submission could
have been understood as related to the “dredging and canalization activi -

ties being carried out by Nicaragua on the San Juan River”, to which fthe
same paragraph of the Application also referred, the wording of the sub -
mission quoted above did not contain any restriction to that effect. Thef
Court considers that Costa Rica’s final submission concerning rights of
navigation is admissible.

133. Article VI of the 1858 Treaty provides that :
“The Republic of Nicaragua shall have exclusive dominium and

imperium over the waters of the San Juan River from its origin in the
lake to its mouth at the Atlantic Ocean ; the Republic of Costa Rica
shall however have a perpetual right of free navigation on the said
waters between the mouth of the river and a point located three Eng-
lish miles below Castillo Viejo, [con objetos de comercio], whether

with Nicaragua or with the interior of Costa Rica by the rivers San
Carlos or Sarapiquí or any other waterway starting from the section
of the bank of the San Juan established as belonging to that Repub -
lic. The vessels of both countries may land indiscriminately on either
bank of the section of the river where navigation is common, without

paying any taxes, unless agreed by both Governments.” (Translation
from the Spanish original as reproduced in Dispute regarding Naviga‑

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à des droits de navigation et des droits connexes (Costa Rica c. Nica‑

ragua), arrêt, C.I.J. Recueil 2009, p. 236, par. 44; traduction établie
à partir de l’original en espagnol : La República de Nicaragua tendrá
exclusivamente el dominio y sumo imperio sobre las aguas del río de
San Juan desde su salida del Lago, hasta su desembocadura en el
Atlántico ; pero la República de Costa Rica tendrá en dichas aguas los

derechos perpetuos de libre navegación, desde la expresada desemboca‑
dura hasta tres millas inglesas antes de llegar al Castillo Viejo, con
objetos de comercio, ya sea con Nicaragua ó al interior de Costa Rica,
por los ríos de San Carlos ó Sarapiquí, ó cualquiera otra ví▯a proce ‑

dente de la parte que en la ribera del San Juan se establece correspon‑
der á esta República. Las embarcaciones de uno ú otro país p▯odrán
indistintamente atracar en las riberas del río en la parte en que la ▯nave‑
gación es común, sin cobrarse ninguna clase de impuestos, á no ▯ser que
se establezcan de acuerdo entre ambos Gobiernos. ) »

La sentenceCleveland contient quelques références, dans les passages précif -
tés (voir le paragraphe 116), aux droits de navigation du Costa Rica. Dans

l’arrêt qu’elle a rendu en l’affaire duDifférend relatif à des droits de naviga‑
tion et des droits connexes (CostaRica c. Nicaragua), la Cour a observé que

« deux types de navigation privée sont certainement couverts par le
droit de libre navigation au titre de l’article VI du traité de 1858 : la
navigation des bateaux transportant des marchandises destinées à
donner lieu à des actes de commerce; et celle des bateaux transportant

des passagers qui acquittent un prix autre que symbolique (ou pour le
compte desquels est acquitté un tel prix) en contrepartie du service qui
leur est ainsi fourni» (C.I.J. Recueil 2009, p. 245, par. 73).

Bien que l’article VI du traité de 1858 n’envisage expressément que la
navigation aux fins de commerce, la Cour a également indiqué ce qufi suit :

« il n’a[vait] pas pu être dans l’intention des auteurs du traitéf de1858
de dénier aux habitants de la rive costa -ricienne du fleuve, là où cette
rive constitue la frontière entre les deux Etats, le droit d’emprunter le
fleuve dans la mesure nécessaire à la satisfaction de leurs besoins

essentiels, compte tenu de la configuration des lieux, et en dehors
même de toute activité de nature commerciale » (ibid., p. 246, par. 79).

Dans le dispositif du même arrêt, la Cour a conclu que

« les habitants de la rive costa-ricienne du fleuve San Juan [avaient] le
droit de naviguer sur celui -ci entre les communautés riveraines afin de
subvenir aux besoins essentiels de la vie quotidienne qui nécessit[aifent]
des déplacements dans de brefs délais » (ibid., p. 270, par. 156 1) f)).

134. Au nombre des atteintes qui auraient été portées à ses droitfs de
navigation, le Costa Rica reproche au Nicaragua d’avoir pris le
décret n 079-2009 du 1 er octobre 2009 concernant la navigation sur le

San Juan. Les Parties sont en désaccord sur l’interprétation qu’fil convient

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tional and Related Rights (Costa Rica v. Nicaragua), Judgment,
I.C.J. Reports 2009, p. 236, para. 44: “La República de Nicaragua

tendrá exclusivamente el dominio y sumo imperio sobre las aguas del
río de San Juan desde su salida del Lago, hasta su desembocadura en
el Atlántico ; pero la República de Costa Rica tendrá en dichas aguas
los derechos perpetuos de libre navegación, desde la expresada desem ‑
bocadura hasta tres millas inglesas antes de llegar al Castillo Viejo, con

objetos de comercio, ya sea con Nicaragua ó al interior de Costa Rica,
por los ríos de San Carlos ó Sarapiquí, ó cualquiera otra vía procedente
de la parte que en la ribera del San Juan se establece corresponder á
esta República. Las embarcaciones de uno ú otro país podrán indistin ‑
tamente atracar en las riberas del río en la parte en que la navegaci▯ón

es común, sin cobrarse ninguna clase de impuestos, á no ser que se▯
establezcan de acuerdo entre ambos Gobiernos.” )

The Cleveland Award contains some references to Costa Rica’s rights of
navigation that were quoted above (see paragraph 116). In its Judgment
in Dispute regarding Navigational and Related Rights (Costa Rica v. Nica‑
ragua), the Court noted that :

“two types of private navigation are certainly covered by the right off
free navigation pursuant to Article VI of the 1858 Treaty: the navi-

gation of vessels carrying goods intended for commercial transac -
tions; and that of vessels carrying passengers who pay a price other
than a token price (or for whom a price is paid) in exchange for the
service thus provided” ( I.C.J. Reports 2009, p. 245, para. 73).

While the express language of Article VI of the 1858 Treaty only consid-
ered navigation for purposes of commerce, the Court also observed that :

“it cannot have been the intention of the authors of the 1858 Treaty
to deprive the inhabitants of the CostaRican bank of the river, where

that bank constitutes the boundary between the two States, of the
right to use the river to the extent necessary to meet their essential
requirements, even for activities of a non -commercial nature, given
the geography of the area” (ibid., p. 246, para. 79).

In the operative part of the same Judgment, the Court found that :

“the inhabitants of the Costa Rican bank of the San Juan River have
the right to navigate on the river between the riparian communities
for the purposes of the essential needs of everyday life which require
expeditious transportation” (ibid., p. 270, para. 156 (1) (f)).

134. Costa Rica includes among the alleged breaches of its rights of
navigation the enactment by Nicaragua of Decree No. 079-2009 of

1 October 2009, concerning navigation on the San Juan River. The inter -
pretation of this decree is controversial between the Parties : Costa Rica

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de donner à ce texte l: Costa Rica considère qu’il est d’application géné-

rale, tandis que le Nicaragua soutient qu’il s’applique seulement faux
bateaux de tourisme. La Cour observe que, s’il va de soi que le défcret
n o079-2009 devrait être conforme à l’articleVI du traité de 1858, tel qu’elle
l’a interprété, aucun des incidents spécifiquement invoquéfs par le CosR taica
au titre de l’entrave à ses droits de navigation n’a trait àf l’application de ce

texte. Il n’y a donc pas lieu pour la Cour d’examiner ce décretf.
135. Selon le Costa Rica, il a été porté atteinte à ses droits de navigation
dans le cadre de cinq incidents. S’il souligne le nombre peu élevéf des viola -
tions alléguées, le Nicaragua ne nie pas que deux de ces incidents ont eu lieu.
Dans le premier cas, en février2013, un agriculteur riverain et son oncle ont
été retenus pendant plusieurs heures à un poste de l’arméfe nicaraguayenne,

où ils ont été soumis à des traitements humiliants. Cet incifdent est relaté
dans une déclaration sous serment. Dans le second cas, en juin 2014, un
citoyen costa-ricien et des membres d’une coopérative agricole locale se sont
vu interdire la navigation sur le fleuve San Juan par des agents nicara -
guayens, ainsi que cela est confirmé par cinq déclarations sous sefrment.

136. La Cour estime que le Nicaragua n’a pas apporté de justification
convaincante, au regard de l’article VI du traité de 1858, de la conduite de
ses agents lors des deux incidents susmentionnés qui concernent la nafvi -
gation sur le fleuve San Juan par des personnes habitant la rive costaf-
ricienne de celui-ci. La Cour conclut que, en raison des deux incidents en

cause, le Nicaragua a violé les droits de navigation sur le fleuve fSan Juan
que le Costa Rica tient du traité de 1858. Compte tenu de cette conclu -
sion, il n’est pas nécessaire pour la Cour d’examiner les autrefs incidents
allégués par le Costa Rica.

E. Réparations

137. Le Costa Rica prie la Cour d’ordonner au Nicaragua d’« abroger,
par les moyens de son choix, les dispositions du décret n o 079-2009 et du
règlement y annexé en date du 1 eroctobre 2009 qui sont contraires au
droit de libre navigation reconnu au Costa Rica par l’article VI du traité

de limites de 1858, la sentence Cleveland de 1888 et l’arrêt de la Cour du
13 juillet 2009», et de cesser toute activité de dragage du fleuve San Juan
en attendant que certaines conditions soient satisfaites (conclusions
finales, points 3 a) et b)).
Le Costa Rica demande par ailleurs à la Cour d’ordonner au Nicara -

gua :
« d’apporter réparation, par voie d’indemnisation, à raison des dom -
mages matériels causés au Costa Rica, à savoir notamment, mais

non exclusivement : i)les dommages découlant de la construction des
caños artificiels et de la destruction des arbres et de la végétation sfur
le « territoire litigieux »; ii)s dépenses engagées par le Costa Rica
pour remédier à ces dommages … le montant de cette indemnisation
devant être déterminé lors d’une phase distincte de la procéfdure »

(ibid., point 3 c)).

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considers that the decree is of general application, whereas Nicaragua
contends that it applies only to tourist boats. While it is clear that tfhe

decree should be consistent with Article VI of the 1858 Treaty as inter -
preted by the Court, the Court observes that none of the instances of
interference with Costa Rica’s rights of navigation specifically alleged by
Costa Rica relates to the application of Decree No. 079-2009. The Court
is therefore not called upon to examine this decree.
135. Costa Rica alleges that breaches of its rights of navigation

occurred in five instances. Nicaragua emphasizes the small number of
alleged breaches, but does not contest two of those incidents. In the fifrst
one, in February 2013, a riparian farmer and his uncle were detained forf
several hours at a Nicaraguan army post and subjected to humiliating
treatment. This incident is set out in an affidavit. In the second incifdent,

in June 2014, a Costa Rican property owner and some members of a local
agricultural co-operative were prevented by Nicaraguan agents from nav -
igating the San Juan River. This is supported by five affidavits.

136. The Court finds that Nicaragua did not provide a convincing jus-
tification with regard to Article VI of the 1858 Treaty for the conduct of

its authorities in these two incidents concerning navigation by inhabitafnts
of the Costa Rican bank of the San Juan River. The Court concludes that
the two incidents show that Nicaragua breached Costa Rica’s rights of
navigation on the San Juan River pursuant to the 1858 Treaty. Given this
finding, it is unnecessary for the Court to examine the other incidents f
invoked by Costa Rica.

E. Reparation

137. Costa Rica requests the Court to order Nicaragua to “repeal, by
means of its own choosing, those provisions of the Decree No. 079-2009

and the Regulatory Norms annexed thereto of 1 October 2009 which are
contrary to Costa Rica’s right of free navigation under Article VI of the
1858 Treaty of Limits, the 1888 Cleveland Award, and the Court’s Judg -
ment of 13 July 2009” and to cease all dredging activities in the San Juan
River pending the fulfilment of certain conditions (final submissions, f
para. 3 (a) and (b)).

Costa Rica moreover asks the Court to order Nicaragua to :

“make reparation in the form of compensation for the material dam-

age caused to Costa Rica, including but not limited to: (i) damage
arising from the construction of artificial caños and destruction of
trees and vegetation on the ‘disputed territory’; (ii) the cost of the
remediation measures carried out by Costa Rica in relation to those
damages . . .; the amount of such compensation to be determined in

a separate phase of these proceedings” ( ibid., para. 3 (c)).

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Il est également demandé à la Cour d’ordonner au Nicaragua df’« appor-
ter réparation, par voie de satisfaction, pour remédier pleinementf au pré-

judice causé au Costa Rica, selon des modalités déterminées par la Cour »
(conclusions finales, point 3 d)) et de « fournir des assurances et garanties
appropriées de non -répétition du comportement illicite du Nicaragua,
selon des modalités déterminées par la Cour » (ibid., point 3) e)). Le
Costa Rica sollicite enfin le remboursement de certains de ses frais de

procédure, point qui sera examiné plus loin dans la présente sefction.
138. Etant donné les conclusions auxquelles elle est parvenue aux sec -
tions B et D ci -dessus, la Cour ne peut faire droit aux demandes présen -
tées par le Costa Rica aux points 3 a) et b) de ses conclusions finales, qui
concernent respectivement l’abrogation du décret n o 079-2009 relatif à la
navigation et la cessation des activités de dragage.

139. La constatation par la Cour de ce que le Nicaragua a violé
la souveraineté territoriale du Costa Rica en creusant trois caños et en
établissant une présence militaire sur le territoire litigieux confstitue une
satisfaction appropriée au préjudice immatériel subi à ce tiftre. Il en va de
même de la constatation de la violation des obligations découlant fde

l’ordonnance en indication de mesures conservatoires rendue par la
Cour le 8 mars 2011. Enfin, la constatation de la violation, dans les condi -
tions rappelées à la section D ci-dessus, des droits de navigation conférés
au Costa Rica constitue également une satisfaction appropriée à cet
égard.

140. La demande tendant à la fourniture d’« assurances et garanties
appropriées de non -répétition» a été présentée en raison, initialement, de
la « mauvaise foi » reprochée au Nicaragua dans le cadre du dragage du
caño de 2010, puis de la méconnaissance des obligations lui incombant au f
titre de l’ordonnance de 2011.
141. Ainsi que la Cour l’a rappelé à l’occasion du Différend relatif à

des droits de navigation et des droits connexes, « il n’y a pas lieu de suppo -
ser que l’Etat dont un acte ou un comportement a été déclaré illicite par
la Cour répétera à l’avenir cet acte ou ce comportement, puifsque sa bonne
foi doit être présumée », de sorte que seules des « circonstances spéciales»
peuvent justifier que soit ordonnée la fourniture d’assurances et fde garan-

ties de non -répétition (C.I.J. Recueil 2009, p. 267, par. 150). Bien que le
Nicaragua ait manqué aux obligations découlant de l’ordonnance fde 2011,
il convient de prendre également en considération le fait qu’ilf s’est par la
suite conformé à celles, énoncées dans l’ordonnance du 22f novembre
2013, de « s’abstenir de toute activité de dragage ou autre activité dans fle

territoire litigieux » et d’« assurer le retrait du territoire litigieux de tous
agents, qu’ils soient civils, de police ou de sécurité » (C.I.J. Recueil 2013,
p. 369, par. 59). Il y a tout lieu de penser que le Nicaragua adoptera la
même attitude à l’égard de la situation de droit résultanft du présent arrêt,
compte tenu notamment du fait que la question de la souveraineté terrfi -
toriale sur le territoire litigieux est désormais réglée.

142. Le Costa Rica est fondé à recevoir indemnisation pour les dom -
mages matériels découlant des violations dont la Cour a constatéf la com-

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The Court is further requested to order Nicaragua to “provide satisfafc -
tion so [as] to achieve full reparation of the injuries caused to Costa Rica

in a manner to be determined by the Court” (final submissions,
para. 3 (d)) and to “provide appropriate assurances and guarantees of
non-repetition of Nicaragua’s unlawful conduct, in such a form as the
Court may order” (ibid., para. 3 (e)). Costa Rica finally requests an
award of costs that will be considered later in the present section.

138. In view of the conclusions reached by the Court in SectionB s and D
above, the requests made by Costa Rica in its final submissions under
paragraph 3 (a) and (b), concerning the repeal of the DecreeNo. 079-2009
on navigation and the cessation of dredging activities respectively, canfnot
be granted.

139. The declaration by the Court that Nicaragua breached the territo -
rial sovereignty of Costa Rica by excavating three caños and establishing
a military presence in the disputed territory provides adequate satisfacf -
tion for the non -material injury suffered on this account. The same applies
to the declaration of the breach of the obligations under the Court’sf

Order of 8 March 2011 on provisional measures. Finally, the declaration
of the breach of Costa Rica’s rights of navigation in the terms determined
above in Section D provides adequate satisfaction for that breach.

140. The request for “appropriate assurances and guarantees of
non-repetition” was originally based on Nicaragua’s alleged “bad fafith”
in the dredging of the 2010 caño and later on Nicaragua’s infringement of
its obligations under the 2011 Order.

141. As the Court noted in the Navigational and Related Rights case,

“there is no reason to suppose that a State whose act or conduct has fbeen
declared wrongful by the Court will repeat that act or conduct in the
future, since its good faith must be presumed” and therefore assurancfes
and guarantees of non-repetition will be ordered only “in special circum -
stances” (I.C.J. Reports 2009, p. 267, para. 150). While Nicaragua failed

to comply with the obligations under the 2011 Order, it is necessary also
to take into account the fact that Nicaragua later complied with the
requirements, stated in the Order of 22 November 2013, to “refrain from
any dredging and other activities in the disputed territory” and to “fcause
the removal from the disputed territory of any personnel, whether civil -

ian, police or security” (I.C.J. Reports 2013, p. 369, para. 59). It is to be
expected that Nicaragua will have the same attitude with regard to the
legal situation resulting from the present Judgment, in particular in vifew
of the fact that the question of territorial sovereignty over the disputfed
territory has now been resolved.

142. Costa Rica is entitled to receive compensation for the material
damage caused by those breaches of obligations by Nicaragua that have

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mission par le Nicaragua. La Cour ne pourrait procéder à l’éfvaluation de
ces dommages et du montant de l’indemnité que dans le cadre d’ufne pro-
cédure distincte. La Cour estime que les Parties devraient mener des
négociations afin de s’entendre sur ces questions. Toutefois, si eflles ne
parviennent pas à un accord dans un délai de 12 mois à partir de la date

du présent arrêt, la Cour déterminera, à la demande de l’fune d’entre elles,
le montant de l’indemnité sur la base de pièces écrites addiftionnelles limi
tées à cet objet.

*

143. Le Costa Rica prie par ailleurs la Cour d’ordonner au Nicaragua
de:

«s’acquitter, sur la base d’une obligation d’indemnisation complfète,
de tous les frais engagés par le Costa Rica dans le cadre de la procé -
dure de demande en indication de mesures conservatoires qui s’est

conclue par le prononcé de l’ordonnance du 22 novembre 2013, à
savoir notamment, mais non exclusivement, les honoraires et frais de
ses conseils et experts, majorés d’intérêts » (conclusions finales,
point 3 f)).

La raison qui sous -tend spécifiquement cette demande tient à ce que la
procédure ayant abouti à l’ordonnance du 22 novembre 2013 aurait été
engagée à raison du manquement par le Nicaragua aux obligations lufi

incombant au titre de l’ordonnance du 8 mars 2011.
144. Aux termes de l’article 64 du Statut, « [s]’il n’en est autrement
décidé par la Cour, chaque partie supporte ses frais de procédufre ». Cet
article dispose que, en règle générale, aucune des parties n’fest condamnée

à supporter les frais de procédure, mais confère à la Cour le pouvoir de
mettre tout ou partie de ceux -ci à la charge de l’une d’elles. Bien que, en
ne respectant pas les prescriptions de l’ordonnance de 2011, le Nicaragua
ait conduit le Costa Rica à engager une nouvelle procédure en indifcation
de mesures conservatoires, la Cour considère que, compte tenu de l’fen -

semble des circonstances de l’espèce, la condamnation du Nicaraguaf à
supporter certains frais de procédure du Costa Rica, comme celui-ci l’a
demandé, ne serait pas appropriée.

IV. Questions en litige efn l’affaire N iCaRagua c. osta RiCa

145. Dans la requête qu’il a déposée le 22 décembre 2011 (voir le para-
graphe 9 ci-dessus), le Nicaragua allègue que, à l’occasion de la construcf-

tion de la route le long du fleuve San Juan, le Costa Rica a manqué à des
obligations de nature tant procédurale que substantielle. La Cour comf -
mencera par examiner les allégations de manquement à des obligations
d’ordre procédural, avant de se pencher sur celles concernant le mfanque-
ment à des obligations de fond.

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5 Ord 1088.indb 110 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 718

been ascertained by the Court. The relevant material damage and the
amount of compensation may be assessed by the Court only in separate
proceedings. The Court is of the opinion that the Parties should engage fin
negotiation in order to reach an agreement on these issues. However, if
they fail to reach such an agreement within 12 months of the date of the

present Judgment, the Court will, at the request of either Party, determfine
the amount of compensation on the basis of further written pleadings
limited to this issue.

*

143. Costa Rica also requests the Court to order Nicaragua to :

“pay all of the costs and expenses incurred by Costa Rica in request-
ing and obtaining the Order on provisional measures of 22 November
2013, including, but not limited to, the fees and expenses of

Costa Rica’s counsel and experts, with interest, on a full indemnity
basis” (final submissions, para. 3 (f)).

The special reason for this request is that the proceedings which led tof the
Order of 22 November 2013 were allegedly due to the infringements by
Nicaragua of its obligations under the Order of 8 March 2011.

144. According to Article 64 of the Statute, “[u]nless otherwise decided
by the Court, each party shall bear its own costs”. This Article provfides
that as a rule, costs are not awarded to any of the parties, but gives tfhe

Court the power to order that one of them will pay some or all of the
costs. While the breach by Nicaragua of its obligations under the
2011 Order necessitated Costa Rica engaging in new proceedings on pro -
visional measures, the Court finds that, taking into account the overallf
circumstances of the case, an award of costs to Costa Rica, as the latter

requested, would not be appropriate.

IV. Issues in the NiCaRagua v. Costa R iCa Case

145. The Application filed by Nicaragua on 22 December 2011 (see
paragraph 9 above) concerns the alleged breach by Costa Rica of both

procedural and substantive obligations in connection with the construc -
tion of the road along the San Juan River. The Court will start by consifd-
ering the alleged breach of procedural obligations ; then it will address the
alleged breach of substantive obligations.

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A. Allégations de violation d’obligations de nature procédurale

1. Allégation de violation de l’obligation d’effectuer une éval▯uation de

l’impact sur l’environnement

146. Selon le Nicaragua, le Costa Rica a manqué à l’obligation qui lui
incombait au titre du droit international général d’évaluer,f avant le début
des travaux, l’impact environnemental de la construction de la route,f
compte tenu en particulier de la longueur et de l’emplacement de cellfe-ci.
147. Le Costa Rica conteste cette allégation, arguant que la construc -

tion de la route ne présentait pas de risque de dommage transfrontièfre
important à raison du rejet de substances nocives dans le San Juan ou
ailleurs sur le territoire nicaraguayen, et que les quantités relativfement
négligeables de sédiments provenant de la route ne risquaient pas fd’avoir
une incidence sensible sur le fleuve.

148. Le Costa Rica avance par ailleurs qu’il était dispensé de l’obliga -
tion d’effectuer une évaluation de l’impact sur l’environnemfent en raison
de l’état d’urgence que le Nicaragua avait provoqué en occupant Isla Por-
tillos (voir les paragraphes 63-64 ci-dessus). En premier lieu, il fait valoir
qu’une situation d’urgence peut exempter un Etat de l’obligatiofn de pro-

céder à une évaluation de l’impact sur l’environnement, qfue ce soit parce
que le droit international renvoie sur ce point au droit interne ou parcfe
qu’il prévoit une dérogation en cas d’urgence. En second liefu, il affirme
que la construction de la route constituait une réponse appropriéef à la
situation d’urgence, en ce qu’elle devait faciliter l’accès faux postes de

police et aux communautés isolées situés le long de la rive droite du
San Juan, compte tenu notamment du risque réel d’un affrontement mili -
taire avec le Nicaragua, lequel contraindrait le Costa Rica à procéfder à
l’évacuation de la région. La construction pouvait donc, selon flui, être
entreprise sans évaluation de l’impact sur l’environnement.

149. En tout état de cause, le Costa Rica soutient que, même s’il avait
en l’occurrence été tenu, au titre du droit international, de rféaliser une
évaluation de l’impact sur l’environnement, il a satisfait àf cette obligation
puisqu’il a effectué un certain nombre d’études de l’impafct sur l’environ -
nement, dont un « diagnostic de l’impact sur l’environnement » en 2013.

150. Le Nicaragua réplique qu’il n’y avait pas de situation d’urgence
véritable (bona fide), soulignant que la route n’est pas située à proximité
du territoire litigieux, tel que défini dans l’ordonnance du 8 mars 2011, et
que l’état d’urgence a été déclaré plusieurs mois afprès le début des tra -
vaux de construction. Il n’existe par ailleurs, à son avis, aucune dérofga -

tion fondée sur l’urgence en ce qui a trait à l’obligation ifnternationale de
réaliser une évaluation de l’impact sur l’environnement. Il souligne que le
Costa Rica cherche, à tort, à se fonder sur une proclamation d’étaft d’ur -
gence faite en vertu de son droit interne pour justifier l’inexécuftion des
obligations que lui impose le droit international.

151. Enfin, le Nicaragua fait remarquer que les études de l’impact sur f
l’environnement que le Costa Rica a réalisées après avoir achevé l’essen -

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5 Ord 1088.indb 112 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 719

A. The Alleged Breach of Procedural Obligations

1. The alleged breach of the obligation to carry out an environmental

impact assessment

146. According to Nicaragua, Costa Rica breached its obligation
under general international law to assess the environmental impact of the
construction of the road before commencing it, particularly in view of tfhe
road’s length and location.
147. Costa Rica denies the allegation. It argues that the construction

of the road did not create a risk of significant transboundary harm
through the discharge of harmful substances into the San Juan River or
otherwise into Nicaraguan territory, and that there was no risk that thef
river would be materially affected by the relatively insignificant quantfities
of sediment coming from the road.

148. Costa Rica also maintains that it was exempted from the require -
ment to prepare an environmental impact assessment because of the state
of emergency created by Nicaragua’s occupation of Isla Portillos (sefe
paragraphs 63-64 above). First, Costa Rica argues that an emergency can
exempt a State from the requirement to conduct an environmental impact

assessment, either because international law contains a renvoi to domestic
law on this point, or because it includes an exemption for emergency sitfu -
ations. Secondly, Costa Rica submits that the construction of the road
was an appropriate response to the emergency situation because it would f
facilitate access to the police posts and remote communities located alofng

the right bank of the San Juan River, particularly in light of the real frisk
of a military confrontation with Nicaragua, which would require
Costa Rica to evacuate the area. Thus, Costa Rica claims that it could
proceed with its construction works without an environmental impact
assessment.

149. In any event, Costa Rica maintains that, even if it was required
under international law to conduct an environmental impact assessment
in this case, it fulfilled the obligation by carrying out a number of enfvir -
onmental impact studies, including an “Environmental Diagnostic
Assessment” in 2013.

150. In reply, Nicaragua argues that there was no bona fide emergency.
It states that the road is not located near the disputed territory, as dfefined
by the Court’s Order of 8 March 2011, and that the emergency was
declared several months after the beginning of the construction works.
Nicaragua further argues that there is no emergency exemption from the

international obligation to carry out an environmental impact assess -
ment. It points out that Costa Rica improperly seeks to rely on a declara-
tion of emergency made under its domestic law to justify its failure to
perform its international law obligations.

151. Finally, Nicaragua points out that the environmental impact
studies produced by Costa Rica after the bulk of the construction work

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tiel des travaux de construction ne sauraient constituer une évaluatifon
adéquate. En conséquence, il prie la Cour de déclarer que le Cofsta Rica

devrait s’abstenir de lancer tout nouveau projet dans la région safns avoir
procédé à une évaluation de l’impact sur l’environnemefnt appropriée.
152. Reprenant l’argumentation avancée par les Parties, la Cour
recherchera tout d’abord si le Costa Rica avait l’obligation, en droit inter-
national général, d’effectuer une évaluation de l’impact sur l’environne -

ment. Dans l’affirmative, elle examinera s’il était dispenséf de cette
obligation ou s’il y a satisfait en réalisant son «diagnostic de l’impact sur
l’environnement» et d’autres études.

*

153. La Cour rappelle (voir le paragraphe 104 ci-dessus) que, au titre
de l’obligation qui lui incombe de faire preuve de la diligence requifse en
vue de prévenir les dommages transfrontières importants, un Etat dfoit
vérifier s’il existe un risque de dommage transfrontière importfant avant
d’entreprendre une activité pouvant avoir un impact préjudiciable sur

l’environnement d’un autre Etat. Si tel est le cas, il lui faut efffectuer une
évaluation de l’impact sur l’environnement. L’obligation en question
incombe à l’Etat qui s’engage dans l’activité visée. Efn l’espèce, c’était
donc au Costa Rica, et non au Nicaragua, qu’il revenait d’apprécier,
avant le début des travaux de construction routière et sur la basef d’une

évaluation objective de l’ensemble des circonstances, l’existenfce d’un
risque de dommage transfrontière important.
154. Le conseil du Costa Rica a déclaré à l’audience qu’une évaluation
préliminaire du risque afférent au projet a été effectuéef au moment où a
été prise la décision de construire la route et que, compte tenfu de la nature
du projet et de son impact probable sur le fleuve, il a été concflu qu’aucun

risque de dommage important n’y était associé. A l’appui de fcette préten -
tion, le Costa Rica a souligné que le projet était d’ampleur refstreinte, qu’il
ne s’agissait manifestement pas d’une autoroute, que la route suivfait, sur
certains tronçons, le tracé de pistes existantes et que le seul rifsque tenait à
l’apport éventuel de sédiments provenant de la route dans un flfeuve pré -

sentant déjà une charge sédimentaire élevée.
La Cour relève que la réalisation d’une évaluation prélimfinaire du
risque créé par une activité est l’un des moyens par lesquelfs un Etat peut
vérifier si ladite activité comporte un risque de dommage transfrontière
important. Le Costa Rica n’a toutefois présenté aucune preuve qu’il avait

effectivement procédé à une telle évaluation préliminairef.
155. Pour rechercher si, à la fin de l’année 2010, la construction de la
route comportait un risque de dommage transfrontière important, la
Cour prendra en considération la nature et l’envergure du projet, fainsi
que le contexte dans lequel il devait être réalisé.
Premièrement, elle relève que, contrairement à l’affirmatiofn du

Costa Rica, le projet ne manquait pas d’ampleur. La route, qui s’étenfd
sur près de 160 kilomètres, longe le fleuve sur un tronçon de 108,2 kilo-

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had been completed do not constitute an adequate environmental impact
assessment. As a consequence, it asks the Court to declare that CostaRica

should not undertake any future development in the area without an
appropriate environmental impact assessment.
152. Following the lines of argument put forward by the Parties, the
Court will first examine whether Costa Rica was under an obligation to
carry out an environmental impact assessment under general interna -

tional law. If so, the Court will assess whether it was exempted from thfe
said obligation or whether it complied with that obligation by carrying f
out the Environmental Diagnostic Assessment and other studies.

*

153. The Court recalls (see paragraph 104 above) that a State’s obliga-
tion to exercise due diligence in preventing significant transboundary
harm requires that State to ascertain whether there is a risk of signififcant
transboundary harm prior to undertaking an activity having the potentialf
adversely to affect the environment of another State. If that is the casfe,

the State concerned must conduct an environmental impact assessment.
The obligation in question rests on the State pursuing the activity.
Accordingly, in the present case, it fell on Costa Rica, not on Nicaragua,
to assess the existence of a risk of significant transboundary harm priofr to
the construction of the road, on the basis of an objective evaluation off all

the relevant circumstances.

154. In the oral proceedings, counsel for Costa Rica stated that a pre -
liminary assessment of the risk posed by the road project was undertakenf
when the decision to build the road was made. According to Costa Rica,
this assessment took into account the nature of the project and its likefly

impact on the river, and concluded that the road posed no risk of signifif-
cant harm. In support of this claim, Costa Rica emphasized the modest
scale of the works, that the road was clearly not a highway, that some off
it was constructed on pre -existing tracks, and that the only possible risk
was the contribution of sediment by the road to a river that already carf -

ried a heavy sediment load.
The Court observes that to conduct a preliminary assessment of the
risk posed by an activity is one of the ways in which a State can ascertfain
whether the proposed activity carries a risk of significant transboundarfy
harm. However, Costa Rica has not adduced any evidence that it actually

carried out such a preliminary assessment.
155. In evaluating whether, as of the end of 2010, the construction of
the road posed a risk of significant transboundary harm, the Court will f
have regard to the nature and magnitude of the project and the context ifn
which it was to be carried out.
First, the Court notes that, contrary to Costa Rica’s submission,

the scale of the road project was substantial. The road, which is
nearly 160 km long, runs along the river for 108.2 km (see sketch -map

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5 Ord 1088.indb 115 19/10/16 12:01 721 certaines activitésf et construction d’unfe route (arrêt)

mètres (voir croquis n 2 ci-dessus), dont la moitié environ est de construc-

tion entièrement nouvelle.
Deuxièmement, la Cour constate que, étant donné l’emplacemenft projeté
de la route le long du San Juan, il était à prévoir que tout dofmmage causé
par celle-ci à l’environnement pourrait aisément toucher le fleuvfe et, par -
tant, le territoire du Nicaragua. Les éléments de preuve présentés à la Cour

révèlent que, sur environ la moitié du tronçon longeant le Sfan Juan, la
route passe à moins de 100 mètres de la rive; sur près de 18 kilomètres, elle
s’en approche à moins de 50 mètres et, par endroits, à moins de cinq mètres.
La grande proximité de la route par rapport au fleuve et sa construfction sur
des terrains souvent en pente risquaient d’augmenter le rejet de séfdiments

dans le San Juan. Il y a en outre lieu de prendre en considération, pour
apprécier le risque de sédimentation résultant de l’érosifon due à la route, le
fait que celle -ci traverserait, sur près du quart de son tracé, des régions
antérieurement boisées. Il doit être également tenu compte dfes possibilités
que se produisent dans la région des catastrophes naturelles causéfes par des

phénomènes tels que des ouragans, des tempêtes tropicales et defs séismes,
qui augmenteraient le risque de sédimentation liée à l’érfosion.
Troisièmement, il convient de prendre en compte les caractéristiqufes géo -
graphiques du bassin hydrographique où la route devait être constrfuite.
Celle-ci devait traverser une zone humide d’importance internationalef en

territoire costa-ricien et passer à proximité immédiate d’une autre zone
humide protégée, appelée Refugio de Vida Silvestre Río SanJuan, située en
territoire nicaraguayen. La présence de sites protégés sous le frégime de la
convention de Ramsar, qui témoigne de la fragilité particulièref de l’envi -
ronnement concerné, augmentait le risque de préjudice important. Lfe pri-n

cipal dommage susceptible de voir le jour tenait à l’importante séfdimentation
pouvant être causée par la route et aux risques en découlant pofur l’écologie
et la qualité des eaux du fleuve, ainsi qu’aux changements morphfologiques.
156. La Cour conclut que le projet de construction routière entrepris
par le Costa Rica comportait un risque de dommage transfrontière impor -

tant et que, en conséquence, le seuil d’application de l’obligaftion d’éva -
luer l’impact de ce projet sur l’environnement était atteint.

*

157. La Cour abordera à présent la question de savoir si le Costa Rica
était dispensé de son obligation d’évaluer l’impact du prfojet routier sur
l’environnement en raison d’une situation d’urgence. En premierf lieu, elle
rappelle qu’elle a déjà dit qu’«il revient à chaque Etat de déterminer, dans
le cadre de sa législation nationale ou du processus d’autorisation du pro -

jet, la teneur exacte de l’évaluation de l’impact sur l’envifronnement
requise dans chaque cas » compte tenu de différents facteurs (voir le para-
graphe 104 ci-dessus, citant Usines de pâte à papier sur le fleuve Uruguay
(Argentine c. Uruguay), arrêt, C.I.J. Recueil 2010 (I), p. 83, par. 205).
Elle observe que le renvoi au droit interne ainsi opéré ne concernfe pas la

question de savoir s’il y a lieu ou non de procéder à une évfaluation de

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5 Ord 1088.indb 116 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 721

No. 2 above). Approximately half of that stretch is completely new con -
struction.

Secondly, the Court notes that, because of the planned location of the
road along the San Juan River, any harm caused by the road to the sur -
rounding environment could easily affect the river, and therefore Nicaraf-
gua’s territory. The evidence before the Court shows that approximatefly
half of the stretch of road following the San Juan River is situated witfhin

100 metres of the river bank ; for nearly 18 km it is located within
50 metres of the river ; and in some stretches it comes within 5 metres of
the right bank of the river. The location of the road in such close proxfim -
ity to the river and the fact that it would often be built on slopes, rifsked
increasing the discharge of sediment into the river. Another relevant fafc-
tor in assessing the likelihood of sedimentation due to erosion from thef

road is that almost a quarter of the road was to be built in areas that fwere
previously forested. The possibility of natural disasters in the area cafused
by adverse events such as hurricanes, tropical storms and earthquakes,
which would increase the risk of sediment erosion, must equally be takenf
into consideration.

Thirdly, the geographic conditions of the river basin where the road
was to be situated must be taken into account. The road would pass
through a wetland of international importance in Costa Rican territory
and be located in close proximity to another protected wetland — the
Refugio de Vida Silvestre Río San Juan — situated in Nicaraguan terri -

tory. The presence of Ramsar protected sites heightens the risk of signiffi-
cant damage because it denotes that the receiving environment is
particularly sensitive. The principal harm that could arise was the possfi -
ble large deposition of sediment from the road, with resulting risks to fthe
ecology and water quality of the river, as well as morphological changesf.

156. In conclusion, the Court finds that the construction of the road by
Costa Rica carried a risk of significant transboundary harm. Therefore,
the threshold for triggering the obligation to evaluate the environmentafl
impact of the road project was met.

*

157. The Court now turns to the question of whether Costa Rica was
exempted from its obligation to evaluate the environmental impact of the
road project because of an emergency. First, the Court recalls its holding

that “it is for each State to determine in its domestic legislation ofr in the
authorization process for the project, the specific content of the envirfon -
mental impact assessment required in each case”, having regard to varfi -
ous factors (see paragraph 104 above, quoting Pulp Mills on the River
Uruguay (Argentina v. Uruguay), Judgment, I.C.J. Reports 2010 (I),
p. 83, para. 205). The Court observes that this reference to domestic law

does not relate to the question of whether an environmental impact
assessment should be undertaken. Thus, the fact that there may be an

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l’impact sur l’environnement. Il s’ensuit que l’existence, efn droit costa -
ricien, d’une dérogation fondée sur l’urgence n’aurait aufcune incidence

sur l’obligation d’effectuer une évaluation de l’impact sur fl’environne-
ment incombant au Costa Rica au titre du droit international.
158. En second lieu, indépendamment de la question de savoir si une
situation d’urgence est susceptible d’exonérer un Etat de son ofbligation, en
droit international, d’effectuer une évaluation de l’impact sur l’environne-

ment ou de lui permettre d’en différer l’exécution jusqu’fà la cessation de
l’urgence en question, la Cour estime que, dans les circonstances de l’es -
pèce, le Costa Rica n’a pas démontré l’existence d’une urgence justifiant de
construire la route sans entreprendre d’évaluation de l’impact fsur l’enviro -n
nement. En effet, l’exécution des travaux était prévue dèfs le départ pour
durer plusieurs années, ce qui s’est confirmé par la suite. De plus, lorsque le

Costa Rica a entrepris la construction de la route, la situation dont le terr-i
toire litigieux était le théâtre avait déjà été porftée devant la Cour, laquelle
a, peu de temps après, indiqué des mesures conservatoires. Si le Cfosta Rica
soutient que la route était destinée à faciliter l’évacuation de la portion de
territoire costa-ricien adjacente au fleuve SanJuan, la Cour constate que la

route ne donne accès qu’à une partie de cette région et ne pfouvait donc
constituer une réponse à l’urgence alléguée que dans une fmesure limitée.
Par ailleurs, le CostaRica n’a pas démontré l’existence d’une menace immi -
nente d’affrontement militaire dans les régions traversées par fla route.
Enfin, il est rappelé que le décret proclamant l’état d’ufrgence a été pris par

le Costa Rica le 21 février 2011, soit après le début des travaux routiers.
159. Ayant ainsi conclu que, dans les circonstances de l’espèce, aucunef
urgence ne justifiait la construction immédiate de la route, la Cour fn’a pas à
se prononcer sur la question de l’existence d’une dérogation, efn cas d’ur -
gence, à l’obligation d’effectuer une évaluation de l’impfact sur l’environn-e
ment dans les cas où il existe un risque de dommage transfrontièref important.

Ils’ensuit que le Costa Rica était tenu de procéder à une telle évalua -
tion avant d’amorcer les travaux de construction.

*

160. Abordant à présent la question de savoir si le Costa Rica s’est
conformé à son obligation d’effectuer une évaluation de l’impact sur l’en -
vironnement, la Cour constate qu’il a réalisé plusieurs étudfes, notamment
un plan de gestion environnementale relatif au projet routier en avril 2012,

un « diagnostic de l’impact sur l’environnement » en novembre 2013 et
une étude de suivi dudit diagnostic en janvier 2015. Ces différentes études
comportaient une évaluation des effets préjudiciables déjà cfausés par la
construction de la route sur l’environnement ainsi que des recommandaf -
tions pour la prise de mesures destinées à prévenir ou atténfuer ces effets.
161. La Cour a affirmé, dans l’arrêt qu’elle a rendu en l’afffaire relative

à des Usines de pâte à papier, que l’obligation de réaliser une évaluation de
l’impact sur l’environnement est une obligation continue et qu’fil y a lieu

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5 Ord 1088.indb 118 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 722

emergency exemption under Costa Rican law does not affect Costa Rica’s
obligation under international law to carry out an environmental impact

assessment.

158. Secondly, independently of the question whether or not an emer -
gency could exempt a State from its obligation under international law tfo
carry out an environmental impact assessment, or defer the execution of

this obligation until the emergency has ceased, the Court considers thatf,
in the circumstances of this case, Costa Rica has not shown the existence
of an emergency that justified constructing the road without undertakingf
an environmental impact assessment. In fact, completion of the project
was going to take, and is indeed taking, several years. In addition, whefn
Costa Rica embarked upon the construction of the road, the situation in

the disputed territory was before the Court, which shortly thereafter
issued provisional measures. Although Costa Rica maintains that the
construction of the road was meant to facilitate the evacuation of the afrea
of Costa Rican territory adjoining the San Juan River, the Court notes
that the road provides access to only part of that area and thus could

constitute a response to the alleged emergency only to a limited extent.f
Moreover, Costa Rica has not shown an imminent threat of military con -
frontation in the regions crossed by the road. Finally, the Court notes f
that the Executive Decree proclaiming an emergency was issued by
Costa Rica on 21 February 2011, after the works on the road had begun.

159. Having thus concluded that, in the circumstances of this case,
there was no emergency justifying the immediate construction of the roadf,
the Court does not need to decide whether there is an emergency exemp -
tion from the obligation to carry out an environmental impact assessmentf
in cases where there is a risk of significant transboundary harm.

It follows that Costa Rica was under an obligation to conduct an envir-
onmental impact assessment prior to commencement of the construction
works.

*

160. Turning now to the question of whether Costa Rica complied
with its obligation to carry out an environmental impact assessment, the
Court notes that Costa Rica produced several studies, including an Envir-
onmental Management Plan for the road in April 2012, an Environmen -

tal Diagnostic Assessment in November 2013, and a follow -up study
thereto in January 2015. These studies assessed the adverse effects that
had already been caused by the construction of the road on the environ -
ment and suggested steps to prevent or reduce them.

161. In its Judgment in the Pulp Mills case, the Court held that the

obligation to carry out an environmental impact assessment is a continu -
ous one, and that monitoring of the project’s effects on the environmfent

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d’assurer la surveillance des effets du projet sur l’environnement, au besoin
pendant toute la durée de vie de celui-ci (C.I.J. Recueil 2010 (I), p. 83-84,

par. 205). Cette obligation requiert toutefois que le risque de dommage
transfrontière important soit évalué ex ante; c’est pourquoi « une évalua-
tion de l’impact sur l’environnement doit être réalisée afvant la mise en
œuvre du projet » (ibid., p. 84, par. 205). En l’espèce, le Costa Rica avait
l’obligation de procéder à une telle évaluation avant d’efntreprendre la

construction de la route, afin de s’assurer que le projet serait conçfu et réa-
lisé de manière à réduire dans toute la mesure du possible lfe risque de
dommage transfrontière important. Or le « diagnostic de l’impact sur l’en-
vironnement » et les autres études effectuées par le Costa Rica ont consisté
dans une évaluation post hoc de l’impact environnemental des tronçons de
route déjà construits, et ne comportaient pas d’évaluation dfes risques de

dommage à venir. La Cour relève en outre que ce diagnostic a été établi
environ trois ans après la mise en chantier du projet.
162. Pour les raisons exposées ci -dessus, la Cour conclut que le
Costa Rica ne s’est pas acquitté de l’obligation qu’il avait, en vfertu du
droit international général, d’effectuer une évaluation de l’impact envi -

ronnemental de la construction de la route.

2.Allégation de violation de l’article 14 de la convention sur la diversité
biologique

163. Le Nicaragua avance que le Costa Rica était tenu d’effectuer une

évaluation de l’impact sur l’environnement au titre de l’artficle 14 de la
convention sur la diversité biologique. Le Costa Rica soutient pour sa
part que cette disposition concerne l’adoption de procédures approfpriées
à l’égard des projets susceptibles d’avoir un effet préjufdiciable important
sur la diversité biologique et qu’il a mis en place pareilles procfédures,

mais que, en tout état de cause, celles -ci ne s’appliquent pas à la construc -
tion de la route, puisque ce projet n’était pas susceptible d’afvoir un effet
préjudiciable important sur la diversité biologique.
164. La Cour rappelle que cette disposition énonce notamment ce qui
suit:

«Chaque Partie contractante, dans la mesure du possible et selon
qu’il conviendra: a) Adopte des procédures permettant d’exiger
l’évaluation des impacts sur l’environnement des projets qu’felle a

proposés et qui sont susceptibles de nuire sensiblement à la diverfsité
biologique en vue d’éviter et de réduire au minimum de tels efffets, et,
s’il y a lieu, permet au public de participer à ces procédures.f »

La Cour considère que la disposition en question ne crée pas d’fobligation
d’effectuer une évaluation de l’impact sur l’environnement afvant d’entre -
prendre une activité susceptible de nuire sensiblement à la diversfité biolo-
gique. Il n’a donc pas été établi que, en omettant d’éfvaluer l’impact sur

l’environnement de son projet routier, le Costa Rica a enfreint l’article 14
de la convention sur la diversité biologique.

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shall be undertaken, where necessary, throughout the life of the projectf
(I.C.J. Reports 2010 (I), pp. 83-84, para. 205). Nevertheless, the obliga -

tion to conduct an environmental impact assessment requires an ex ante
evaluation of the risk of significant transboundary harm, and thus “afn
environmental impact assessment must be conducted prior to the imple -
mentation of a project” (ibid., p. 83, para. 205). In the present case,
Costa Rica was under an obligation to carry out such an assessment prior

to commencing the construction of the road, to ensure that the design
and execution of the project would minimize the risk of significant tranfs-
boundary harm. In contrast, Costa Rica’s Environmental Diagnostic
Assessment and its other studies were post hoc assessments of the environ-
mental impact of the stretches of the road that had already been built. f
These studies did not evaluate the risk of future harm. The Court notes f

moreover that the Environmental Diagnostic Assessment was carried out
approximately three years into the road’s construction.
162. For the foregoing reasons, the Court concludes that Costa Rica
has not complied with its obligation under general international law to f
carry out an environmental impact assessment concerning the construc -

tion of the road.

2. The alleged breach of Article 14 of the Convention on Biological Diversity

163. Nicaragua submits that Costa Rica was required to carry out an

environmental impact assessment by Article 14 of the Convention on Bio-
logical Diversity. Costa Rica responds that the provision at issue con -
cerns the introduction of appropriate procedures with respect to projectfs
that are likely to have a significant adverse effect on biological diversity.
It claims that it had such procedures in place and that, in any event, tfhey

do not apply to the construction of the road, as it was not likely to hafve
a significant adverse effect on biological diversity.

164. The Court recalls that the provision reads, in relevant part :

“Each Contracting Party, as far as possible and as appropriate,
shall: (a) Introduce appropriate procedures requiring environmental
impact assessment of its proposed projects that are likely to have

significant adverse effects on biological diversity with a view to avoid -
ing or minimizing such effects and, where appropriate, allow for pub-
lic participation in such procedures.”

The Court considers that the provision at issue does not create an obligfa-
tion to carry out an environmental impact assessment before undertaking f
an activity that may have significant adverse effects on biological divefr -
sity. Therefore, it has not been established that Costa Rica breached Arti-

cle 14 of the Convention on Biological Diversity by failing to conduct an
environmental impact assessment for its road project.

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3. Allégation de violation d’une obligation de notification et de con▯sultation

165. Le Nicaragua allègue que le Costa Rica a manqué à l’obligation
de notification et de consultation qu’il avait envers lui au sujet des tra -

vaux de construction, obligation qui aurait selon lui trois sources, àf savoir
le droit international coutumier, le traité de 1858 et la convention de
Ramsar. La Cour examinera tour à tour chacun des moyens invoqués.

*

166. Le Nicaragua affirme que, ayant tout lieu de penser que son pro -
jet de construction routière risquait d’entraîner des dommages transfron -
tières importants, le Costa Rica aurait dû l’en informer et le consulter à
ce sujet, et ne pouvait se soustraire à cette obligation en raison d’fune

prétendue urgence.
167. Le Costa Rica soutient quant à lui que le critère du « risque d’im-
pact préjudiciable important » n’était pas rempli en l’espèce. Il fait valoir
que, bien qu’il l’ait invité à prendre part à des consultfations, le Nicaragua
n’en a rien fait. En tout état de cause, le Costa Rica estime que fle Nicara-
gua ne saurait invoquer l’obligation de notification, étant lui -même à

l’origine de la situation d’urgence à laquelle le Costa Rica a dû répondre
par la construction de la route.
168. La Cour réitère sa conclusion, selon laquelle, si l’évaluatifon de
l’impact sur l’environnement confirme l’existence d’un risque de dom -
mage transfrontière important, l’Etat d’origine est tenu, en vue de satis -

faire à son obligation de faire preuve de la diligence requise pour pfrévenir
les dommages transfrontières importants, d’informer et de consultefr de
bonne foi l’Etat susceptible d’être affecté, lorsque cela est nécessaire aux
fins de définir les mesures propres à prévenir ou réduire ce risque (voir le
paragraphe 104 ci-dessus). Toutefois, la question de l’obligation de noti -

fication et de consultation n’appelle pas un examen par la Cour en l’fes -
pèce, puisque la Cour a conclu que le Costa Rica ne s’est pas acquitté de
l’obligation qu’il avait, en droit international général, d’feffectuer une éva-
luation de l’impact sur l’environnement avant d’entreprendre laf construc-
tion de la route.

*

169. Le Nicaragua affirme par ailleurs que le traité de 1858 établit ufne
obligation de notification. Dans l’arrêt qu’elle a rendu en2009 en l’affaire du
Différend relatif à des droits de navigation, la Cour a conclu que le Nicaragua

avait l’obligation d’informer le Costa Rica de sa réglementation concernant
la navigation sur le fleuve. Le Nicaragua fait valoir que, étant dofnné que la
construction de la route a une incidence sur ses propres droits de navigfation,
ce même raisonnement vaut afortiori pour la présente affaire.
170. Le Costa Rica soutient pour sa part que le Nicaragua est malvenu

d’invoquer le traité de 1858, puisque celui-ci ne lui impose aucune obliga -

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3. The alleged breach of an obligation to notify and consult

165. Nicaragua contends that Costa Rica breached its obligation to
notify, and consult with, Nicaragua in relation to the construction workfs.

Nicaragua founds the existence of such obligation on three grounds, namely,
customary international law, the 1858 Treaty, and the Ramsar Con -
vention. The Court will examine each of Nicaragua’s arguments in turn.

*

166. In Nicaragua’s view, Costa Rica should have notified it of the
road project and should have consulted with it, as Costa Rica had every
reason to believe that the construction of the road risked causing signifi -
cant transboundary harm. According to Nicaragua, the alleged emer -

gency did not exempt Costa Rica from this obligation.
167. For Costa Rica, the relevant threshold of “risk of significant
adverse impact” was not met in this case. Moreover, Costa Rica claims to
have invited Nicaragua to engage in consultations, but Nicaragua did notf
do so. In any event, according to Costa Rica, Nicaragua is prevented
from relying on the obligation to notify since it has itself created thef

emergency to which Costa Rica had to respond by constructing the road.

168. The Court reiterates its conclusion that, if the environmental
impact assessment confirms that there is a risk of significant transbounfd -
ary harm, a State planning an activity that carries such a risk is requifred,

in order to fulfil its obligation to exercise due diligence in preventinfg sig -
nificant transboundary harm, to notify, and consult with, the potentiallfy
affected State in good faith, where that is necessary to determine the
appropriate measures to prevent or mitigate that risk (see paragraph 104
above). However, the duty to notify and consult does not call for exam -

ination by the Court in the present case, since the Court has established
that Costa Rica has not complied with its obligation under general inter -
national law to perform an environmental impact assessment prior to the f
construction of the road.

*

169. Nicaragua further asserts the existence of an obligation to notify
under the 1858 Treaty. In its 2009 Judgment in the Navigational Rights
case, the Court held that Nicaragua has an obligation to notify CostaRica

of its regulations concerning navigation on the river. According to Nicaf-
ragua, since the construction of the road affects Nicaragua’s navigatfional
rights, the same reasoning applies a fortiori in this case.

170. For Costa Rica, Nicaragua’s reference to the 1858 Treaty is mis-

placed, since the Treaty does not impose on Costa Rica an obligation to

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5 Ord 1088.indb 123 19/10/16 12:01 725 certaines activitésf et construction d’unfe route (arrêt)

tion de notification envers son voisin lorsqu’il entreprend des travafux
d’infrastructure sur son propre territoire.

171. La Cour rappelle que, dans son arrêt de 2009, elle a dit que l’obli-
gation de notification dont le Nicaragua était, au titre du traité de 1858,
redevable au Costa Rica découlait, entre autres, des droits de navigation
que ce dernier détient sur le fleuve San Juan, situé en territoire nicara -
guayen (Différend relatif à des droits de navigation et des droits connexe▯s

(Costa Rica c. Nicaragua), arrêt, C.I.J. Recueil 2009, p. 251-252,
par. 94-97). Le Nicaragua ne tenant quant à lui du traité de 1858 aucufn
droit sur le territoire costa-ricien, où la route est construite, il fn’en résulte
aucune obligation pour le Costa Rica de notifier au Nicaragua les mesurefs
prises sur son territoire. La Cour conclut que le traité de 1858 ne ffaisait
peser sur le Costa Rica aucune obligation de notification envers le Nica -

ragua en ce qui concerne la construction de la route.

*

172. Enfin, le Nicaragua invoque le paragraphe 2 de l’article3 et l’ar-

ticle 5 de la convention de Ramsar (voir les paragraphes 109-110
ci-dessus), qui imposent selon lui aux Etats parties une obligation de fnot-i
fication et de consultation. De l’avis de la Cour, le Nicaragua n’fa pas
démontré que le projet de construction routière a modifié ouf risquait de
modifier les caractéristiques écologiques de la zone humide situéfe sur son

territoire.Qui plus est et contrairement aux affirmations du Nicaragua, le
Costa Rica a, le 28 février 2012, informé le Secrétariat de la convention de
Ramsar qu’une section de la route traversait la zone humide Humedal
Caribe Noreste. La Cour conclut en conséquence que le Nicaragua n’a
pas prouvé que le Costa Rica a enfreint les dispositions du paragraphe 2
de l’article 3 de la convention de Ramsar. S’agissant de l’article 5 de

celle-ci, la Cour est d’avis que cette disposition n’impose au Costa Rica
aucune obligation de consultation envers le Nicaragua au sujet d’un pfro -
jet particulier qu’il entreprend, comme, en l’occurrence, la construction
de la route (voir également le paragraphe 110 ci-dessus).

*

173. En conclusion, la Cour constate que le Costa Rica a manqué à
son obligation d’évaluer l’impact environnemental de la construfction de
la route. Il demeure tenu de procéder à une évaluation approprifée relati -
vement à tous nouveaux travaux qu’il envisagerait d’exécuterf sur la route

ou dans la zone adjacente au fleuve San Juan et qui présenteraient fun
risque de dommage transfrontière important. Le Costa Rica admet
lui-même être tenu à pareille obligation. Il n’y a pas lieu de sfupposer que,
lorsqu’il entreprendra de nouveaux travaux dans ce secteur, notammentf
dans le cadre de la construction de la route, il ne tiendra pas compte dfes

motifs et des conclusions énoncés dans le présent arrêt. La Cour relève
par ailleurs que le Nicaragua s’est, à l’audience, engagé àf coopérer avec le

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notify Nicaragua if Costa Rica undertakes infrastructure works on its
own territory.

171. The Court recalls its finding in the 2009 Judgment that Nicara -
gua’s obligation to notify Costa Rica under the 1858 Treaty arises,
amongst other factors, by virtue of Costa Rica’s rights of navigation
on the river, which is part of Nicaragua’s territory (Dispute regarding
Navigational and Related Rights (Costa Rica v. Nicaragua), Judgment,

I.C.J. Reports 2009, pp. 251-252, paras. 94-97). In contrast, the
1858 Treaty does not grant Nicaragua any rights on Costa Rica’s terri-
tory, where the road is located. Therefore, no obligation to notify Nicafra -
gua with respect to measures undertaken on Costa Rica’s territory arises.
The Court concludes that the 1858 Treaty did not impose on Costa Rica
an obligation to notify Nicaragua of the construction of the road.

*

172. Lastly, Nicaragua relies on Article 3, paragraph 2, and on Arti -

cle 5 of the Ramsar Convention (see paragraphs 109-110 above) as impos-
ing an obligation of notification and consultation upon the Contracting f
Parties. In the Court’s view, Nicaragua has not shown that, by constrfuct-
ing the road, Costa Rica has changed or was likely to change the eco-
logical character of the wetland situated in its territory. Moreover,

contrary to Nicaragua’s contention, on 28 February 2012 Costa Rica
notified the Ramsar Secretariat about the stretch of the road that passefs
through the Humedal Caribe Noreste. Therefore, the Court concludes that
Nicaragua has not shown that Costa Rica breached Article 3, para -
graph 2, of the Ramsar Convention. As regards Article 5 of the Ramsar
Convention, the Court finds that this provision creates no obligation for

Costa Rica to consult with Nicaragua concerning a particular project it is
undertaking, in this case the construction of the road (see also para -
graph 110 above).

*

173. In conclusion, the Court finds that Costa Rica failed to comply
with its obligation to evaluate the environmental impact of the construcf-
tion of the road. Costa Rica remains under an obligation to prepare an
appropriate environmental impact assessment for any further works on

the road or in the area adjoining the San Juan River, should they carry a
risk of significant transboundary harm. Costa Rica accepts that it is under
such an obligation. There is no reason to suppose that it will not take f
note of the reasoning and conclusions in this Judgment as it conducts anfy
future development in the area, including further construction works on f

the road. The Court also notes Nicaragua’s commitment, made in the
course of the oral proceedings, that it will co -operate with Costa Rica in

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Costa Rica pour l’évaluation de l’impact de tels travaux sur le fleuve. Elle
considère à cet égard que, si les circonstances l’exigent, lfe Costa Rica

devra consulter de bonne foi le Nicaragua, qui a souveraineté sur le fleuve
San Juan, en vue de définir les mesures propres à prévenir la survenance
de dommages transfrontières importants ou à en réduire le risqufe.

B. Allégations de violation d’obligations de fond

174. La Cour examinera à présent les allégations concernant la violaf -
tion, par le Costa Rica, des obligations de fond lui incombant au titre du
droit international coutumier et des conventions internationales appli -
cables. Le Nicaragua soutient en particulier que la construction de la
route a porté préjudice au fleuve San Juan, qui, conformément au traité

de 1858, relève de sa souveraineté. Ainsi, le Costa Rica a selon lui man -
qué à l’obligation que lui faisait le droit international coutufmier de ne pas
lui causer de dommages transfrontières importants, à celle de respfecter
son intégrité territoriale et à des obligations conventionnellefs ayant trait
à la protection de l’environnement.

175. Au cours des quatre années écoulées, les Parties ont présentfé à la
Cour, à l’appui de leurs prétentions respectives, un volume confsidérable
d’éléments factuels et scientifiques. Ont également étéf soumis de nom -
breux rapports et études établis à leur demande par des expertsf et consul-
tants sur des sujets tels que les normes techniques de construction routfière,

la morphologie fluviale, les niveaux de sédimentation du fleuve San Juan
ainsi que leurs causes et leurs effets, l’impact écologique de la fconstruc -
tion de la route et l’état d’avancement des mesures d’attéfnuation mises en
œuvre par le Costa Rica. Certains de ces spécialistes ont par ailleurs été
entendus par la Cour en qualité d’experts sous le régime des arfticles 57

et 64 du Règlement de celle-ci.
176. Il incombe à la Cour, au terme d’un examen attentif de l’ensembfle
des éléments versés au dossier, d’en apprécier la valeur probante, de déter-
miner quels faits sont à prendre en considération et d’en tirerf les conclu -
sions qui s’imposent. Ainsi, fidèle à sa pratique, la Cour se pfrononcera sur
les faits, en se fondant sur l’ensemble des éléments de preuve fqui lui ont été

présentés, puis appliquera les règles du droit international àf ceux qu’elle
aura jugés avérés (Usines de pâte à papier sur le fleuve Uruguay (Argentine
c. Uruguay), arrêt, C.I.J. Recueil 2010 (I), p. 72, par. 168).

1. Allégation de violation de l’obligation de ne pas causer de dommag▯e
transfrontière important au Nicaragua

177. Le Nicaragua soutient que la construction de la route a entraîné lfe
rejet dans le fleuve San Juan de quantités considérables de sédiments, en
raison notamment de l’érosion importante due à l’inobservation, de la part

du Costa Rica, de principes élémentaires d’ingénierie. Ce dernier se fserait
ainsi livré à une déforestation massive dans les secteurs adjacfents au fleuve

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5 Ord 1088.indb 126 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 726

assessing the impact of such works on the river. In this connection, thef
Court considers that, if the circumstances so require, Costa Rica will have

to consult in good faith with Nicaragua, which is sovereign over the Sanf
Juan River, to determine the appropriate measures to prevent significantf
transboundary harm or minimize the risk thereof.

B. Alleged Breaches of Substantive Obligations

174. The Court now turns to the examination of the alleged violations
by Costa Rica of its substantive obligations under customary interna -
tional law and the applicable international conventions. In particular, f
Nicaragua claims that the construction of the road caused damage to the f
San Juan River, which is under Nicaragua’s sovereignty according to the

1858 Treaty. Thus, in Nicaragua’s view, Costa Rica breached the obliga-
tion under customary international law not to cause significant trans -
boundary harm to Nicaragua, the obligation to respect the territorial
integrity of Nicaragua and treaty obligations regarding the protection off
the environment.

175. Over the past four years, the Parties have presented to the Court
a vast amount of factual and scientific material in support of their resfpec-
tive contentions. They have also submitted numerous reports and studies f
prepared by experts and consultants commissioned by each of them on
questions such as technical standards for road construction ; river mor -

phology ; sedimentation levels in the San Juan River, their causes and
effects; the ecological impact of the construction of the road ; and the
status of remediation works carried out by Costa Rica. Some of these
specialists have also appeared before the Court to give evidence in theifr
capacity as experts pursuant to Articles 57 and 64 of the Rules of Court.

176. It is the duty of the Court, after having given careful consider -
ation to all the evidence in the record, to assess its probative value, fto
determine which facts must be considered relevant, and to draw conclu -
sions from them as appropriate. In keeping with this practice, the Courtf
will make its own determination of the facts, on the basis of the totalifty

of the evidence presented to it, and it will then apply the relevant rulfes of
international law to those facts which it has found to be established (fPulp
Mills on the River Uruguay (Argentina v. Uruguay), Judgment, I.C.J.
Reports 2010 (I), p. 72, para. 168).

1.The alleged breach of the obligation not to cause significant transboundary
harm to Nicaragua

177. Nicaragua claims that the construction works resulted in the
dumping of large quantities of sediment into the San Juan River, in par-
ticular because Costa Rica’s disregard of basic engineering principles led

to significant erosion. For example, Costa Rica carried out extensive
deforestation in areas adjacent to the river and earthmoving activities

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5 Ord 1088.indb 127 19/10/16 12:01 727 certaines activitésf et construction d’unfe route (arrêt)

et à des activités de terrassement qui auraient entraîné la fformation de

talus de déblai et de remblai instables à proximité du cours d’feau. De plus,
ceux qui ont travaillé à la construction de la route auraient laisfsé des amas
de terre exposés aux précipitations et omis d’installer les sysftèmes de dra-i
nage et ponceaux voulus afin de limiter l’érosion. En outre, le Nifcaragua
avance que, sur le tronçon qui longe le San Juan, la route a étéf construite

trop près de celui-ci — elle se trouve, sur près de la moitié de son parcours,
à moins de 100 mètres du rivage, dont elle s’approche, par endroits, à
moins de 5 mètres — ou sur des pentes raides, ce qui augmente le déverse -
ment de sédiments dans le fleuve. Selon son expert principal, l’férosion est
particulièrement grave sur le tronçon de 41,6 kilomètres marqué par les
o
pentes les plus raides, lequel est situé entre un point appelé «borne n II»
(le point occidental à partir duquel la rive droite du San Juan forme la
frontière avec le Nicaragua) et BocaSan Carlos (au confluent du San Juan
et de la rivière San Carlos ; voir croquis no2 ci-dessus).
178. Selon le Nicaragua, le rejet de ces quantités importantes de sédi -

ments a entraîné la hausse des concentrations sédimentaires défjà anorma-
lement élevées du San Juan. Il affirme que le seul fait de cette augmentation
a causé des dommages au fleuve, les sédiments étant des pollufants, et que
ladite augmentation a eu un nombre de conséquences préjudiciables.f Pre-
mièrement, la morphologie du fleuve s’en serait trouvée modififée, du fait

que les sédiments issus de l’érosion de la route s’accumulerfaient en grandes
quantités sur le lit du San Juan inférieur, ce qui accentuerait les difficultés
de navigation dans cette partie du fleuve et obligerait le Nicaragua àf mul -
tiplier ses opérations de dragage pour rétablir la navigabilité du chenal.
Ces sédiments auraient par ailleurs formé, le long de la rive costfa-ricienne,

de larges deltas faisant obstacle à la navigation. Deuxièmement, lfe Nicar-a
gua soutient que les sédiments qui proviennent de l’érosion de fla route ont
porté atteinte à la qualité de l’eau et à l’écosystème du fleuve. Troisième -
ment, il allègue que la construction de la route a eu un effet préfjudiciable
sur le tourisme et sur la santé des populations riveraines. Il avancef en

outre que d’autres dommages sont à prévoir puisque le Costa Rica conti-
nue à méconnaître les normes applicables en la matière et àf ne prendre
aucune des mesures correctives appropriées. Il ajoute que des risques sup-
plémentaires existent en raison du déversement possible de matièfres
toxiques dans le fleuve, de l’aménagement de la rive costa -ricienne de

celui-ci et des probabilités de catastrophes naturelles causées par des févé-
nements tels que des ouragans, des tempêtes tropicales ou des séisfmes.
179. Le Costa Rica avance pour sa part que la construction de la route
n’a causé aucun dommage au Nicaragua. Il considère que l’éfrosion est un
processus naturel et que les sédiments ne sont pas des polluants. Le fNica-

ragua n’a selon lui fourni aucune preuve d’un dommage réel et efncore
moins d’un dommage important qui ait été causé au fleuve. fLe Costa Rica
soutient en outre que la proportion de sédiments provenant de la routfe
est faible en comparaison de la charge sédimentaire déjà préfsente dans le
fleuve. Il rappelle par ailleurs que, depuis 2012, il effectue, sur les talus et

points de passage de cours d’eau, des travaux visant à atténuerf l’érosion

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5 Ord 1088.indb 128 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 727

that led to the creation of unstable cuts and fills in the river’s prfoximity.
Moreover, the road builders left piles of earth exposed to rainfall and f

failed to construct proper drainage systems and stream crossings so as tfo
avoid erosion. Furthermore, Nicaragua maintains that the stretch of roadf
along the San Juan River is situated too close to the river — nearly half
of it was built within 100 metres of the river, and parts of it even within
5 metres of the river bank — or on steep slopes, thereby increasing the

delivery of sediment to the river. Nicaragua’s main expert opined that
erosion is particularly severe in the 41.6 km stretch of the road containing
the steepest sections, situated between a point denominated “Marker II”
(the western point from which the right bank of the San Juan marks the
boundary with Nicaragua) and Boca San Carlos (at the junction of the
San Juan and San Carlos Rivers ; see sketch-map No. 2 above).

178. According to Nicaragua, the delivery of these large quantities of
sediment to the San Juan River caused an increase in sediment concentra-
tions in the river, which are already unnaturally elevated. It argues thfat

this increase, in and of itself, produced harm to the river, as sedimentf is a
pollutant, and that it had a number of adverse effects. First, it broughft
about changes in the river morphology, as large quantities of the sedi -
ment eroded from the road accumulated on the bed of the Lower
San Juan, thereby exacerbating the problems for navigation in this stretch

of the river and rendering additional dredging necessary to restore the f
navigability of the channel. Moreover, sediment eroded from the road
created large deltas along the Costa Rican bank of the river that obstruct
navigation. Secondly, Nicaragua argues that sediment eroded from the
road caused harm to the river’s water quality and ecosystem. Thirdly,f
Nicaragua alleges that the construction of the road has had an adverse

impact on tourism and the health of the river’s riparian communities.f In
addition, Nicaragua maintains that Costa Rica’s continuing failure to
comply with road construction standards exposes Nicaragua to future
harm, and that Costa Rica has failed to take appropriate remediation
measures. Nicaragua further contends that additional risks derive from

the possibility of spills of toxic materials into the river, the furtherf devel
opment of the Costa Rican bank of the river and the likelihood of natural
disasters caused by adverse events such as hurricanes, tropical storms afnd
earthquakes.
179. For its part, Costa Rica argues that the construction of the road

has not caused any harm to Nicaragua. According to Costa Rica, erosion
is a natural process and sediment is not a pollutant. It contends that
Nicaragua has not adduced any evidence of actual harm to the river, let f
alone significant harm. In addition, Costa Rica argues that the road’s
sediment contribution is tiny compared to the river’s existing sediment
load. It also recalls that, since 2012, it has carried out remediation wforks

to mitigate erosion at slopes and watercourse crossings (such as slope -
terracing; digging drainage channels ; installing cross -drains on the road ;

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5 Ord 1088.indb 129 19/10/16 12:01 728 certaines activitésf et construction d’unfe route (arrêt)

(aménagement de talus en terrasses, creusement de canaux de drainagef,
pose de canalisations d’écoulement transversales sur la route, insftallation

de trappes à sédiments et remplacement des passerelles en rondins fpar des
ponts modulaires), afin de réduire encore davantage la quantité de sédi -
ments qui pénètrent dans le fleuve San Juan.
180. Aux fins de se prononcer sur les allégations du Nicaragua, la Cour
commencera par examiner les moyens des Parties concernant l’apport

sédimentaire au fleuve attribuable à la route, puis elle rechercfhera si ces
sédiments ont causé des dommages importants au Nicaragua.

a) Apport sédimentaire au fleuve attribuable à la route

181. Si les Parties conviennent que l’érosion de la route entraîne lfe rejet
de sédiments dans le fleuve, leurs vues divergent considérablement sur le
volume réel en cause.

182. Le Nicaragua fait valoir que la méthode la plus directe et la plus
fiable de quantifier l’apport sédimentaire total provenant de la rfoute
consiste à estimer les quantités de sédiments qui pénètrefnt dans le fleuve
en chacun des points touchés par l’érosion le long de la route.f Sur la base
des estimations effectuées par son expert principal, il avance que lef volume

de sédiments déversés dans le fleuve provenant de la route sef situe chaque
année entre 190 000 et 250 000 tonnes, cette estimation incluant l’apport
des voies secondaires qui relient la route aux zones situées à l’fintérieur des
terres. Il ajoute que les quantités de sédiments dans le fleuve provenant de
la construction de la route seraient au moins dix fois plus grandes en cas

de tempête tropicale ou d’ouragan.
183. Le Costa Rica conteste les estimations avancées par le Nicaragua
quant au volume des sédiments provenant de la route. S’appuyant sufr les
conclusions de son expert principal, il avance en particulier que les exfperts
du Nicaragua ont surestimé la superficie des zones touchées par l’férosion,

qu’ils n’ont pas pu mesurer directement puisque la route se trouvef en
territoire costa-ricien. Il ajoute que les estimations du Nicaragua sont
artificiellement gonflées par la prise en considération des voies secon -
daires, qui ne causent le rejet d’aucune quantité appréciable dfe sédiments
dans le fleuve San Juan. Selon lui, l’apport sédimentaire attribuable à la

route chaque année est d’environ 75 000 tonnes, chiffre qui serait lui-même
largement surestimé, étant donné qu’il ne tient pas compte dfes effets des
travaux d’atténuation récemment effectués. Enfin, il soutienft que les
experts du Nicaragua ont exagéré le risque d’épisodes pluviofmétriques
exceptionnels et l’impact que pourrait avoir un ouragan ou une tempêfte

tropicale sur les charges sédimentaires dans le fleuve.
184. Le Costa Rica souligne par ailleurs que la méthode la plus directe
et la plus fiable de mesurer l’impact de la route sur les concentratifons
sédimentaires du San Juan eût été que le Nicaragua, qui a souveraineté
sur le fleuve, y mette en place un programme de prélèvements ; or il n’a

fourni aucune mesure de charge sédimentaire ou de débit le concernfant.
Les seules données empiriques qui ont été présentées àf la Cour sont deux

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5 Ord 1088.indb 130 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 728

constructing sediment traps ; and replacing log bridges with modular
bridges), with a view to further reducing the quantity of sediment fromf

the road that reaches the San Juan River.

180. In order to pronounce on Nicaragua’s allegations, the Court will
first address the Parties’ arguments on the contribution of sediment ffrom

the road to the river ; then it will examine whether the road -derived sedi-
ment caused significant harm to Nicaragua.

(a) The contribution of sediment from the road to the river

181. The Parties agree that sediment eroded from the road is delivered
to the river, but disagree considerably as to the actual volume.

182. Nicaragua argues that the most direct and reliable method to
assess the total amount of sediment contributed from the road is to estif -
mate the volume of sediment entering the river from all the sites along the
road that are subject to erosion. It submits, based on its main expert’fs
estimates, that the total road-derived sediment reaching the river amounts

to approximately 190,000 to 250,000 tonnes per year, including sediment
eroded from the access roads that connect the road to inland areas. Nica -
ragua further submits that the volume of sediment in the river due to thfe
construction of the road would increase by a factor of at least ten durifng
a tropical storm or a hurricane.

183. Costa Rica challenges the estimates of road -derived sediment put
forward by Nicaragua. In particular, it argues, relying on its main expefrt’s
evidence, that Nicaragua’s experts over -estimated the areas subject to
erosion, which they could not measure directly because the road is in

Costa Rica’s territory. It adds that Nicaragua’s estimates are inflatefd by
the inclusion of access roads, which do not contribute any appreciable
quantities of sediment to the San Juan River. According to Costa Rica,
the sediment contribution from the road is approximately 75,000 tonnes
per year. In Costa Rica’s view, even this figure is a significant over -

estimate because it does not take into account the effects of mitigationf
works recently carried out. Finally, Costa Rica argues that Nicaragua’s
experts have overstated the risk of unprecedented rainfall and the impacft
on sediment loads in the river as a result of hurricanes or tropical stofrms.

184. Costa Rica further points out that the most direct and reliable
method for measuring the road’s impact on sediment concentrations in f
the San Juan River would have been for Nicaragua, which is sovereign
over the river, to carry out a sampling programme. Yet Nicaragua has

not provided measurements of sedimentation and flow levels in the river.
The only empirical data before the Court are two reports of the Nicara -

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5 Ord 1088.indb 131 19/10/16 12:01 729 certaines activitésf et construction d’unfe route (arrêt)

rapports de l’institut nicaraguayen d’études territoriales (INfETER), qui
comportent des mesures du débit et des concentrations de sédimentsf en

suspension prises en différents points du fleuve en 2011 et en 2012. Selon
le Costa Rica, aucune de ces mesures ne montre quelque impact attri -
buable à la route.
185. Le Nicaragua répond qu’un programme de prélèvement n’aurafit
pas permis d’apprécier l’impact des sédiments généréfs par la route puisque

l’on ne connaît pas la charge sédimentaire qui était celle dfu San Juan
avant le début des travaux de construction routière.
186. La Cour observe que le déversement dans le fleuve de sédiments
produits par l’érosion de la route n’est pas contesté. S’fagissant du volume
total de ces sédiments, elle fait remarquer que les éléments de preuve dont

elle dispose sont fondés sur la modélisation et les estimations réalisées par
les experts des deux Parties. La Cour relève par ailleurs qu’il exfiste entre
les experts d’importantes divergences de vues sur certaines donnéefs fon -
damentales telles que la superficie des zones touchées par l’érfosion et les
taux d’érosion qu’il convient d’appliquer à chacune d’felles, divergences

qui les ont conduits à des conclusions différentes quant au volumef total
des sédiments produits par la route. La Cour n’estime pas nécesfsaire de
procéder à un examen approfondi de la valeur scientifique et technique
des différentes estimations avancées par les experts des Parties. fIl sera
simplement constaté que la quantité de sédiments dans le fleuve prove-
nant de la construction de la route représente tout au plus 2 % de la

charge sédimentaire totale du fleuve, selon les évaluations du Cfosta Rica
fondées sur les conclusions des experts du Nicaragua, et non contestéfes
par ce dernier (voir les paragraphes 182-183 ci-dessus et 188-191 ci-après).
La Cour reviendra plus loin sur ce point (voir le paragraphe 194), après
avoir examiné les autres moyens présentés par les Parties.

b) Question de savoir si les sédiments produits par la route ont causé des
dommages importants au Nicaragua

187. La question centrale à trancher par la Cour est celle de savoir si laf
construction de la route par le CostaRica a causé des dommages importants
au Nicaragua. Pour y répondre, la Cour commencera par rechercher si lfe
seul fait que la quantité totale de sédiments dans le fleuve a afugmenté par

suite de la construction de la route a causé des dommages importants fau
Nicaragua. Elle examinera ensuite si l’augmentation en cause a portéf atteinte
en particulier à la morphologie du fleuve, à la navigation et au programme
de dragage du Nicaragua, à la qualité de l’eau et à l’éfcosystème aquatique,
ou si elle a causé quelque autre dommage pouvant être important.

i) Les dommages qui auraient résulté de la hausse des concentrations ▯

sédimentaires dans le fleuve
188. Le Nicaragua avance que, indépendamment de son chiffrage

exact, le volume (la quantité totale) de sédiments produits par fl’érosion de
la route a pollué le fleuve, causant ainsi des dommages importants fau

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5 Ord 1088.indb 132 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 729

guan Institute of Territorial Studies (INETER), which contain measure -
ments of flow rates and suspended sediment concentrations taken at

various locations along the San Juan River in 2011 and 2012. Costa Rica
argues that neither set of measurements shows any impact from the road.

185. Nicaragua replies that a sampling programme would not have
been of assistance to assess the impact of the road -derived sediment

because the baseline sediment load of the San Juan prior to the construc-
tion of the road is unknown.
186. The Court notes that it is not contested that sediment eroded
from the road is delivered to the river. As regards the total volume of f
sediment contributed by the road, the Court observes that the evidence

before it is based on modelling and estimates by experts appointed by thfe
Parties. The Court further observes that there is considerable disagree -
ment amongst the experts on key data such as the areas subject to erosion
and the appropriate erosion rates, which led them to reach different conf-
clusions as to the total amount of sediment contributed by the road. The

Court sees no need to go into a detailed examination of the scientific and
technical validity of the different estimates put forward by the Partiesf’
experts. Suffice it to note here that the amount of sediment in the rivfer
due to the construction of the road represents at most 2 per cent of the
river’s total load, according to Costa Rica’s calculations based on the fig-
ures provided by Nicaragua’s experts and uncontested by the latter (fsee

paragraphs 182-183 above and 188-191 below). The Court will come back
to this point below (see paragraph 194), after considering further argu -
ments by the Parties.

(b) Whether the road‑derived sediment caused significant harm to
Nicaragua

187. The core question before the Court is whether the construction of
the road by Costa Rica has caused significant harm to Nicaragua. The
Court will begin its analysis by considering whether the fact that the tfotal
amount of sediment in the river was increased as a result of the construfc-

tion of the road, in and of itself, caused significant harm to Nicaraguaf.
The Court will then examine whether such increase in sediment concen -
trations caused harm in particular to the river’s morphology, navigatfion
and Nicaragua’s dredging programme ; the water quality and the aquatic
ecosystem; or whether it caused any other harm that may be significant.

(i) Alleged harm caused by increased sediment concentrations in the

river
188. Nicaragua contends that the volume (absolute quantity) of sedi -

ment eroded from the road, irrespective of its precise amount, polluted f
the river thereby causing significant harm to Nicaragua. In Nicaragua’fs

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Nicaragua. L’impact de l’apport provenant de la route doit selon lfui être
apprécié au regard de la charge sédimentaire élevée du flfeuve San Juan

qui résulterait des opérations de déboisement et des mauvaises fpratiques
d’utilisation des sols menées par le Costa Rica. L’un des experts du Nica-
ragua a estimé à environ 13 700 000 tonnes par an la charge sédimentaire
actuelle du fleuve. Dans ce contexte, le Nicaragua soutient qu’il efxiste
pour le fleuve une charge sédimentaire critique au -delà de laquelle tout

apport en provenance de la route est forcément nocif.
189. Le Costa Rica répond que le Nicaragua n’a pas démontré que l’on
puisse attribuer au fleuve San Juan une charge sédimentaire critique qui
aurait été dépassée. Selon lui, la question dont est saisie fla Cour est celle de
savoir si l’impact relatif des sédiments issus de la route sur la fcharge totale
du fleuve est à l’origine de dommages importants. La réponse,f de son point

de vue, est négative. Il fait valoir que le Sanan présente une charge sédi -
mentaire naturellement élevée, laquelle est imputable aux conditiofns géo-lo
giques de la région, notamment aux séismes et éruptions volcanifques qui
secouent le bassin du fleuve et de ses affluents. L’apport sédimentaire de la
route serait négligeable par rapport à la charge sédimentaire tfotale du

fleuve (estimée par le Costa Rica à 12 678 000 tonnes par an), dont il ne
représenterait tout au plus que 0,6 %. Il serait par ailleurs imperceptible
compte tenu de la grande variabilité des quantités de sédimentsf provenant
d’autres sources. Le Costa Rica ajoute que, même si l’on retenait l’estima-
tion du Nicaragua, l’apport sédimentaire provenant de la constructfion de la

route représenterait une faible proportion, de l’ordre de 1 à 2%, de la
charge totale transportée par le San Juan. De son point de vue, il s’agit
d’une quantité trop faible pour avoir un impact important.
190. S’appuyant sur le commentaire afférent au projet d’articles de la
Commission du droit international sur la prévention des dommages tranfs -
frontières résultant d’activités dangereuses, le Nicaragua afjoute qu’il suf-

fit, pour qu’un dommage important soit constitué, que quelque effeft
préjudiciable imputable à la construction de la route sur le flefuve Sanuan
soit susceptible d’être mesuré. Ainsi, la quantité de sédfiments dans le
fleuve provenant de la construction de la route étant mesurable, comme
en témoignent les estimations avancées par les experts des deux Pafrties, il

soutient que les dommages causés sont importants.
191. Le Costa Rica rétorque que le Nicaragua n’a pas prouvé, sur la
base d’éléments factuels et objectifs, l’existence de dommages importants
et soutient que, même en l’absence de données de référencfe suffisantes, ce
dernier aurait pu apprécier l’impact de la construction de la routfe sur les

concentrations sédimentaires du fleuve en prenant ses propres mesurfes en
amont et en aval des travaux ; or il n’en a rien fait.

*

192. La Cour estime qu’il est inexact d’avancer, comme le fait le Nicarfa-

gua, que tout effet préjudiciable sur le Sanuan qui serait mesurable consti-
tuerait un dommage important. Le fleuve présente une charge sédimentaire

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5 Ord 1088.indb 134 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 730

view, the impact of the road’s contribution must be considered takingf
into account the elevated sediment load in the San Juan River which is

allegedly due to deforestation and poor land use practices by Costa Rica.
An expert for Nicaragua estimated the current sediment load to be
approximately 13,700,000 tonnes per year. In this context, Nicaragua
submits that there is a maximum load for sediment in the San Juan, and
that any additional amount of sediment delivered from the road to the

river is necessarily harmful.
189. Costa Rica responds that Nicaragua has not shown that the
San Juan River has a maximum sediment capacity that has been exceeded.
For Costa Rica, the question before the Court is whether the relative
impact of the road -derived sediment on the total load of the San Juan
River caused significant harm. Costa Rica claims that it did not. Accord -

ing to Costa Rica, the San Juan River naturally carries a heavy sediment
load, which is attributable to the geology of the region, and in particular
to the occurrence of earthquakes and volcanic eruptions in the drainage f
area of the river and its tributaries. The volume of sediment contributefd
by the road is insignificant in the context of the river’s total sedifment load

(estimated by Costa Rica at 12,678,000 tonnes per year), of which it rep -
resents a mere 0.6 per cent at most. The road -derived sediment is also
indiscernible considering the high variability in the river’s sedimenft loads
deriving from other sources. Costa Rica adds that, even if Nicaragua’s
figures were to be adopted, the sediment contribution due to the construfc -

tion of the road would still only represent a small proportion, within tfhe
order of 1 -2 per cent, of the total load transported by the San Juan. In
Costa Rica’s view, this amount is too small to have any significant impact.f
190. Nicaragua further argues, drawing on the commentary to the
International Law Commission’s Draft Articles on Prevention of Trans -
boundary Harm from Hazardous Activities, that any detrimental impact

of the construction of the road on the San Juan River need only be sus -
ceptible of being measured to qualify as significant harm. Since the
amount of sediment in the river due to the construction of the road is
measurable, as shown by the fact that both Nicaragua’s and Costa Rica’s
experts have estimated its amount, Nicaragua claims that it caused sig -

nificant harm.
191. Costa Rica retorts that Nicaragua has not shown significant harm
by factual and objective standards. It also argues that, even lacking anf
appropriate baseline, Nicaragua could have measured the impact of the
construction of the road on the river’s sediment concentrations by tafking

its own measurements upstream and downstream of the construction
works. However, Nicaragua failed to do so.

*

192. In the Court’s view, Nicaragua’s submission that any detrimental

impact on the river that is susceptible of being measured constitutes sig -
nificant harm is unfounded. Sediment is naturally present in the river ifn

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naturellement élevée et le Nicaragua n’a pas montré que les fniveaux de
sédiments présents sont tels que tout apport supplémentaire issfu de l’éro-

sion de la route entraînerait le franchissement de quelque «point critique»
s’agissant des effets préjudiciables. De plus, la Cour considère que, contra-i
rement aux allégations du Nicaragua, il ne s’agit pas en l’espèce de décider
si l’apport sédimentaire de la route dépasse un certain seuil dfe tolérance,
qui n’a pas été identifié en ce qui concerne le fleuve Sanf Juan. Elle n’est

donc pas convaincue par l’argument du Nicaragua voulant que la quantifté
totale de sédiments dans le fleuve provenant de la construction de fla route
cause par elle-même un dommage important.
193. La Cour examinera donc l’impact relatif des sédiments issus de la
route sur la charge sédimentaire globale actuelle du SanJuan. Sur ce point,
elle constate que la charge sédimentaire totale présente dans le fleuve n’a

pas été établie, le Nicaragua n’ayant pas produit de mesures directes des
concentrations en sédiments. En se fondant sur le rapport de son expefrt
principal, le Costa Rica a estimé la charge sédimentaire totale du San Juan
à quelque 12 678 000 tonnes par an, sur la base de mesures effectuées dans
le fleuve Colorado. Aucun chiffre comparable n’a été fourni pfar le Nicara -

gua, encore que son expert ait chiffré à environ 13 700 000 tonnes par an
la charge sédimentaire totale actuelle du fleuve San Juan.
194. La Cour relève que, d’après les éléments de preuve dont eflle dis -
pose et compte tenu des estimations fournies par les experts en ce qui
concerne la quantité de sédiments dans le fleuve provenant de laf construc-

tion de la route et la charge sédimentaire totale du fleuve San Juan, l’ap-
port sédimentaire attribuable à la route représente tout au plufs 2 % de la
charge totale du fleuve. La Cour considère qu’une telle proportifon ne per -
met pas de conclure à un dommage important, surtout s’il est tenu fcompte
de la forte variabilité naturelle des charges sédimentaires du flfeuve.
195. En tout état de cause, de l’avis de la Cour, les seules mesures qufi

ont été produites devant elle, soit celles qui figurent dans les rfapports de
l’INETER de 2011 et 2012, n’étayent pas l’affirmation du Nicaragua selon
laquelle les sédiments résultant de l’érosion de la route aufraient eu un
impact important sur les concentrations sédimentaires du fleuve. Laf com -
paraison des mesures prises en 2011, avant que la plus grande partie de la

route ne soit construite, avec celles de 2012, alors que les travaux étaient
engagés, montre que les concentrations présentes dans le San Juan sont
variables et que les affluents de ce dernier (notamment les rivièrefs SanCar -
los et Sarapiquí) contribuent de manière importante à sa séfdimentation.
Cependant, les données n’indiquent pas que la construction de la rfoute ait

eu un impact important sur les niveaux de sédimentation. Il en va de même
des mesures prises à El Castillo et en amont de Boca San Carlos, qui cor-
respondent au segment de route comportant les pentes les plus raides et
qui ne font, elles non plus, pas apparaître un effet important.
196. A la lumière de ce qui précède, la Cour conclut que le Nicaragufa
n’a pas établi que le seul fait que les concentrations sédimentfaires ont

augmenté dans le fleuve à la suite de la construction de la routfe a causé
des dommages transfrontières importants.

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5 Ord 1088.indb 136 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 731

large quantities, and Nicaragua has not shown that the river’s sedimefnt
levels are such that additional sediment eroded from the road passes a

sort of critical level in terms of its detrimental effects. Moreover, thfe
Court finds that, contrary to Nicaragua’s submissions, the present cafse
does not concern a situation where sediment contributed by the road
exceeds maximum allowable limits, which have not been determined for
the San Juan River. Thus, the Court is not convinced by Nicaragua’s

argument that the absolute quantity of sediment in the river due to the f
construction of the road caused significant harm per se.

193. The Court will therefore proceed to consider the relative impact
of the road-derived sediment on the current overall sediment load of the
San Juan River. In this regard, the Court notes that the total sediment

load of the San Juan River has not been established. Indeed, Nicaragua
has not provided direct measurements of sediment levels in the river.
Costa Rica, based on its main expert’s report, estimated the river’s total
sediment load to be approximately 12,678,000 tonnes per year using mea -
surements from the Colorado River. Nicaragua has not provided a com -

parable figure, although its expert stated that the current total sedimefnt
load of the San Juan River is roughly 13,700,000 tonnes per year.
194. On the basis of the evidence before it, and taking into account the
estimates provided by the experts of the amount of sediment in the riverf
due to the construction of the road and of the total sediment load of thfe

San Juan River, the Court observes that the road is contributing at
most 2 per cent of the river’s total load. It considers that significant harm
cannot be inferred therefrom, particularly taking into account the high f
natural variability in the river’s sediment loads.

195. In any event, in the Court’s view, the only measurements that are

before it, namely, those contained in the INETER reports from 2011 and
2012, do not support Nicaragua’s claim that sediment eroded from the f
road has had a significant impact on sediment concentrations in the rivefr.
A comparison of the measurements taken in 2011, when most of the road
had not yet been built, and in 2012, when construction works were under f

way, shows that sediment levels in the river are variable, and that tribfu -
taries (particularly the San Carlos and Sarapiquí Rivers) are major
sources of sediment for the San Juan. However, the data do not indicate
a significant impact on sediment levels from the construction of the roafd.
Moreover, the measurements taken at El Castillo and upstream of Boca

San Carlos, which are representative of the steepest stretch of the road,
show no significant impact.

196. In light of the above, the Court concludes that Nicaragua has not
established that the fact that sediment concentrations in the river incrfeased

as a result of the construction of the road in and of itself caused signfifi -
cant transboundary harm.

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5 Ord 1088.indb 137 19/10/16 12:01 732 certaines activitésf et construction d’unfe route (arrêt)

ii) L’atteinte qui aurait été portée à la morphologie du fl▯euve, à la
navigation et au programme de dragage du Nicaragua

197. La Cour recherchera à présent si l’apport sédimentaire attrifbuable
à la route, lequel représente, ainsi qu’elle l’a noté, tofut au plus 2 % de la

charge totale moyenne du fleuve, a causé, à un autre titre, des fdommages
importants. A cet égard, le moyen principal du Nicaragua concerne l’fim -
pact des sédiments provenant de la construction de la route sur la mofr -
phologie du San Juan, en particulier celle de son cours inférieur.
198. Les Parties conviennent pour l’essentiel que, si l’on part de l’fhypo-

thèse que, au point dénommé « Delta Colorado », 10 % des eaux du
San Juan se jettent dans son cours inférieur, ce dernier capterait envirofn
16% des sédiments en suspension et 20 % des sédiments grossiers présents
dans le bras principal. Elles s’entendent également sur le fait qufe, à la
différence du fleuve Colorado, qui est de taille beaucoup plus importante,

le San Juan inférieur n’a pas la capacité de transporter des charges sfup -
plémentaires, de sorte que les sédiments grossiers se déposent fsur son lit.
Les experts des Parties s’accordent par ailleurs pour dire que ces dépôts
ne se répartissent pas uniformément, mais ont tendance à s’accumuler
sous forme de hauts-fonds et de bancs de sable susceptibles d’entraver la

navigation, surtout pendant la saison sèche. Ils sont toutefois en défsac -
cord sur le point de savoir si et dans quelle mesure les sédiments plfus fins
en suspension se déposent eux aussi sur le lit du fleuve et, de manfière plus
générale, sur les effets de la construction de la route sur le défpôt des sédi-
ments dans le cours inférieur du San Juan.

199. Selon l’expert du Nicaragua, la totalité des sédiments grossierfs et
60% des sédiments fins provenant de la route qui pénètrent dans lfe
San Juan inférieur se déposent sur son lit. Le Nicaragua serait donc
contraint, pour préserver la navigabilité du cours inférieur, de draguer les
sédiments fins et grossiers qui s’y amassent. Il fait valoir que, fcelui -ci

étant déjà surchargé de sédiments, tout apport supplémfentaire en prove -
nance de la route lui cause des dommages importants en alourdissant sa
charge en matière de dragage. De surcroît, l’accumulation des sfédiments
issus de la route réduirait l’apport d’eau vers les zones humidfes situées en
aval, lequel est essentiel à leur équilibre écologique.

200. Le Nicaragua soutient en outre que les sédiments produits par
l’érosion de la route ont entraîné la formation, le long du fchenal du fleuve,
de deltas « énormes» qui nuisent à la navigabilité et, partant, lui causent
des dommages importants.
201. Le Costa Rica répond, en se fondant sur les conclusions de son

expert principal, que l’alluvionnement du SanJuan inférieur est un phéno -
mène naturel et inévitable qui est sans rapport avec la constructifon de la
route. Selon lui, les experts du Nicaragua ont par ailleurs considérafblement
exagéré la quantité de sédiments produits par la route qui sf’y déposent.
Premièrement, il soutient que seuls les sédiments grossiers s’afccumulent sur

le lit du chenal, les sédiments fins étant, pour l’essentiel, efmportés jusqu’à la
mer des Caraïbes. Deuxièmement, il n’existe selon lui aucun élément de

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(ii) Alleged harm to the river’s morphology, to navigation and to
Nicaragua’s dredging programme

197. The Court will now examine whether the sediment contributed by
the road, which the Court has noted corresponds to at most 2 per cent of

the river’s average total load, caused any other significant harm. Nifcara-
gua’s primary argument on the harm caused by the construction of the f
road concerns the impact of the resulting sediment on the morphology of f
the river, and particularly on the Lower San Juan.
198. The Parties broadly agree that, on the assumption that at “Delta

Colorado” 10 per cent of the waters of the San Juan River flow into the
Lower San Juan, approximately 16 per cent of the suspended sediments
and 20 per cent of the coarse load in the San Juan River would flow into
the Lower San Juan. They also concur that, unlike the much larger Colo -
rado River, the Lower San Juan has no unfilled capacity to transport

sediment. Thus, coarse sediment deposits on the bed of the Lower
San Juan. The Parties’ experts further agree that sediment that settles ofn
the riverbed does not spread evenly, but tends to accumulate in shoals
and sandbars that may obstruct navigation, especially in the dry season.f
They disagree, however, on whether and to what extent the finer sus -

pended sediments are also deposited on the riverbed and, more broadly,
on the effects of the construction of the road on sediment deposition inf
the Lower San Juan.

199. According to Nicaragua’s expert, all of the coarse sediment and
60 per cent of the fine sediment contributed by the road to the Lower
San Juan settle on the riverbed. To maintain the navigability of the river,
Nicaragua is thus required to dredge the fine and coarse sediment that
accumulates in the Lower San Juan. In Nicaragua’s view, in a river that is

already overloaded with sediment such as the Lower San Juan, any addi -
tion of sediment coming from the road causes significant harm to Nicara-
gua because it increases its dredging burden. Furthermore, the accumulatfion
of road -derived sediment reduces the flow of fresh water to the wetlands
downstream, which depend on it for their ecological balance.

200. Nicaragua also argues that sediment eroded from the road cre -
ated “huge” deltas along the river’s channel that obstruct navifgation,
thereby causing significant harm to Nicaragua.

201. Costa Rica responds, relying on the evidence of its main expert,

that the aggradation of the Lower San Juan is an inevitable natural phe -
nomenon that is unrelated to the construction of the road. For Costa Rica,
Nicaragua’s experts also dramatically overestimate the amount of
road-derived sediment that is deposited in the Lower San Juan. First, in
Costa Rica’s view, only coarse sediment accumulates on the riverbed,

whereas most of the fine sediment is washed into the Caribbean Sea.
Secondly, Costa Rica argues that there is no evidence that coarse sediment

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preuve établissant que des sédiments grossiers produits par la roufte aient
effectivement atteint le cours inférieur du San Juan. Le dépôt sédimentaire

n’est pas un processus linéaire ; en particulier, les sédiments ont tendance à
s’accumuler dans des parties du fleuve qu’on appelle « secteurs de réponse»,
et peuvent y demeurer pendant des années avant d’être charriéfs vers l’aval.
De plus, souligne-t-il, les estimations des Parties sont fondées sur un certain
nombre d’hypothèses non vérifiées, parmi lesquelles la réfpartition estima -

tive des eaux et des charges sédimentaires entre le fleuve Colorado et le
San Juan inférieur au point dénommé « Delta Colorado ». Le Costa Rica
affirme par ailleurs que la thèse du Nicaragua en matière de dommfages
repose sur l’hypothèse erronée selon laquelle les sédiments fs’accumulant sur
le lit du San Juan inférieur devront nécessairement être dragués.
202. S’agissant des deltas situés le long de sa propre rive, le Costa Rica

soutient que le Nicaragua n’a pas établi que leur formation étafit due à la
construction de la route. Ainsi, des images satellite démontreraient fqu’au
moins deux de ces deltas sont antérieurs au projet routier. Le Costa Rica
souligne au demeurant qu’il existe des deltas comparables sur la rivef nica -
raguayenne du fleuve. En tout état de cause, leur incidence sur la fmor -

phologie du fleuve et sur la navigation serait négligeable, compte ftenu de
leur taille limitée par rapport à la largeur du fleuve.

*

203. La Cour relève que le Nicaragua n’a produit aucune preuve directe
des changements morphologiques que le SanJuan inférieur aurait subis ou
de la dégradation de sa navigabilité depuis le commencement de la fconstruc -
tion de la route. L’argumentation du Nicaragua repose là encore sufr la
modélisation et les estimations réalisées par ses experts, lesqfuelles n’ont pas
été étayées par des données concrètes. A cet égard,f la Cour souligne la

grande incertitude qui entoure le volume des sédiments provenant de lf’ér-o
sion de la route qui seraient parvenus jusqu’au San Juan inférieur et se
seraient déposés sur son lit. Ainsi, le Nicaragua n’a pas fourni de preuve
scientifique pour établir la répartition des eaux et des charges sfédimentaires
au point dénommé « Delta Colorado », se contentant de fonder ses estima-

tions sur un rapport de la régie costa -ricienne d’électricité, lui-même fondé
sur des mesures prises exclusivement dans le fleuveColorado.
204. La Cour estime par ailleurs établi, au vu des rapports et exposés f
d’expert qui lui ont été soumis, que l’accumulation des sédiments est un
phénomène naturel et ancien dans le San Juan inférieur et que ceux -ci se

déposent le long du fleuve selon un processus non linéaire. Les fsédiments
produits par la route sont un facteur parmi d’autres pouvant avoir unf
impact sur l’alluvionnement du San Juan inférieur. La Cour considère en
conséquence que les éléments produits par le Nicaragua ne prouvfent pas
que les changements morphologiques qu’aurait subis ce cours d’eau f
puissent être spécifiquement attribués à la construction de fla route.

205. S’agissant de l’allégation du Nicaragua selon laquelle la constfruc -
tion de la route a causé un accroissement considérable de la quantfité de

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5 Ord 1088.indb 140 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 733

from the road has actually reached the Lower San Juan. Sediment deposi-
tion is not a linear process ; in particular, sediment tends to accumulate in

stretches of the river called “response reaches” and may stay therfe for
years before it is transported further down the channel. Moreover,
Costa Rica points out that the Parties’ estimates are based on a number
of untested assumptions, including estimates of the split of flow and sedi -
ment loads between the Colorado River and the Lower San Juan at

“Delta Colorado”. Costa Rica further argues that Nicaragua’s case on
harm rests on the mistaken assumption that sediment accumulating on
the bed of the Lower San Juan will necessarily need to be dredged.

202. As to the deltas along the Costa Rican bank of the river,

Costa Rica argues that Nicaragua has not shown that they were created
as a result of the construction of the road. For example, satellite imagery
demonstrates that at least two of these deltas pre-date the road. CostaRica
further points out that similar deltas exist on the Nicaraguan bank of tfhe
river. In any event, their impact on the morphology of the river and on f

navigation is insignificant because of their small size relative to the width
of the river.

*

203. The Court notes that Nicaragua has produced no direct evidence
of changes in the morphology of the Lower San Juan or of a deteriora -
tion of its navigability since the construction of the road began. Nicarfa -
gua’s case once again rests on modelling and estimates by its expertsf,
which have not been substantiated by empirical data. The Court observes f
in this regard that there are considerable uncertainties concerning the fvo-l

ume of sediment eroded from the road that has allegedly reached the
Lower San Juan and deposited on its bed. For example, Nicaragua has
not adduced scientific evidence on the division of flow and sediment lfoads
at “Delta Colorado”, but based its estimates on a report of the Costa Rican
Institute of Electricity, which is in turn based on measurements taken

only in the Colorado River.

204. The Court further considers that the expert evidence before it
establishes that the accumulation of sediment is a long -standing natural
feature of the Lower San Juan, and that sediment delivery along the San

Juan is not a linear process. The road -derived sediment is one of a num -
ber of factors that may have an impact on the aggradation of the Lower
San Juan. The Court therefore considers that the evidence adduced by
Nicaragua does not prove that any morphological changes in the Lower
San Juan have been caused by the construction of the road in particular.

205. As to Nicaragua’s claim that the construction of the road has had
a significant adverse impact on its dredging burden, the Court notes thaft

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5 Ord 1088.indb 141 19/10/16 12:01 734 certaines activitésf et construction d’unfe route (arrêt)

sédiments qu’il lui faut draguer, la Cour relève qu’il n’fa fourni aucune
preuve de ce que ses opérations de dragage se seraient intensifiéefs en rai -

son de la construction de la route. Elle fait également observer sur ce
point que le Nicaragua a amorcé son programme de dragage avant le
début des travaux routiers (voir les paragraphes 63-64 ci-dessus) et rap -
pelle, en tout état de cause, qu’elle a déjà constaté quef la hausse des
concentrations sédimentaires du fleuve due à cette construction fétait tout
au plus de 2 % (voir le paragraphe 194 ci-dessus). La Cour observe que

rien n’indique que les sédiments résultant de la construction dfe la route
soient davantage susceptibles de se déposer au fond du fleuve que ceux
provenant d’autres sources. Ainsi, les sédiments issus de la routef repré -
senteraient au maximum 2 % des volumes dragués par le Nicaragua dans
le cours inférieur du San Juan. Elle n’est donc pas convaincue que les

sédiments issus de la route aient contribué de manière importanfte à l’ex -
haussement du lit du San Juan inférieur ou à l’alourdissement de la tâche
du Nicaragua en matière de dragage.
206. Enfin, la Cour en vient à l’argument du Nicaragua selon lequel la
formation de deltas sédimentaires le long de la rive costa -ricienne du
fleuve a causé un préjudice important à la morphologie de celui-ci et à sa

navigabilité. De l’avis de la Cour, les éléments de preuve pfhotographiques
produits par le Nicaragua indiquent l’existence, sur la rive costa -ricienne
du fleuve, de deltas où s’accumulent des sédiments provenant fde la
construction de la route. Le Nicaragua a affirmé que, là où sef trouvait la
partie de la route la plus escarpée, il y avait huit «énormes» deltas, sans
toutefois être en mesure de préciser le nombre total des deltas réfsultant

prétendument de la construction de la route. La Cour relève en outfre que
les images satellite versées au dossier montrent qu’au moins deux fde ces
deltas sont antérieurs à la construction de la route. En tout éftat de cause,
elle considère que le Nicaragua n’a pas présenté suffisammefnt d’éléments
pour établir que ces deltas, qui n’occupent que la bordure du chenfal sur

la rive costa -ricienne, aient eu un impact préjudiciable important sur la
morphologie du fleuve ou sur la navigation.
207. Pour les raisons qui précèdent, la Cour conclut que le Nicaragua
n’a pas démontré que l’apport sédimentaire attribuable àf la route a porté
une atteinte grave à la morphologie et à la navigabilité du flfeuve San Juan
et de son cours inférieur, ou a alourdi de manière importante la tfâche du

Nicaragua en matière de dragage.

iii) L’atteinte qui aurait été portée à la qualité de l’▯eau et à l’écosys
tème aquatique

208. La Cour examinera à présent la prétention du Nicaragua concer -
nant l’atteinte qui aurait été portée à la qualité de fl’eau et à l’écosystème
aquatique. Dans ses écritures, le Nicaragua a affirmé que l’acfcroissement
des concentrations sédimentaires dans le fleuve, par suite de la construc -
tion de la route, avait nui de manière importante à certaines espèfces de

poissons, dont bon nombre appartiennent à des familles vulnérables aux
charges sédimentaires élevées, ainsi qu’aux macro-invertébrés et aux colo-

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5 Ord 1088.indb 142 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 734

Nicaragua has adduced no evidence of an increase in its dredging activi -
ties due to the construction of the road. In this connection, the Court falso

recalls that Nicaragua initiated its dredging programme before the con -
struction of the road started (see paragraphs 63-64 above). In any event,
the Court recalls its conclusion that the construction of the road has
caused an increase in sediment concentrations in the river correspondingf
to at most 2 per cent (see paragraph 194 above). The Court observes that
there is no evidence that sediment due to the construction of the road ifs

more likely to settle on the riverbed than sediment from other sources. f
Thus, sediment coming from the road would correspond to at
most 2 per cent of the sediment dredged by Nicaragua in the Lower
San Juan. The Court is therefore not convinced that the road -derived
sediment led to a significant increase in the bed level of the Lower

San Juan or in Nicaragua’s dredging burden.

206. Finally, the Court turns to Nicaragua’s claim that the sediment
deltas along the Costa Rican bank of the river have caused significant
harm to the river’s morphology and to navigation. In the Court’s vfiew,

the photographic evidence adduced by Nicaragua indicates that there are f
deltas on the Costa Rican bank of the river to which the construction of
the road is contributing sediment. The Court observes that Nicaragua
submitted that in the steepest stretch of the road there are eight “hfuge”
deltas but was not able to specify the total number of deltas allegedly fcre-
ated as a consequence of the construction of the road. The Court further

notes that satellite images in the record show that at least two of thesfe
deltas pre-date the road. In any event, the Court considers that Nicara -
gua has not presented sufficient evidence to prove that these deltas, wfhich
only occupy the edge of the river’s channel on the Costa Rican bank,
have had a significant adverse impact on the channel’s morphology or fon

navigation.

207. For the foregoing reasons, the Court concludes that Nicaragua
has not shown that sediment contributed by the road has caused signifi -
cant harm to the morphology and navigability of the San Juan River and
the Lower San Juan, nor that such sediment significantly increased Nica -

ragua’s dredging burden.

(iii)Alleged harm to water quality and the aquatic ecosystem

208. The Court will now consider Nicaragua’s contention concerning
harm to water quality and the aquatic ecosystem. In its written pleadingfs,
Nicaragua alleged that the increased sediment concentrations in the rivefr
as a result of the construction of the road caused significant harm to fifsh
species, many of which belong to families that are vulnerable to elevatefd

levels of sediments, to macro -invertebrates and to algal communities in
the river. Furthermore, according to Nicaragua, the road’s sediment

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5 Ord 1088.indb 143 19/10/16 12:01 735 certaines activitésf et construction d’unfe route (arrêt)

nies algales. De plus, selon le Nicaragua, les sédiments provenant def la
route ont entraîné la dégradation de la qualité de l’eau fdu fleuve. Pour

démontrer le dommage causé aux organismes aquatiques et à la qufalité de
l’eau, il s’est fondé, entre autres, sur un rapport d’expertf constatant, à
partir d’échantillons prélevés sur 16 deltas du fleuve, que tant la richesse
que l’abondance des espèces de macro -invertébrés étaient sensiblement
inférieures sur la rive méridionale que sur la rive septentrionalef.

209. Au cours de la procédure orale, l’argumentation du Nicaragua,
initialement axée sur l’existence d’un dommage effectif à l’fécosystème du
fleuve, a été réorientée pour porter plutôt sur celle df’un risque de dom -
mage. Les Parties conviennent désormais qu’aucune étude n’a fété menée
au sujet des espèces de poissons habitant le fleuve San Juan afin de déter-
miner si celles -ci étaient vulnérables aux charges sédimentaires élevées.f

Cependant, le Nicaragua affirme que le « diagnostic de l’impact sur l’envi-
ronnement » réalisé par le Costa Rica et l’étude de suivi effectuée au mois
de janvier 2015 par le centre costa -ricien des sciences tropicales (ci -après
le «CCT», suivant le sigle en espagnol) ont démontré que la route porftait
préjudice aux macro -invertébrés et à la qualité des eaux dans les affluents

du fleuve San Juan. Le CCT a mesuré la qualité de l’eau dans les affluents
costa -riciens en amont et en aval de la route, enregistrant une qualité inffé-
rieure en aval, ce qui, selon le Nicaragua, démontre le risque qu’un dom -
mage soit causé au fleuve lui -même par l’effet cumulé des impacts de ces
affluents.

210. Selon le Costa Rica, les moyens du Nicaragua se rapportant à
l’impact sur les espèces de poissons ne peuvent être retenus fafute de
preuve d’un dommage effectif. S’appuyant sur l’avis émis par l’un de ses
experts, il soutient que les espèces habitant le fleuve sont selon ftoute vrai-
semblance bien adaptées aux charges sédimentaires élevées etf fluctuantes,
et ont une tolérance élevée à l’égard de telles conditfions. S’agissant des

macro-invertébrés et de la qualité de l’eau, il avance que l’éftude du CCT
ne révèle aucun impact important et que, en tout état de cause,f les résul -
tats qu’elle contient reposent sur des échantillons prélevés sur de petits
affluents costa -riciens et ne sauraient être appliqués au cours d’eau beau -
coup plus important qu’est le fleuve San Juan. Il fait en outre valoir que

le rapport d’expert produit par le Nicaragua n’étaye pas suffisamment la f
prétention de ce dernier selon laquelle la construction de la route afurait
eu un impact préjudiciable sur les macro -invertébrés habitant les deltas
situés le long de la rive sud du fleuve.

*

211. La Cour observe que le Nicaragua n’a pas prouvé qu’il aurait
effectivement été porté atteinte aux poissons vivant dans le flfeuve San Juan
et n’a pas su davantage identifier avec précision les espèces afuxquelles la
construction de la route aurait porté préjudice.

212. De l’avis de la Cour, le « diagnostic de l’impact sur l’environne -
ment» sur lequel s’appuie le Nicaragua montre tout au plus que la consftr-uc

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5 Ord 1088.indb 144 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 735

caused a deterioration in the water quality of the river. To prove harm fto
aquatic organisms and water quality, Nicaragua relied inter alia on an

expert report based on sampling at 16 deltas in the river, which concluded
that both species richness and abundance of macro -invertebrates were
significantly lower on the south bank than on the north bank.

209. During the course of the oral proceedings, Nicaragua’s case
shifted from its prior claim of actual harm to the river’s ecosystem fto a
claim based on the risk of harm. The Parties now agree that there have
been no studies of the fish species in the San Juan River to determine
whether they are vulnerable to elevated levels of sediment. However,
Nicaragua claims that Costa Rica’s Environmental Diagnostic Assess -

ment and the follow-up study carried out in January 2015 by the Tropical
Science Centre (hereinafter “CCT”, by its Spanish acronym) show fthat
the road is harming macro-invertebrates and water quality in the tributar-
ies that flow into the San Juan River. The CCT measured water quality in
Costa Rican tributaries upstream and downstream of the road and

recorded a lower water quality downstream of the road. For Nicaragua,
this demonstrates a risk of harm to the river itself due to the cumulatifve
impact of those tributaries.

210. For Costa Rica, Nicaragua’s case on the impact on fish species
fails due to the lack of evidence of actual harm. Relying on one of its f
experts, Costa Rica argues that it is very likely that species living in the
river are adapted to conditions of high and variable sediment loads and f
are highly tolerant of such conditions. As to macro -invertebrates and
water quality, Costa Rica submits that the CCT study shows no signifi -

cant impact. In any event, its results are based on sampling on small trfib-
utary streams in Costa Rica, and cannot be transposed to the much larger
San Juan River. Costa Rica further argues that the expert report adduced
by Nicaragua does not provide sufficient support for Nicaragua’s clafim
that the construction of the road has had an adverse impact on

macro -invertebrates living in deltas along the south bank of the river.

*

211. The Court observes that Nicaragua has not presented any evi -
dence of actual harm to fish in the San Juan River, nor has it identified
with precision which species of fish have allegedly been harmed by the
construction of the road.

212. In the Court’s view, the Environmental Diagnostic Assessment
relied upon by Nicaragua only shows that the construction of the road

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5 Ord 1088.indb 145 19/10/16 12:01 736 certaines activitésf et construction d’unfe route (arrêt)

tion de la route a eu des effets localisés sur les populations de macfro -
invertébrés et sur la qualité de l’eau de certains petits affluents costa -

riciens du San Juan. Elle n’est toutefois pas convaincue que les résultats
du «diagnostic de l’impact sur l’environnement » et de l’étude de suivi
puissent être appliqués au fleuve, dont la largeur moyenne est dfe près
de 300 mètres. Pour ce qui est du rapport d’expert présenté par le fNicara-
gua, elle estime qu’il est difficile de déterminer la mesure dansf laquelle les

différences relevées entre les rives nord et sud du fleuve quantf à la richesse
et à l’abondance des populations de macro -invertébrés peuvent être attri-
buées exclusivement à la construction de la route, plutôt qu’fà d’autres fa-c
teurs tels que la superficie du bassin versant et les niveaux de nutrimefnts qui
s’y trouvent.
213. A la lumière de ce qui précède, la Cour conclut que le Nicaragufa

n’a pas prouvé que la construction de la route a porté une attefinte impor-
tante à l’écosystème du fleuve et à la qualité de sefs eaux.

iv) Les autres dommages allégués

214. Le Nicaragua allègue en outre que la construction de la route a eu
un impact préjudiciable sur la santé des communautés riverainesf, laquelle
est tributaire de la salubrité du fleuve lui -même. Il ajoute que la route a
par ailleurs sérieusement compromis le potentiel touristique de la réfgion,

en raison de l’impact visuel qu’elle a eu sur le paysage naturel. fEnfin, il
argue que, outre les dommages transfrontières qu’elle a déjàf causés, la
route pose un risque important à cet égard pour l’avenir. Selonf lui, la
possibilité d’un déversement de matières toxiques en cas de ftransport sur
la route de substances dangereuses ainsi que toute forme d’aménagefment
ultérieur de la rive droite du fleuve, du fait du développement fdes activités

agricoles et commerciales, sont des sources supplémentaires de risquef.

215. Le Costa Rica répond que le Nicaragua n’a produit aucun élé -
ment de preuve montrant qu’un dommage ait effectivement été caufsé à
l’industrie du tourisme ou à la santé des communautés riverafines, pas

plus qu’il n’a expliqué le fondement juridique de ses prétenftions. En
outre, il fait valoir que l’argument du Nicaragua concernant le risqufe de
déversement de substances toxiques n’est que pure conjecture :la régle-
mentation costa -ricienne de 1995 sur le transport des matières dange -
reuses dispose que celles -ci ne peuvent être transportées que sur les routes

agréées à cet effet et la route 1856 n’en fait pas partie.

*

216. La Cour conclut que le Nicaragua n’a pas étayé ses prétentiofns
concernant le préjudice qui aurait été causé au tourisme et fà la santé. Elle
estime par ailleurs que ses moyens liés au risque de déversement de subs -
tances toxiques dans le fleuve et à l’aménagement de la rive costa -ricienne

du fleuve sont de nature conjecturale et n’établissent l’exisftence d’aucun
dommage. Ces moyens ne peuvent donc être retenus.

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5 Ord 1088.indb 146 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 736

has had a localized impact on macro-invertebrate communities and water
quality in small Costa Rican streams draining into the San Juan River.

However, the Court is not persuaded that the results of the Environmen -
tal Diagnostic Assessment and the follow -up study can be transposed to
the San Juan River, which has an average width of nearly 300 metres. As
regards the expert report submitted by Nicaragua, the Court finds it diff -
ficult to attribute any differences in macro -invertebrate richness and

abundance between the north and the south banks of the river to the
construction of the road alone, as opposed to other factors such as the f
size of the catchment area and the nutrient levels therein.

213. On the basis of the foregoing considerations, the Court finds that

Nicaragua has not proved that the construction of the road caused sig -
nificant harm to the river’s ecosystem and water quality.

(iv) Other alleged harm

214. Nicaragua also alleges that the construction of the road has had
an adverse impact on the health of the communities along the river, whicfh
is dependent upon the health of the river itself. Furthermore, in Nicaraf -
gua’s view, the road significantly affected the area’s tourism potfential as

it has a negative visual impact on the natural landscape. Finally, Nicarfa-
gua argues that, in addition to the transboundary harm that the road has
already caused, it poses a significant risk of future transboundary harmf.
According to Nicaragua, additional risks derive from the possibility
of spills of toxic materials into the river whenever hazardous substances
are transported on the road, and from any further development of the

right bank of the river, such as increased agricultural and commercial
activities.
215. Costa Rica responds that Nicaragua did not adduce any evidence
of actual impact on tourism or on the health of riparian communities.
Moreover, it did not explain the legal basis of its claims. Furthermore,f

Costa Rica contends that Nicaragua’s arguments on the risk of toxic
spills in the river are based entirely on speculation : Costa Rica’s 1995
Regulations for the Ground Transportation of Hazardous Material pro -
vide that hazardous substances can only be transported on authorized
roads, and Route 1856 is not one of them.

*

216. The Court finds that Nicaragua did not substantiate its conten -
tions regarding harm to tourism and health. The Court further observes
that Nicaragua’s arguments concerning the risk of toxic spills into tfhe
river and of further development of the Costa Rican bank of the river are

speculative and fail to show any harm. Therefore, these arguments fail.

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5 Ord 1088.indb 147 19/10/16 12:01 737 certaines activitésf et construction d’unfe route (arrêt)

c) Conclusion

217. A la lumière de ce qui précède, la Cour conclut que le Nicaragufa

n’a pas prouvé que la construction de la route lui ait causé defs dommages
transfrontières importants. La prétention du Nicaragua selon laqueflle le
Costa Rica aurait manqué à ses obligations de fond en droit internfational
coutumier relatives aux dommages transfrontières doit être rejetéfe.

2. Allégations de violation d’obligations d’origine conventionnell▯e

218. Le Nicaragua soutient par ailleurs que le Costa Rica a contrevenu
à des obligations de fond énoncées par divers textes universelsf et régio -
naux. Premièrement, il fait valoir que le CostaRica a violé le paragraphe1
de l’article 3 de la convention de Ramsar. Deuxièmement, il avance que le

Costa Rica a agi au mépris des but et objet de l’accord de 1990 sur les
zones frontalières protégées entre le Costa Rica et le Nicaragua (l’«accord
sur le SIAPAZ »)). Troisièmement, il allègue que, par ses activités, le f
Costa Rica a violé les articles 3 et 8 de la convention sur la diversité bio
logique. Quatrièmement, il affirme que le Costa Rica a manqué à diverses

dispositions de la convention concernant la conservation de la biodiver -
sité et la protection des zones prioritaires de faune et de flore sfauvages
d’Amérique centrale. Cinquièmement, il dénonce la violation fde la
convention centraméricaine pour la protection de l’environnement et du
protocole de Tegucigalpa portant modification de la Charte de l’Organfi -

sation des Etats d’Amérique centrale. Enfin, il soutient que le Cofsta Rica
a enfreint l’article 3 de l’accord régional concernant les mouvements
transfrontières de déchets dangereux en omettant d’adopter et dfe mettre
en œuvre l’approche de précaution prévue par ce texte en ce fqui concerne
les problèmes de pollution.

219. En réponse à ces allégations, le Costa Rica soutient tout d’abord
que, le Nicaragua n’ayant pas réussi à démontrer que la consftruction de
la route a causé un dommage transfrontière important, ses prétefntions
doivent être rejetées. Il souligne par ailleurs que la constructiofn de la
route est sans effet sur les zones humides protégées du Nicaragua frelevant

de la convention de Ramsar et déclare de surcroît que le Nicaragua n’a
désigné aucune des dispositions de l’accord sur le SIAPAZ qui afuraient
été enfreintes. Le Costa Rica avance en outre que la convention centra -
méricaine pour la protection de l’environnement et le protocole def Tegu-
cigalpa sont complètement étrangers au présent différend et que, s’agissant

de l’accord régional concernant les mouvements transfrontières de déchets
dangereux, les prétentions du Nicaragua n’ont aucun fondement factfuel.

*

220. La Cour observe que le Nicaragua et le Costa Rica sont tous deux

parties aux textes invoqués par le premier. Indépendamment de la qfues -
tion du caractère contraignant ou non de certaines des dispositions en

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(c) Conclusion

217. In light of the above,the Court concludes that Nicaragua has not

proved that the construction of the road caused it significant transbound -
ary harm. Therefore, Nicaragua’s claim that Costa Rica breached its sub-
stantive obligations under customary international law concerning
transboundary harm must be dismissed.

2. Alleged breaches of treaty obligations

218. Nicaragua further argues that Costa Rica violated substantive
obligations contained in several universal and regional instruments. Firfst,
it contends that Costa Rica breached Article 3, paragraph 1, of the
Ramsar Convention. Secondly, it argues that Costa Rica acted contrary

to the object and purpose of the 1990 Agreement over the Border Pro -
tected Areas between Nicaragua and Costa Rica (“SI -A-PAZ Agree -
ment”). Thirdly, Nicaragua alleges that, by its activities, Costa Rica
violated Articles 3 and 8 of the Convention on Biological Diversity.
Fourthly, it claims that Costa Rica violated several provisions of the

Convention for the Conservation of the Biodiversity and Protection of
Priority Wilderness Areas in Central America. Fifthly, it alleges viola -
tions of the Central American Convention for the Protection of the Envirf -
onment and the Tegucigalpa Protocol to the Charter of the Organization
of Central American States. Finally, Nicaragua contends that Costa Rica

breached Article 3 of the Regional Agreement on the Transboundary
Movement of Hazardous Wastes, on the ground that it did not adopt and
implement the precautionary approach to pollution problems provided
for in that instrument.

219. In response to these allegations, Costa Rica argues at the outset
that, since Nicaragua failed to prove that the construction of the road f
caused any significant transboundary harm, its contentions must fail.
Costa Rica further points out that the construction of the road does not
touch upon protected Nicaraguan wetlands falling within the Ramsar

Convention. Moreover, it states that Nicaragua has identified no provi -
sion of the SI-A-PAZ Agreement that was allegedly breached. Costa Rica
further maintains that the Central American Convention for the Protec -
tion of the Environment and the Tegucigalpa Protocol are of no relevancef
to the present dispute and that there is no factual basis for Nicaragua’fs

contentions regarding the Regional Agreement on the Transboundary
Movement of Hazardous Wastes.

*

220. The Court notes that both Nicaragua and Costa Rica are parties

to the instruments invoked by Nicaragua. Irrespective of the question of
the binding character of some of the provisions at issue, the Court

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cause, la Cour fait remarquer que le Nicaragua se contente d’allégfuer la
violation par le Costa Rica des instruments concernés, sans expliquer en

quoi celui -ci aurait transgressé leurs «objectifs» ou les dispositions citées,
surtout en l’absence de preuve de dommage important à l’environfnement
(voir le paragraphe 217 ci-dessus). La Cour estime en conséquence que le
Nicaragua n’a pas réussi à montrer que le Costa Rica aurait méconnu les
textes précités.

3. L’obligation de respecter l’intégrité territoriale du Nicaragua et sa
souveraineté sur le fleuve San Juan

221. Le Nicaragua allègue encore que les deltas formés par les sédi -
ments provenant de l’érosion de la route constituent autant « d’avancées

matérielles, d’incursions du Costa Rica sur le territoire relevant de [sa]
souveraineté … par l’action des sédiments » et que leur présence constitue
un « empiètement» sur le territoire nicaraguayen. En outre, il soutient que
le rejet dans le fleuve, par le Costa Rica, de sédiments, de terre, de végé -
tation arrachée et d’arbres abattus constitue une menace grave àf l’exer -
cice de son droit de navigation sur le San Juan, droit qui découle

directement de sa souveraineté sur ce dernier. C’est pourquoi il afffirme
que, par ses agissements et ses activités, le Costa Rica a porté atteinte à
son intégrité territoriale et à sa souveraineté sur le flefuve San Juan, qu’il
tient du traité de 1858.
222. Le Costa Rica argue pour sa part que la réalisation de travaux

d’infrastructure routière dans les strictes limites de son territofire n’em -
porte aucune violation de la frontière délimitée par le traitéf de 1858 ou de
la souveraineté du Nicaragua, ni aucune atteinte au droit de ce dernifer de
naviguer sur le fleuve San Juan. Il soutient par ailleurs que le traité de
1858 n’a aucune incidence sur l’espèce, puisqu’il ne s’apfplique pas aux

questions en litige.
223. La Cour estime que, indépendamment de la question de savoir si la
formation de deltas sédimentaires peut être regardée comme une fconsé -
quence de la construction de la route, la thèse avancée par le Nicfaragua
pour établir la violation de son intégrité territoriale par l’faction des sédi -
ments n’est pas convaincante. Il n’y a aucune preuve que le Costa fRica ait

exercé une quelconque autorité sur le territoire nicaraguayen ou yf ait mené
une quelconque activité. Par ailleurs, comme il a déjà étéf exposé aux para -
graphes 203 à 207 ci -dessus, le Nicaragua n’a pas démontré que la
construction de la route a fait obstacle à son droit de navigation sufr le
fleuve San Juan. En conséquence, la demande du Nicaragua concernant la

violation de son intégrité territoriale et de sa souveraineté dfoit être rejetée.

C. Réparations

224. Le Nicaragua invite la Cour à dire et juger que, par ses agissements,f
le Costa Rica a manqué à l’obligation de ne pas porter atteinte à l’intégrité

du territoire nicaraguayen, à l’obligation de ne pas causer de domfmage à

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5 Ord 1088.indb 150 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 738

observes that, in relation to these instruments, Nicaragua simply makes f
assertions about Costa Rica’s alleged violations and does not explain how

the “objectives” of the instruments or provisions invoked would have
been breached, especially in the absence of proof of significant harm tof
the environment (see paragraph 217 above). The Court therefore consid -
ers that Nicaragua failed to show that Costa Rica infringed the
above-mentioned instruments.

3. The obligation to respect Nicaragua’s territorial integrity and sovereignty
over the San Juan River

221. Nicaragua further alleges that the deltas created by sediment
eroded from the road are “physical invasions, incursions by Costa Rica

into Nicaragua’s sovereign territory . . . through the agency of sediment”
and that their presence constitutes “trespass” into Nicaragua’sf territory.
Moreover, Nicaragua maintains that the dumping of sediments, soil,
uprooted vegetation and felled trees into the river by Costa Rica poses a
serious threat to the exercise of Nicaragua’s right of navigation on fthe
San Juan, which is based on its sovereignty over the river. Nicaragua

therefore claims that, by its conduct and activities, Costa Rica violated
Nicaragua’s territorial integrity and sovereignty over the San Juan River,
as established by the 1858 Treaty.

222. Costa Rica argues that undertaking road infrastructure works

entirely within its territory does not infringe the boundary delimited bfy
the 1858 Treaty or violate Nicaragua’s sovereignty, nor does it affect
Nicaragua’s right to navigate the San Juan River. Furthermore,
Costa Rica maintains that the 1858 Treaty has no bearing on this case, as
it does not regulate the issues that are at stake here.

223. The Court considers that, whether or not sediment deltas are cre -
ated as a consequence of the construction of the road, Nicaragua’s theory
to support its claim of a violation of its territorial integrity via sediment
is unconvincing. There is no evidence that Costa Rica exercised any
authority on Nicaragua’s territory or carried out any activity thereifn.

Moreover, for the reasons already expressed in paragraphs 203 to 207
above, Nicaragua has not shown that the construction of the road
impaired its right of navigation on the San Juan River. Therefore, Nica -
ragua’s claim concerning the violation of its territorial integrity afnd sov -
ereignty must be dismissed.

C. Reparation

224. Nicaragua requests the Court to adjudge and declare that, by its
conduct, Costa Rica has breached its obligation not to violate Nicara -

gua’s territorial integrity its obligation not to damage Nicaraguan terri -

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5 Ord 1088.indb 151 19/10/16 12:01 739 certaines activitésf et construction d’unfe route (arrêt)

celui-ci, ainsi qu’aux obligations lui incombant au titre du droit internatfi-o
nal général et des traités applicables en matière de protectfion de l’environ -

nement (conclusions finales, point1; voir le paragraphe 52 ci-dessus).
A la lumière des motifs exposés ci-dessus, la Cour estime que la consta-
tation par elle de ce que le Costa Rica a violé son obligation d’efffectuer
une évaluation de l’impact sur l’environnement est pour le Nicafragua une
mesure de satisfaction appropriée.

225. Deuxièmement, le Nicaragua demande à la Cour d’ordonner au
Costa Rica « de mettre fin à tous les faits internationalement illicites en
cours qui portent atteinte ou sont susceptibles de porter atteinte [à ses]
droits » (ibid., point 2 i)).
La Cour considère que le fait que le Costa Rica n’ait pas procédé à une
évaluation de l’impact sur l’environnement ne porte pas aujourd’hui

atteinte aux droits du Nicaragua, et n’est pas susceptible d’avoirf cet effet
à l’avenir. Il n’existe en conséquence aucune raison d’acfcorder la répara -
tion demandée.
226. Troisièmement, le Nicaragua invite la Cour à ordonner au
Costa Rica de rétablir, dans la mesure du possible, la situation qui existafit

avant la construction de la route et de l’indemniser des dommages auxf -
quels il n’est pas remédié par voie de restitution (ibid., points 2 ii) et iii)).
La Cour rappelle que la restitution et l’indemnisation sont des formefs de
réparation du préjudice matériel. Or elle constate que, bien que le
Costa Rica ait manqué à l’obligation de mener une évaluation de l’impact

sur l’environnement, il n’a pas été établi que la construfction de la route ait
causé des dommages importants au Nicaragua ou emporté manquement àf
d’autres obligations de fond en droit international, et le rétablifssement de
la région où est située la route dans son état original ne constituerait pas
une réparation appropriée au manquement, par le Costa Rica, à son obli -
gation d’effectuer une évaluation de l’impact sur l’environnfement (voir

Usines de pâte à papier sur le fleuve Uruguay (Argentine c. Uruguay), arrêt,
C.I.J. Recueil 2010 (I), p. 103, par. 271). Pour les mêmes raisons, la Cour
ne fera pas droit à la demande d’indemnisation du Nicaragua.
Le Nicaragua n’ayant pas réussi à prouver que des dommages impofr -
tants avaient été causés, il est inutile que la Cour envisage, fcomme il l’a

proposé, la nomination d’un expert ou d’une commission en vue df’éva -
luer l’étendue des dommages et la chaîne de leur causalité.
227. En outre, la Cour considère que la demande du Nicaragua tendant
à ce qu’elle ordonne au Costa Rica de s’abstenir d’entreprenfdre tout nou-
veau projet dans la région frontalière sans avoir réalisé une évaluation

appropriée de l’impact sur l’environnement (conclusions finalefs, point 3 i))
doit être rejetée. Comme elle l’a dit au paragraphe 173 ci-dessus, l’obligation
du Costa Rica d’effectuer une évaluation de l’impact sur l’efnvironnement ne
vaut que pour les activités comportant un risque de dommage transfronftière
important, et il n’y a pas lieu de supposer que le Costa Rica ne se confor -
mera pas aux obligations lui incombant en vertu du droit international,

telles qu’énoncéesdans le présent arrêt, dans le cadre des activités qu’il pou-fr
rait mener à l’avenir dans la région, y compris de nouveaux trafvaux routiers.

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tory; and its obligations under general international law and the relevant
environmental treaties (final submissions, para. 1 ; see paragraph 52

above).
In the light of its reasoning above, the Court’s declaration that
Costa Rica violated its obligation to conduct an environmental impact
assessment is the appropriate measure of satisfaction for Nicaragua.

225. Secondly, Nicaragua asks the Court to order that Costa Rica
“[c]ease all its continuing internationally wrongful acts that affectf or are
likely to affect the rights of Nicaragua” (ibid., para. 2 (i)).

The Court considers that Costa Rica’s failure to conduct an environ-
mental impact assessment does not at present adversely affect the rightsf

of Nicaragua nor is it likely further to affect them. Consequently, therfe
are no grounds to grant the remedy requested.

226. Thirdly, Nicaragua requests the Court to order Costa Rica to
restore to the extent possible the situation that existed before the road

was constructed, and to provide compensation for the damage caused
insofar as it is not made good by restitution (ibid., para. 2 (ii) and (iii)).
The Court recalls that restitution and compensation are forms of repara -
tion for material injury. The Court notes that, although Costa Rica did
not comply with the obligation to conduct an environmental impact

assessment, it has not been established that the construction of the road
caused significant harm to Nicaragua or was in breach of other substan -
tive obligations under international law. As such, restoring the originafl
condition of the area where the road is located would not constitute an f
appropriate remedy for Costa Rica’s breach of its obligation to carry out
an environmental impact assessment (see Pulp Mills on the River Uruguay

(Argentina v. Uruguay), Judgment, I.C.J. Reports 2010 (I), p. 103,
para. 271). For the same reasons, the Court declines to grant Nicaragua’s f
claim for compensation.
In view of Nicaragua’s failure to prove that significant harm was
caused, the Court does not need to consider the appointment of an expertf

or committee to evaluate the extent of harm and the chain of causation, f
as Nicaragua suggests.
227. The Court further considers that Nicaragua’s request to order
Costa Rica not to undertake any future development in the border area
without an appropriate environmental impact assessment (final submis -

sions, para. 3 (i)) must be rejected. As the Court stated in paragraph 173
above, Costa Rica’s obligation to conduct an environmental impact
assessment only applies to activities carrying a risk of significant trafns -
boundary harm, and there is no reason to suppose that Costa Rica will
not comply with its obligations under international law, as outlined in f
this Judgment, as it conducts any future activities in the area, includifng

further construction works on the road.

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228. En conclusion, la Cour constate que le Costa Rica a entrepris la
réalisation de travaux d’atténuation en vue de diminuer les efffets préjudi-
ciables que la construction de la route a pu avoir sur l’environnemenft.
Elle s’attend à ce que le Costa Rica poursuive ces efforts en conformité

avec l’obligation qui est la sienne de faire preuve de la diligence rfequise et
d’assurer une surveillance continue des effets du projet sur l’envfironne -
ment. Elle tient par ailleurs à rappeler l’importance d’une coofpération
continue entre les Parties dans l’exécution des obligations qui lefur

incombent respectivement en ce qui concerne le fleuve San Juan.

*
* *

229. Par ces motifs,

La Cour,

1) Par quatorze voix contre deux,

Dit que le Costa Rica a souveraineté sur le « territoire litigieux», tel que
défini par la Cour aux paragraphes 69-70 du présent arrêt ;

pour: M. Abraham, président; M.Yusuf, vice‑président; MM.Owada,
Tomka, Bennouna, Cançado Trindade, Greenwood, M mes Xue, Donoghue,
M. Gaja, M me Sebutinde, MM. Bhandari, Robinson, juges; M. Dugard,
juge ad hoc;
contre: M. Gevorgian, juge M; Guillaume, juge ad hoc;

2) A l’unanimité,

Dit que, en creusant trois caños et en établissant une présence militaire

sur le territoire costa -ricien, le Nicaragua a violé la souveraineté territo -
riale du Costa Rica;

3) A l’unanimité,

Dit que, en creusant deux caños en 2013 et en établissant une présence
militaire sur le territoire litigieux, le Nicaragua a violé les obligations aux-
quelles il était tenu en vertu de l’ordonnance en indication de mefsures
conservatoires rendue par la Cour le 8 mars 2011 ;

4) A l’unanimité,

Dit que, pour les motifs exposés aux paragraphes 135 -136 du présent
arrêt, le Nicaragua a violé les droits de navigation sur le fleufve San Juan

qui ont été conférés au Costa Rica par le traité de limites de 1858 ;
5) a) A l’unanimité,

Dit que le Nicaragua a l’obligation d’indemniser le Costa Rica à raison

des dommages matériels qu’il lui a causés par les activités fillicites aux -
quelles il s’est livré sur le territoire costa -ricien;

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228. To conclude, the Court notes that Costa Rica has begun mitiga -

tion works in order to reduce the adverse effects of the construction off the
road on the environment. It expects that Costa Rica will continue to pur-
sue these efforts in keeping with its due diligence obligation to monitofr
the effects of the project on the environment. It further reiterates thef
value of ongoing co -operation between the Parties in the performance of

their respective obligations in connection with the San Juan River.

*
* *

229. For these reasons,

The Court,
(1) By fourteen votes to two,

Finds that Costa Rica has sovereignty over the “disputed territory”, as
defined by the Court in paragraphs 69-70 of the present Judgment ;

in favour : President Abraham; Vice‑President Yusuf; Judges Owada,
Tomka, Bennouna, Cançado Trindade, Greenwood, Xue, Donoghue,
Gaja, Sebutinde, Bhandari, Robinson Judge ad hoc Dugard ;

against: Judge Gevorgian; Judge ad hoc Guillaume ;

(2) Unanimously,

Finds that, by excavating three caños and establishing a military pres -
ence on Costa Rican territory, Nicaragua has violated the territorial sov -

ereignty of Costa Rica;
(3) Unanimously,

Finds that, by excavating two caños in 2013 and establishing a military
presence in the disputed territory, Nicaragua has breached the obligatiofns

incumbent upon it under the Order indicating provisional measures issuedf
by the Court on 8 March 2011 ;

(4) Unanimously,

Finds that, for the reasons given in paragraphs 135-136 of the present
Judgment, Nicaragua has breached Costa Rica’s rights of navigation on
the San Juan River pursuant to the 1858 Treaty of Limits ;

(5) (a) Unanimously,

Finds that Nicaragua has the obligation to compensate Costa Rica for
material damages caused by Nicaragua’s unlawful activities on
Costa Rican territory ;

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b) A l’unanimité,

Décide que, au cas où les Parties ne pourraient se mettre d’accord à fce
sujet dans un délai de 12 mois à compter de la date du présent arrêt, elle
procédera, à la demande de l’une des Parties, au règlement dfe la question

de l’indemnisation due au Costa Rica, et réserve à cet effet la suite de la
procédure en l’affaire relative à Certaines activités menées par le Nicara ‑
gua dans la région frontalière (Costa Rica c. Nicaragua);

c) Par douze voix contre quatre,

Rejette la demande du Costa Rica tendant à ce que le Nicaragua soit
condamné à payer certains frais de procédure ;

pour: M. Abraham, président; M.Yusuf, vice‑président; MM.Owada, Ben-
nouna, Cançado Trindade, M mesXue, Donoghue, MM. Gaja, Bhandari ,
Robinson, Gevorgian, juges; M. Guillaume, juge ad hoc;
contre: MM. Tomka, Greenwood, M meSebutinde, juges; M.Dugard, juge

ad hoc;
6) A l’unanimité,

Dit que le Costa Rica, en omettant d’effectuer une évaluation de l’im -

pact sur l’environnement en ce qui concerne la construction de la roufte
1856, a violé l’obligation qui lui incombait au titre du droit intfernational
général ;

7) Par treize voix contre trois,

Rejette le surplus des conclusions soumises par les Parties.
pour: M. Abraham, président; M.Yusuf, vice‑président; MM.Owada,
mes
Tomka, Bennmena, Cançado Trindade, Greenwood, M Xue, Donoghue,
M. Gaja, M Sebutinde, M. Gevorgian, juges; M. Guillaume, juge adhoc;
contre: MM. Bhandari, Robinson, juges ; M.Dugard, juge ad hoc.

Fait en français et en anglais, le texte français faisant foi, au Palais de
la Paix, à La Haye, le seize décembre deux mille quinze, en trois exem -
plaires, dont l’un restera déposé aux archives de la Cour et lefs autres
seront transmis, respectivement, au Gouvernement de la République du f

Costa Rica et au Gouvernement de la République du Nicaragua.

Le président,

(Signé) Ronny Abraham.

Le greffier,

(Signé) Philippe Couvreur.

M. le juge Yusuf, vice -président, joint une déclaration à l’arrêt ; M. le
juge Owada joint à l’arrêt l’exposé de son opinion individuelle ; MM. les
me
juges Tomka et Greenwood, M la juge Sebutinde et M. le juge ad hoc

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5 Ord 1088.indb 156 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 741

(b) Unanimously,

Decides that, failing agreement between the Parties on this matter
within 12 months from the date of this Judgment, the question of com -
pensation due to Costa Rica will, at the request of one of the Parties, be
settled by the Court, and reserves for this purpose the subsequent procef -
dure in the case concerning Certain Activities Carried Out by Nicaragua in

the Border Area (Costa Rica v. Nicaragua);

(c) By twelve votes to four,
Rejects Costa Rica’s request that Nicaragua be ordered to pay costs

incurred in the proceedings ;
in favour : President Abraham; Vice‑President Yusuf; Judges Owada, Ben -
nouna, Cançado Trindade, Xue, Donoghue, Gaja, Bhandari, Robinson,
Gevorgian ; Judge ad hoc Guillaume ;

against: Judges Tomka, Greenwood, Sebutinde Judge;ad hoc Dugard ;

(6) Unanimously,
Finds that Costa Rica has violated its obligation under general interna-

tional law by failing to carry out an environmental impact assessment
concerning the construction of Route 1856 ;

(7) By thirteen votes to three,

Rejects all other submissions made by the Parties.
in favour : President Abraham; Vice‑President Yusuf; Judges Owada,
Tomka, Bennouna, Cançado Trindade, Greenwood, Xue, Donoghue,

Gaja, Sebutinde, Gevorgian Judge ad hoc Guillaume ;
against: Judges Bhandari, Robinson Jud;e ad hoc Dugard.

Done in French and in English, the French text being authoritative, at

the Peace Palace, The Hague, this sixteenth day of December, two thou -
sand and fifteen, in three copies, one of which will be placed in the
archives of the Court and the others transmitted to the Government of
the Republic of Costa Rica and the Government of the Republic of Nica-

ragua, respectively.

(Signed) Ronny Abraham,

President.
(Signed) Philippe Couvreur,

Registrar.

Vice-President Yusuf appends a declaration to the Judgment of the
Court ; JudgeOwada appends a separate opinion to the Judgment of the
Court; Judges Tomka, Greenwood, Sebutifnde and Judge ad hoc

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5 Ord 1088.indb 157 19/10/16 12:01 742 certaines activitésf et construction d’unfe route (arrêt)

Dugard joignent à l’arrêt une déclaration commune; M. le juge Cançado
Trindade joint à l’arrêt l’exposé de son opinion individuelle; M me la juge
Donoghue joint à l’arrêt l’exposé de son opinion individuelle ; M. le juge
Bhandari joint à l’arrêt l’exposé de son opinion individuelle ;

M. le juge Robinson joint à l’arrêt l’exposé de son opinion individuelle ;
M. le juge Gevorgian joint une déclaration à l’arrêt ; M. le juge ad hoc
Guillaume joint une déclaration à l’arrêt ; M. le juge ad hoc Dugard
joint à l’arrêt l’exposé de son opinion individuelle.

(Paraphé) R.A.

(Paraphé) Ph.C.

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5 Ord 1088.indb 158 19/10/16 12:01 certain activities afnd construction of a rfoad (judgment) 742

Dugard append a joint declaration to the Judgment of the Court ; Judge

Cançado Trindade appends a separate opinion to the Judgment of the
Court; Judge Donoghue appends a separate opinion to the Judgment of
the Court ; Judge Bhandari appends a separate opinion to the Judgment
of the Court ; Judge Robinson appends a separate opinion to the
Judgment of the Court ; Judge Gevorgian appends a declaration to the

Judgment of the Court ; Judge ad hoc Guillaume appends a declaration
to the Judgment of the Court ; Judge ad hoc Dugard appends a separate
opinion to the Judgment of the Court.

(Initialled) R.A.

(Initialled)Ph.C.

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5 Ord 1088.indb 159 19/10/16 12:01

ICJ document subtitle

Merits

Document file FR
Document Long Title

Judgment of 16 December 2015

Links