Separate opinion of Judge Xue

SEPARATE OPINION OF JUDGE XUE
TABLE OF CONTENTS
Paragraphs
I. PROCEDURAL FAIRNESS FOR THE GOOD ADMINISTRATION OF JUSTICE 2-9
II. SUBSTANTIVE ISSUES IN THE PRESENT CASE 10-49
A. Continental shelf under customary international law as reflected in
Article 76 11-19
B. Relationship between the régimes of the continental shelf and of the
exclusive economic zone 20-36
C. State practice with regard to CLCS submissions 37-49
III. NICARAGUA’S SUBMISSIONS ON AN EXTENDED CONTINENTAL SHELF 50-60
1. I have voted in favour of the operative paragraph of the Judgment but on entirely different
legal grounds. I have serious reservations about the Court’s findings on the applicable law in the
present case. The legal ramifications it may exert on the régime of continental shelf are hard to tell.
I am obligated to place my position on the record.
I. PROCEDURAL FAIRNESS FOR THE GOOD
ADMINISTRATION OF JUSTICE
2. My reservation about the procedural fairness in the organization of oral proceedings has
been largely reflected in the joint declaration appended to the Order of 4 October 2022 in the present
case (Question of the Delimitation of the Continental Shelf between Nicaragua and Colombia beyond
200 Nautical Miles from the Nicaraguan Coast (Nicaragua v. Colombia), Order of 4 October 2022,
joint declaration of Judges Tomka, Xue, Robinson, Nolte and Judge ad hoc Skotnikov). With this
final decision settling the case, the oral proceedings on the merits were closed and, consequently, the
Parties did not have an oral hearing to make their final arguments on all the issues that still divided
them and to submit their final submissions to the Court. Procedurally, this practice is unprecedented
in the Court’s judicial history.
3. According to Article 48 of the Statute, the Court shall make orders for the conduct of the
case and decide the form and time in which each party must conclude its arguments. This power,
however, must be exercised in accordance with the principle of juridical propriety for the good
administration of justice. Article 31 of the Rules of Court provides that “[i]n every case submitted to
the Court, the President shall ascertain the views of the parties with regard to questions of procedure”.
Procedurally, the Court must ensure that each party is free to choose and follow its own judicial
strategy and to fully develop all its arguments. In this regard, the Court should exercise great caution
when controlling the oral proceedings so as to avoid jeopardizing the rights of the parties (ibid.,
para. 11, note 3, citing Mohammed Bedjaoui, “The ‘Manufacture’ of Judgments at the International
Court of Justice”, Pace Yearbook of International Law, 1991, Vol. 3, p. 44; Eduardo Jiménez de
Aréchaga, “The Amendments to the Rules of Procedure of the International Court of Justice”,
American Journal of International Law, 1973, Vol. 67 (1), p. 7).
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4. In its final written pleadings, Nicaragua has made three submissions. The first submission
concerns maritime delimitation between the continental shelf beyond 200 nautical miles (also
referred to as the “extended continental shelf”) as claimed by Nicaragua and Colombia’s maritime
area within 200 nautical miles from Colombia’s mainland baselines. The second and third
submissions relate to the maritime entitlements of Colombia’s maritime features that may overlap
with Nicaragua’s entitlement to an extended continental shelf. Apparently, Nicaragua’s submissions
concern both maritime entitlements of the Parties and delimitation. The legal questions posed by the
Court in the 4 October 2022 Order primarily address the issue of entitlement. Without hearing the
Parties on all the issues, both in law and in fact, and without making the entire case file accessible to
the public, the judicial process did not fully run its course. This is particularly questionable when the
Applicant has specifically requested the Court to proceed to a hearing on the merits.
5. Procedurally, even supposing that the answers to the legal questions were decisive for the
resolution of the whole case, the present approach adopted by the Court at this phase should still be
called into question. As the Applicant indicated, the legal questions posed by the Court had already
been substantially argued by the Parties in the course of the written proceedings of this case and
during the Territorial and Maritime Dispute (Nicaragua v. Colombia) case.
6. The first legal question posed by the Court initially arose from Nicaragua’s submission I (3)
in the Territorial and Maritime Dispute case, where Nicaragua requested the Court to define “a
continental shelf boundary dividing by equal parts the overlapping entitlements to a continental shelf
of both Parties”, which means that Nicaragua’s claim to a continental shelf extends beyond
200 nautical miles, as the distance between the mainland coasts of the Parties extends more than
400 nautical miles (Nicaragua v. Colombia, Judgment, I.C.J. Reports 2012 (II) (hereinafter the
“2012 Judgment”), p. 636, para. 17). The Court rejected Nicaragua’s request for the delimitation of
its extended continental shelf with Colombia’s maritime entitlements on the ground that Nicaragua
had not established that it has a continental margin that extends far enough to overlap with
Colombia’s 200-nautical-mile entitlement to the continental shelf, measured from Colombia’s
mainland coast. The Court stated that it was not in a position to delimit the continental shelf boundary
between Nicaragua and Colombia, as requested by Nicaragua, even using the general formulation
proposed by it (ibid., p. 669. para. 129). In this regard, the Court especially mentioned that it saw no
need to address the issue raised by the Parties as to whether a delimitation of overlapping entitlements
which involves an extended continental shelf of one State can affect a 200-nautical-mile entitlement
to the continental shelf of another State (ibid., pp. 669-670, paras. 129-130), a legal question that the
Court now considers has been answered by customary international law.
7. Moreover, during the oral proceedings in that case, Judge Bennouna posed the following
questions to the Parties:
 “Is the legal régime of the continental shelf for the portion located within the 200-nautical-mile
limit different from that for the portion located beyond this limit?”
 “Can the rules laid down in Article 76 of the 1982 United Nations Convention on the Law of the
Sea concerning the determination of the outer limit of the continental shelf beyond 200 nautical
miles today be considered as rules of customary international law?”
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In answering Judge Bennouna’s questions, the Parties went some way in answering the first question
posed by the Court in the Order of 4 October 2022 and gave their views on the criteria under
customary international law for the determination of the limit of the continental shelf beyond
200 nautical miles.
8. At the preliminary objections phase in the present case, Colombia contended that
Nicaragua’s first submission was a “reincarnation” of Nicaragua’s claim contained in its final
submission I (3) in the Territorial and Maritime Dispute case, in so far as it concerned delimitation
of extended continental shelf. It argued that, by virtue of res judicata, the Court was prevented from
entertaining it in the present case. The Court rejected Colombia’s objections, including its claim
based on res judicata, and upheld the admissibility of Nicaragua’s first submission. During the
written proceedings, the Parties significantly developed their arguments on Nicaragua’s entitlement
to an extended continental shelf and its relationship with Colombia’s entitlements within 200 nautical
miles.
9. From a procedural point of view, there seems to be no sound reason for the Court to depart
from its established practice by holding an oral proceeding to hear the views of the Parties only on
two legal questions. The Parties could have addressed them together with the factual and other legal
aspects of the case during the oral proceedings on the merits. If the settlement of the dispute between
the Parties on Nicaragua’s entitlement to an extended continental shelf indeed hinges entirely on the
answers to the legal questions, as recalled above, the matter should have been resolved much earlier
for the sake of judicial economy. As a judicial organ, the Court is supposed to know the law 
iura novit curia  and apply it to settle a dispute whenever it is called for. If the Court considers
that, under customary international law, maritime entitlements within 200 nautical miles of one State
take precedence over an extended continental shelf of another State, it should have decided, either in
the 2012 Judgment in the Territorial and Maritime Dispute case or in the Judgment of 17 March
2016 on preliminary objections in the present case (hereinafter the “2016 Judgment”), that, by virtue
of customary international law, Nicaragua’s claim of an extended continental shelf should be rejected
outright because Nicaragua is not entitled to such a claim and consequently no issue of delimitation
arises between the Parties. The dispute would thus have been settled there. Having unduly prolonged
the judicial process and having left unexamined all the technical and scientific evidence submitted
by the Parties, the Court’s approach, for whatever reason, cannot be deemed in conformity with the
principles of judicial propriety and has doubtfully facilitated judicial economy.
II. SUBSTANTIVE ISSUES IN THE PRESENT CASE
10. I agree with the majority that the negotiation and conclusion of the United Nations
Convention on the Law of the Sear (hereinafter “UNCLOS”) has, to a large extent, codified and
contributed to the progressive development of customary international law of the sea. However, I do
not share the reasoning given in the Judgment on the contemporary régime of the continental shelf.
The legal issue before the Court ultimately boils down to a question that often arises in continental
shelf delimitation, namely, the relationship between the extended continental shelf of one State and
maritime entitlements within 200 nautical miles from the baselines of another State. It bears on the
fundamental concept of natural prolongation in contemporary customary international law and the
“package deal” that was negotiated and eventually worked out at the Third United Nations
Conference on the Law of the Sea (hereinafter the “Law of the Sea Conference”). The reasoning of
the Judgment on the current state of the law, in my view, is neither persuasive nor reflective of general
State practice and opinio juris.
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A. Continental shelf under customary international law
as reflected in Article 76
11. The first question that the Court posed to the Parties in the Order of 4 October 2022
(hereinafter the “first question”) reads as follows:
“(1) Under customary international law, may a State’s entitlement to a continental
shelf beyond 200 nautical miles from the baselines from which the breadth of its
territorial sea is measured extend within 200 nautical miles from the baselines of another
State?”
This question basically asks an issue of entitlement on the basis of the relationship between two
criteria as set forth in Article 76, paragraph 1, of UNCLOS. If the two criteria are of equal
applicability, Nicaragua may be entitled to an extended continental shelf which overlaps with
Colombia’s entitlements within 200 nautical miles, provided its physical existence is established.
The case then calls for delimitation. If the answer to the question is in the negative, it means that the
distance criterion takes precedence over natural prolongation. Colombia’s 200-nautical-mile
entitlements prevail over Nicaragua’s claim; Nicaragua is not entitled to an extended continental
shelf that extends within 200 nautical miles of Colombia. Consequently, there is no issue of
delimitation between the Parties. The answer to the first question apparently has to be found in
customary international law.
12. Under customary international law, the continental shelf régime originates from the
concept of natural prolongation. The doctrine of the continental shelf was first recalled by the Court
in the North Sea Continental Shelf cases (North Sea Continental Shelf (Federal Republic of
Germany/Denmark; Federal Republic of Germany/Netherlands), Judgment, I.C.J. Reports 1969,
pp. 32-33, para. 47), in which the Court considered that the essential basis of the continental shelf is
the extended sovereign rights of the coastal State over the natural prolongation or continuation of its
land territory under the sea. Such rights exist ipso facto and ab initio (ibid., p. 22, para. 19). This
pronouncement was reiterated by the Court in subsequent cases. In the Tunisia/Libyan Arab
Jamahiriya case, for example, the Court stated that
“[t]he concept of natural prolongation . . . was and remains a concept to be examined
within the context of customary law and State practice. While the term ‘natural
prolongation’ may have been novel in 1969, the idea to which it gave expression was
already a part of existing customary law as the basis of the title of the coastal State.”
(Continental Shelf (Tunisia/Libyan Arab Jamahiriya), Judgment, I.C.J. Reports 1982,
p. 46, para. 43.)
13. Admittedly, contemporary customary international law on the definition of the continental
shelf was much influenced by the negotiations of the Law of the Sea Conference that lasted for nine
years. Not long after the Court delivered its Judgment in the North Sea Continental Shelf cases, the
United Nations General Assembly adopted a resolution in which it was stated
“that the definition of the continental shelf contained in the Convention on the
Continental Shelf of [1958] does not define with sufficient precision the limits of the
area over which a coastal State exercises sovereign rights for the purpose of exploration
and exploitation of natural resources, and that customary international law on the
subject is inconclusive” (resolution 2574 (XXIV) of 15 December 1969, adopted with
65 votes in favour, 12 against, and 30 abstentions; emphasis added).
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This resolution was adopted against the backdrop of the upcoming negotiations on the law of the sea
and growing concern over the prospects of deep sea-bed mining. The definition found in Article 1 of
the 1958 Convention did not provide a definitive limit of continental margin, leaving it open to
technical exploitability. The relevant article reads as follows:
“For the purpose of these articles, the term ‘continental shelf’ is used as referring
(a) to the seabed and subsoil of the submarine areas adjacent to the coast but outside the
area of the territorial sea, to a depth of 200 metres or, beyond that limit, to where the
depth of the superjacent waters admits of the exploitation of the natural resources of the
said areas; (b) to the seabed and subsoil of similar submarine areas adjacent to the coasts
of islands.”
Apparently, when the United Nations General Assembly disapproved of this definition as imprecise,
the focus of its attention was on the limits of the continental shelf but not its foundation; it was feared
that by recognizing an exploitability criterion, coastal States may, with the continuous advancement
of technology and science, extend their claim unrestrictedly, thus encroaching upon the common area
of the deep sea-bed and its resources, which were subsequently proclaimed as the “common heritage
of mankind” at the Law of the Sea Conference. It was this common interest that eventually led to the
new regulation of the continental shelf régime under Part VI of UNCLOS.
14. The outcome of the negotiations on Part VI of UNCLOS is a balanced solution between
the individual interest of coastal States and the common interest of the international community.
From the text of Part VI, it is not difficult to observe that the fundamental basis of the continental
shelf régime remains intact under the “package deal”; natural prolongation as the physical criterion
for the determination of the continental shelf is not replaced by a distance criterion, the criterion
applicable to the régime of the exclusive economic zone. There is no basis in customary international
law to suggest that restrictions imposed on the extent and use of the continental shelf beyond
200 nautical miles imply that the continental shelf is now under two régimes: the régime of
continental shelf within 200 nautical miles and the régime of the extended continental shelf. Either
based on the natural prolongation of its land territory or a distance of 200 nautical miles, every coastal
State is entitled to a single continental shelf; the substantive rights of the coastal State in the
continental shelf within and beyond 200 nautical miles from the baselines are generally the same,
which is affirmed by subsequent judicial and arbitral decisions, including the present Judgment
(Delimitation of the maritime boundary in the Bay of Bengal (Bangladesh/Myanmar), Judgment,
ITLOS Reports 2012, p. 96, para. 361; Bay of Bengal Maritime Boundary Arbitration (Bangladesh v.
India), Award of 7 July 2014, United Nations, Reports of International Arbitral Awards (RIAA),
Vol. XXXII, p. 38, para. 77; the present Judgment, para. 75).
15. The equal relationship between the two criteria can be further observed from the text of
Article 76, paragraph 1, which is considered by the Court as reflective of customary international
law (Territorial and Maritime Dispute (Nicaragua v. Colombia), Judgment, I.C.J. Reports 2012 (II),
p. 666, para. 118).
Article 76, paragraph 1, provides:
“The continental shelf of a coastal State comprises the sea-bed and subsoil of the
submarine areas that extend beyond its territorial sea throughout the natural
prolongation of its land territory to the outer edge of the continental margin, or to a
distance of 200 nautical miles from the baselines from which the breadth of the
territorial sea is measured where the outer edge of the continental margin does not
extend up to that distance”.
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By virtue of this provision, a distance criterion is added alongside the natural prolongation criterion
to the definition of the continental shelf. A coastal State whose continental margin does not extend
up to 200 nautical miles may extend its entitlement to 200 nautical miles, irrespective of geological
and other geophysical conditions. This entitlement provision, by its ordinary meaning, nowhere
indicates that the two criteria apply respectively to two distinct parts of the continental shelf, that is
to say, that the distance criterion applies to the continental shelf within 200 nautical miles while
natural prolongation criterion is only applicable to the extended continental shelf, as suggested in the
Judgment (para. 75). For any single continental shelf, it may be defined by either one of the criteria,
depending on the physical circumstances of the continental margin concerned. Between the two
criteria, there is neither priority nor precedence (Delimitation of the maritime boundary between
Guinea and Guinea-Bissau (Guinea/Guinea-Bissau), Award of 14 February 1985, RIAA, Vol. XIX,
p. 191, para. 116). If the distance criterion were indeed given precedence over natural prolongation
within 200 nautical miles, the text of Article 76, paragraph 1, must have been written differently to
indicate such a hierarchy, because it would otherwise annul the entitlement to certain extended
continental shelves that coastal States enjoy ipso facto and ab initio and would fundamentally change
the basis of continental shelf entitlements under customary international law. Apparently, no such
understanding can be found in the text of Article 76.
16. In analysing the terms of the continental shelf under Article 76, the Court infers an
assumption of negotiating States from the mechanism established under Article 76, paragraph 8, of
UNCLOS that an extended continental shelf would only extend into maritime areas that would
otherwise be located in the “Area”, hence denying the possibility that an extended continental shelf
of one State may extend within 200 nautical miles from the baselines of another State (Judgment,
para. 76). In this regard, it refers to Article 82 on payments and contributions to the International
Seabed Authority in respect of exploitation of the non-living resources of the extended continental
shelf and states that “[s]uch a payment would not serve the purpose of this provision in a situation
where the extended continental shelf of one State extended within 200 nautical miles from the
baselines of another State”. Furthermore, it observes that the issue before the Court with regard to
the extended continental shelf of one State extending within 200 nautical miles of another State “was
not debated” during the Law of the Sea Conference (Judgment, para. 76).
17. In the present case, Nicaragua’s claim obviously does not concern the Area, nor did the
Parties refer to it during the proceedings. It is true that the limitation on the continental shelf beyond
200 nautical miles and the Article 82 mechanism are designed to protect the Area and its resources
as the common heritage of mankind, but they are irrelevant to the present situation. It is questionable
whether an inference could be drawn from this treaty mechanism that the distance criterion was
provided as the primary entitlement to a continental shelf within 200 nautical miles to trump an
overlapping entitlement based on natural prolongation. The assumption inferred from Articles 76
and 82 of UNCLOS, even if established, does not necessarily lead to the conclusion that the
mechanism under Article 82 has the consequential effect of restricting a State’s entitlement to an
extended continental shelf from extending within 200 nautical miles of another State. What has been
agreed by the States in the “package deal” remains in the text of the treaty. What is not included
should continue to be governed by customary international law. The absence of discussions of the
issue during the negotiations at the Law of the Sea Conference does not reinforce the Court’s
reasoning. On the contrary, that fact weakens it. The negotiating parties did not debate the issue
simply because they saw no need to do so. As is observed,
“[t]he establishment of a maritime area in which the States concerned have shared rights
is not unknown under the Convention. The Convention is replete with provisions that
recognize to a greater or lesser degree the rights of one State within the maritime zones
of another.” (Bay of Bengal Maritime Boundary Arbitration (Bangladesh v. India),
Award of 7 July 2014, RIAA, Vol. XXXII, pp. 148-149, para. 507.)
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Overlapping continental shelf entitlements based on different criteria could well have been envisaged
when the distance criterion was introduced into Article 76, paragraph 1. Unless otherwise provided,
a hierarchical relationship between the two criteria cannot be construed from the simple fact that
there are a very large number of States parties to UNCLOS. Moreover, to what extent the relevant
treaty rules have passed into the corpus of customary international law is still a question to be
determined under customary international law. In other words, the Court has to ascertain whether
there is a general State practice and acceptance of such practice as law (opinio juris) that support a
customary rule as identified by the Court. In this regard, “two conditions must be fulfilled. Not only
must the acts concerned amount to a settled practice, but they must also be such, or be carried out in
such a way, as to be evidence of a belief that this practice is rendered obligatory by the evidence of
a rule of law requiring it.” (North Sea Continental Shelf (Federal Republic of Germany/Denmark;
Federal Republic of Germany/Netherlands), Judgment, I.C.J. Reports 1969, p. 44, para. 77; see also
Conclusions 2 and 9 of the Draft conclusions on identification of customary international law, with
commentaries, adopted by the International Law Commission in 2018 (hereinafter “ILC
Conclusions”, UN doc. A/73/10, pp. 122-156).
18. In determining the existence and content of a customary rule that may have evolved from
a treaty rule, the Court in the North Sea Continental Shelf cases highlighted an indispensable
requirement for the consideration of the State practice under the treaty rule concerned, according to
which,
“State practice, including that of States whose interests are specially affected, should
have been both extensive and virtually uniform in the sense of the provision invoked; —
and should moreover have occurred in such a way as to show a general recognition that
a rule of law or legal obligation is involved” (North Sea Continental Shelf (Federal
Republic of Germany/Denmark; Federal Republic of Germany/Netherlands),
Judgment, I.C.J. Reports 1969, p. 43, para. 74).
In assessing the evidence, regard must be had to the overall context, the nature of the rule and the
particular circumstances in which the evidence in question is to be found (Conclusion 3 of the ILC
Conclusions).
19. In assessing these two constitutive elements for the identification of a customary rule, the
Court relies heavily on the relationship of the régimes of the exclusive economic zone and of the
continental shelf as provided for in Article 56, paragraph 3, of UNCLOS and on States parties’
submissions to the Commission on the Limits of the Continental Shelf (hereinafter the “CLCS” or
“Commission”). It is this part of the reasoning that I find most unpersuasive and problematic. It flies
in the face of State practice and well-settled jurisprudence of the Court.
B. Relationship between the régimes of the continental shelf
and of the exclusive economic zone
20. In recalling the negotiating history of UNCLOS, the Court refers to the relationship
between the régimes of the exclusive economic zone and of the continental shelf. In the Court’s view,
since a coastal State enjoys in the exclusive economic zone, inter alia, sovereign rights over the
non-living resources in the sea-bed and subsoil within 200 nautical miles and since such rights shall
be exercised in accordance with the rules applicable to the continental shelf, the two régimes are
interrelated. Based on that link, the Court assumed that the entitlement to an extended continental
shelf may not extend within 200 nautical miles because such an extension would encroach on the
attendant exclusive economic zone of the coastal State. This inference, in my view, overstates the
import of Article 56, paragraph 3.
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21. First of all, the interrelationship between the régimes of the exclusive economic zone and
of the continental shelf as provided for in Article 56 does not give a prevailing effect to the exclusive
economic zone over the continental shelf. While Article 56, paragraph 3, links the two zones, it does
not go so far as to say that the two zones are inseparable in maritime delimitation and that maritime
entitlements within 200 nautical miles by their very nature shall take precedence over an extended
continental shelf entitlement. States’ positions as well as their practice are divided on the question
whether the two criteria under Article 76, paragraph 1, are of equal applicability or hierarchical in
effect. They differ as to whether the water column and the sea-bed within 200 nautical miles may be
delimited separately. Among scholars, views on the subject-matter also vary greatly1. This is indeed
an area that the “package deal” was ambiguous about. On the relationship between the two régimes,
one analysis of Article 56, paragraph 3, is pertinent in the present context:
“The text of Article 56 (3) is a clear indication of the applicable law, which might
result from the idea that the continental shelf and the EEZ are essentially dealing with
different natural resources. Whereas the continental shelf confers on coastal States
exclusive rights over the exploration and exploitation of the non-living resources and
sedentary resources in the seabed and subsoil, the EEZ is more concerned with living
resources in the water column, in particular fisheries. It is therefore in line with the
functional purposes of the two regimes if the continental shelf regime applies to the
seabed and subsoil, even if the area is within the reach of the EEZ.”2
This understanding is consistent with the concept of a single continental shelf. The continental shelf
régime applies to the sea-bed and subsoil irrespective of the basis of the entitlement, natural
prolongation or distance. While the inclusion of the sovereign rights over the sea-bed and subsoil in
the régime of the exclusive economic zone may reinforce the continental shelf entitlement within
200 nautical miles, Article 56, by its own terms, only concerns the content and exercise of substantive
rights.
22. Judicial and arbitral decisions generally recognize the autonomy and distinction of the two
régimes. In the present case, however, the Court draws a different reading from its 1985 Judgment
in the Continental Shelf (Libyan Arab Jamahiriya/Malta) case, where the Court observed that,
“[a]lthough there can be a continental shelf where there is no exclusive economic zone, there cannot
be an exclusive economic zone without a corresponding continental shelf” (Judgment, I.C.J. Reports
1985, p. 33, para. 34). Based on this statement, the Court now considers that, with the distance
criterion as the sole basis of entitlement of the coastal State to both the exclusive economic zone and
the continental shelf within 200 nautical miles, an extended continental shelf of one State may not
extend within 200 nautical miles of another State.
23. This finding, first of all, implies that, with the distance criterion applicable to both régimes,
the concept of the continental shelf within 200 nautical miles has been absorbed by that of the
exclusive economic zone under the contemporary law of the sea, an implication that the Court
categorically rejected in the same Judgment (see ibid., p. 33, para. 33). Following the above
statement cited by the Court, the Court in that case went on stating that,
1 Malcolm D. Evans, “Delimitation and the Common Maritime Boundary”, British Yearbook of International Law,
1994, Vol. 64 (1), p. 283; Xuexia Liao, “Is There a Hierarchical Relationship between Natural Prolongation and Distance
in the Continental Shelf Delimitation?”, The International Journal of Marine and Coastal Law, 2018, Vol. 33, pp. 105-110.
2 Xuexia Liao, “Is There a Hierarchical Relationship between Natural Prolongation and Distance in the Continental
Shelf Delimitation?”, The International Journal of Marine and Coastal Law, 2018, Vol. 33, pp. 106-107.
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“for juridical and practical reasons, the distance criterion must now apply to the
continental shelf as well as to the exclusive economic zone; and this quite apart from
the provision as to distance in paragraph 1 of Article 76. This is not to suggest that the
idea of natural prolongation is now superseded by that of distance. What it does mean
is that where the continental margin does not extend as far as 200 miles from the shore,
natural prolongation . . . is in part defined by distance from the shore, irrespective of the
physical nature of the intervening sea-bed and subsoil. The concepts of natural
prolongation and distance are therefore not opposed but complementary; and both
remain essential elements in the juridical concept of the continental shelf.” (Continental
Shelf (Libyan Arab Jamahiriya/Malta), Judgment, I.C.J. Reports 1985, p. 33, para. 34;
emphasis added.)
This statement shows that the interrelationship between the two régimes as defined in Article 56,
paragraph 3, is not conclusive on the question that the Court is dealing with in the present case,
namely, whether there is priority accorded to the entitlement within 200 nautical miles over an
extended continental shelf. Moreover, the factual situation of that case is entirely different from the
present one. In the former, the distance between the parties is less than 400 nautical miles, where
geographical or geophysical factors could be disregarded, while in the latter, the Applicant’s claim
to an extended continental shelf depends on the technical and scientific evidence that may establish
the existence of the natural prolongation of its land territory. Once the natural prolongation is
established, the Applicant is entitled to the extended continental shelf. What the Court stated in the
context of the Libyan Arab Jamahiriya/Malta case did not address the question of entitlement but of
delimitation. At the time of that case, with UNCLOS not yet in force and the customary status of
Article 76, paragraph 1, with regard to the distance criterion still in doubt, the Court took the legally
permissible extent of the exclusive economic zone appertaining to a given State as “one of the
relevant circumstances to be taken into account for the delimitation of the continental shelf” of that
State (ibid., p. 33, para. 33; emphasis added). By granting greater importance to the element of
distance, which is common to both régimes, in the delimitation of continental shelf within
200 nautical miles, the Court only tried to reach an equitable solution but not to pronounce a general
rule restricting natural prolongation.
24. Even supposing that the Court’s statement in the Continental Shelf (Libyan Arab
Jamahiriya/Malta) case did constitute a general legal pronouncement, one may still wonder when
the putative rule as identified by the Court in this case formed part of customary international law,
because the judicial and arbitral decisions and State practice on the delimitation of continental shelf
subsequent to the 1985 Judgment do not support such a proposition.
25. In the Bay of Bengal cases, the International Tribunal for the Law of the Sea (ITLOS) and
the arbitral tribunal established under Annex VII of UNCLOS respectively delimited the maritime
boundary including the extended continental shelf between the parties to each case. The adjustment
of the provisional equidistance line resulted in a “grey area” of limited size in both cases, which is
located within the 200-nautical-mile limit of the coast of one party but on the other party’s side of
the line that delimits the parties’ continental shelves (Delimitation of the maritime boundary in the
Bay of Bengal (Bangladesh/Myanmar), Judgment, ITLOS Reports 2012, p. 119, para. 463; Bay of
Bengal Maritime Boundary Arbitration between Bangladesh and India, Award of 7 July 2014, RIAA,
Vol. XXXII, p. 147, para. 498). The Court dismisses the Applicant’s argument based on these cases,
which it considers irrelevant for the consideration of the present case, because, in its view, the grey
area is “an incidental result” of the adjustment of the provisional equidistance line and the
circumstances in those cases are distinct from the situation in the present case (Judgment, para. 72).
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26. In Somalia v. Kenya  a case it has recently adjudicated  the Court observed that if the
delimitation line, as determined, continues on the course beyond 200 nautical miles, it might give
rise to an area of limited size lying within 200 nautical miles of the coast of Somalia but on the
Kenyan side of the boundary, thus resulting in a similar “grey area” as in the Bay of Bengal cases
(Maritime Delimitation in the Indian Ocean (Somalia v. Kenya), Judgment, I.C.J. Reports 2021,
p. 277, para. 197). The Court again dismisses the relevance of the case, stating that the grey area is
merely a possibility and that, therefore, there is no need to take it into account (Judgment, para. 73).
27. This approach taken by the Court appears hasty and evasive. In these three cases, the “grey
area”, albeit incidental in nature and small in size, is in itself a piece of hard evidence that disproves
at least the inseparability of the two zones in the maritime delimitation. Convenient or not, it evinces
that the exclusive economic zone does not dictate the delimitation of the continental shelf. As ITLOS
observed in the Bangladesh/Myanmar case,
“the legal regime of the continental shelf has always coexisted with another legal regime
in the same area. Initially that other regime was that of the high seas and the other States
concerned were those exercising high seas freedoms. Under the Convention, as a result
of maritime delimitation, there may also be concurrent exclusive economic zone rights
of another coastal State.” (Delimitation of the maritime boundary in the Bay of Bengal
(Bangladesh/Myanmar), Judgment, ITLOS Reports 2012, p. 121, para. 475.)
Evidently, these judicial and arbitral organs do not consider that there existed a customary rule by
which an extended continental shelf of one State may not extend within the exclusive economic zone
of another State, as a matter of entitlement. When an overlap of entitlements occurs, the matter is
one of delimitation. Article 83 of UNCLOS, on purpose, leaves sufficient room for the relevant
circumstances of each case to be considered in the delimitation process.
28. In practice, States not only claim an entitlement to an extended continental shelf that may
extend within 200 nautical miles of another State, but also draw maritime boundaries by agreement
that delimit the exclusive economic zone and the continental shelf separately. They do it either by
separate agreements dealing with different zones, or simply by drawing different boundary lines
within the same agreement.
29. Australia and Indonesia, for example, concluded an agreement on the continental shelf
boundary in the Timor and Arafura Seas in 1972 (Agreement between the Government of the
Commonwealth of Australia and the Government of the Republic of Indonesia establishing certain
seabed boundaries in the area of the Timor and Arafura Seas, supplementary to the Agreement of
18 May 1971, concluded 9 October 1972, entered into force 8 November 1973, United Nations,
Treaty Series (UNTS), Vol. 974, p. 319). In 1997, the two States concluded another agreement on the
exclusive economic zone boundary and the western extension of the sea-bed boundary (Agreement
between the Government of Australia and the Government of the Republic of Indonesia establishing
an exclusive economic zone boundary and certain seabed boundaries, concluded 14 March 1997, not
yet in force, International Legal Materials, 1997, Vol. 36, p. 1053). The latter agreement drew the
continental shelf boundary on the basis of the geological and geophysical factors of the Timor
Trough, while the boundary of the exclusive economic zone was drawn on the basis of distance; the
former line is closer to the Indonesian side. As a result of these two agreements, there are several
overlapping areas where Australia’s extended continental shelf is subjacent to Indonesia’s exclusive
economic zone (see illustrative map 1). For the purpose of management, the Agreement contains a
specific provision regulating, inter alia, the rights and obligations of each party in the areas of
overlapping jurisdiction. It affirms Indonesia’s sovereign rights of exclusive economic zone in the
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water column and Australia’s sovereign rights of continental shelf in the sea-bed3. Although the
Agreement has not yet entered into force, it manifests that the parties did not consider there existed
a customary rule by which Australia could not, by law, claim its entitlement to an extended
continental shelf that extends within Indonesia’s 200 nautical miles from its baselines.
3 Article 7 of the Agreement reads as follows:
“Areas of overlapping jurisdiction
In those areas where the areas of exclusive economic zone adjacent to and appertaining to a Party
(the First Party) overlap the areas of seabed adjacent to and appertaining to a Party being the other Party
(the Second Party):
(a) the First Party may exercise exclusive economic zone sovereign rights and jurisdiction provided for in
the 1982 Convention in relation to the water column;
(b) the Second Party may exercise continental shelf sovereign rights and jurisdiction provided for in the
1982 Convention in relation to the seabed;
(c) the construction of an artificial island shall be subject to the agreement of both Parties. An ‘artificial
island’ for the purposes of this Article is an area of land, surrounded by water, which is above water at
high tide by reason of human intervention;
(d) the Second Party shall give the First Party three months notice of the proposed grant of exploration or
exploitation rights;
(e) the construction of installations and structures shall be the subject of due notice and a permanent means
of giving warning of their presence must be maintained;
(f) (i) any installation or structure which is abandoned or disused shall be removed by the Party which
authorised its construction in order to ensure the safety of navigation, taking into account any
generally accepted international standards established in this regard by the competent international
organisation;
(ii) such removal shall also have due regard to fishing and to the protection of the marine environment.
Appropriate publicity shall be given to the depth, position and dimensions of any installations or
structures not entirely removed;
(g) the construction of a fish aggregating device shall be the subject of due notice;
(h) the Party constructing an artificial island, installation, structure or fish aggregating device shall have
exclusive jurisdiction over it;
(i) marine scientific research shall be carried out or authorised by a Party in accordance with the 1982
Convention and such research shall be notified to the other Party;
(j) the Parties shall take effective measures as may be necessary to prevent, reduce and control pollution
of the marine environment;
(k) each Party shall be liable in accordance with international law for pollution of the marine environment
caused by activities under its jurisdiction;
(l) any island within the meaning of Article 121.1 of the 1982 Convention which emerges after the entry
into force of this Treaty shall be the subject of consultations between the Parties with a view to
determining its status;
(m) neither Party shall exercise its rights and jurisdiction in a manner which unduly inhibits the exercise of
the rights and jurisdiction of the other Party; and
(n) the Parties shall cooperate with each other in relation to the exercise of their respective rights and
jurisdiction.”
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Illustrative map 1
(reproduced from Department of State of the United States of America, “Limits in the Seas
(No. 141)  Indonesia: Archipelagic and other Maritime Claims and Boundaries”,
September 20144)
30. The agreement on maritime boundaries concluded between Australia and Papua New
Guinea is another example (Treaty between Australia and the Independent State of Papua New
Guinea concerning sovereignty and maritime boundaries in the area between the two countries,
including the area known as Torres Strait, and related matters, concluded 18 December 1978, entered
into force 15 February 1985, UNTS, Vol. 1429, p. 207). Under Article 4 of this Treaty, two maritime
boundaries are established between the two States. The first line is the continental shelf boundary
concerning “seabed jurisdiction”, which is defined as “sovereign rights over the continental shelf in
accordance with international law, and includes jurisdiction over low-tide elevations, and the right
to exercise such jurisdiction in respect of those elevations, in accordance with international law”5.
The second line is the boundary relating to fisheries jurisdiction, defined as “sovereign rights for the
purpose of exploring and exploiting, conserving and managing fisheries resources other than
sedentary species”6. Based on the co-ordinates of the two boundaries, it is shown that, while the two
boundaries in the eastern and western sections coincide, the two boundaries are separate in the middle
section in the area known as the Torres Strait (see illustrative map 2). Papua New Guinea, like
Indonesia, accepted Australia’s position without any reservation. This treaty remains in force to date.
4 Available at https://www.state.gov/wp-content/uploads/2020/02/LIS-141.pdf, p. 12.
5 Article 1 (1) (i) and Article 4 (1).
6 Article 1 (1) (b) and Article 4 (2).
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Illustrative map 2
(reproduced from Department of Foreign Affairs and Trade of Australia, “Guidelines
for Traditional Visitors Travelling under the Torres Strait Treaty”7)
31. Australia reiterated its position on the natural prolongation criterion during the Timor Sea
Conciliation with Timor-Leste on the basis of Article 76, paragraph 1, of UNCLOS in light of the
geological and geomorphological situation of the Timor Trough in the Timor Sea (Timor-Leste v.
Australia, Permanent Court of Arbitration, Case Number 2016-10, Opening Session Transcript,
29 August 2016, p. 91). Although the parties ultimately reached a delimitation agreement
establishing a single maritime boundary for both the exclusive economic zone and the continental
shelf, the Preamble of the Treaty expressly states that “the settlement contained in this Treaty is based
on a mutual accommodation between the Parties without prejudice to their respective legal positions”
(Treaty between the Democratic Republic of Timor-Leste and Australia establishing their maritime
boundaries in the Timor Sea, concluded 6 March 2018, entered into force 30 August 2019, [2019]
Australian Treaty Series 16; emphasis added).
32. A more recent example is the delimitation agreement between Indonesia and the
Philippines concerning the delimitation of the exclusive economic zone in the Celebes Sea concluded
in 2014 (Agreement between the Government of the Republic of Indonesia and the Government of
the Republic of the Philippines concerning the delimitation of the exclusive economic zone
boundary, concluded 2 May 2014, entered into force 1 August 2019, UNTS, Vol. 3324, p. 1). The
distance between the parties in the area in the Celebes Sea is less than 400 nautical miles. In
delimiting the boundary of exclusive economic zones between the two States, the parties took
account of the provisions of UNCLOS and the principles applicable to delimitation. The Agreement
7 Available at https://www.dfat.gov.au/geo/torres-strait/guidelines-for-traditional-visitors-travelling-under-thetorres-
strait-treaty.
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specifically provides that “[t]his Agreement shall not prejudice any rights or positions of the
Contracting Parties with regard to the delimitation of the Continental Shelf boundary”8. Apparently,
the parties to the Agreement do not consider that the boundary of the exclusive economic zone is
decisive for the delimitation of the continental shelf boundary within 200 nautical miles.
33. Similar practice can also be found in other regions. Denmark and the United Kingdom, for
instance, reached an agreement on the maritime delimitation in the area between the Faroe Islands
and the United Kingdom in 1999 (Agreement between the Government of the Kingdom of Denmark
together with the Home Government of the Faroe Islands, on the one hand, and the Government of
the United Kingdom of Great Britain and Northern Ireland, on the other hand, relating to the Maritime
Delimitation in the area between the Faroe Islands and the United Kingdom, concluded 18 May 1999,
entered into force 21 July 1999, United Kingdom Treaty Series (UKTS), 1999, No. 76). Under the
Agreement, the parties delimited the continental shelf in the area and the waters superjacent to the
continental shelf in part of the area and established a special régime, called “the Special Area”, in the
remaining part. The parties made special arrangements for the exercise of fisheries jurisdiction and
rights in the Special Area. In a subsequent protocol concluded in 2012 to the Agreement, the parties
established exclusive economic zones in the waters as previously delimited and decided to retain the
previous boundaries and the Special Area as drawn in the Agreement (UKTS, 2014, No. 22). From
the maritime boundary shown in illustrative map 3 reproduced below, one can see that the Special
Area as a water column is separated from the continental shelf of either party.
Illustrative map 3
(found in Jonathan I. Charney and Robert W. Smith (eds.), International Maritime
Boundaries, 2002, Vol. IV, p. 2955)
8 Article 1, paragraph 3, of the Agreement.
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34. There are other bilateral maritime delimitation agreements, where one party’s extended
continental shelf overlaps with the exclusive economic zone of another party (see Agreement
between the United States of America and the Union of Soviet Socialist Republics on the maritime
boundary, concluded 1 June 1990, applied provisionally since 1 June 1990, Law of the Sea Bulletin,
No. 17, April 1991, p. 15; Treaty between the Kingdom of Norway and the Russian Federation
concerning maritime delimitation and cooperation in the Barents Sea and the Arctic Ocean,
concluded 15 September 2010, entered into force 7 July 2011, Law of the Sea Bulletin, No. 77, 2012,
p. 24)9.
35. In support of its claim, the Respondent refers to Article 2, paragraph 1, of the Treaty
between the Federated States of Micronesia and the Republic of Palau concerning maritime
boundaries and cooperation on related matters, which provides that “no Party shall claim an extended
continental shelf that intrudes into the Exclusive Economic Zone . . . of the other Party” (concluded
16 July 2006, entered into force 16 February 2016, UNTS, Vol. 3210, p. 1). This evidence, contrary
to the position of the Respondent, proves that these two States do not consider that there is a
customary rule that prohibits an extended continental shelf from extending within 200 nautical miles
from the coast of another State, because otherwise such a clause would be unnecessary.
36. Admittedly, States may make special arrangements through bilateral agreements, not
necessarily guided by generally applicable law. Nonetheless, such practice supports the settled
jurisprudence that the régimes of the exclusive economic zone and of the continental shelf, though
interrelated, are distinct and may be delimited separately. Although a single maritime boundary is
generally preferred for the convenience of management, that rationale for the delimitation does not
have a restrictive effect on the entitlement to the extended continental shelf.
C. State practice with regard to CLCS submissions
37. With regard to the submissions of States to the CLCS, the Court notes that the vast majority
of States parties to the Convention that have made submissions to the CLCS have chosen not to assert
therein limits that extend within 200 nautical miles from the baselines of another State. Without any
examination of the submissions of the “vast majority of those States”, the Court considers that “the
practice of States before the CLCS is indicative of opinio juris, even if such practice may have been
motivated in part by considerations other than a sense of legal obligation” (Judgment, para. 77).
Recalling some inconsistent practice of “a small number of States”, the Court takes the view that,
“[t]aken as a whole, the practice of States may be considered sufficiently widespread and uniform
for the purpose of the identification of customary international law”. It further states that, given its
extent over a long period of time, this State practice may be seen as an expression of opinio juris
9 In the Agreement between the United States of America and the Union of Soviet Socialist Republics on the
Maritime Delimitation, the boundary line as determined results in two areas, so-called “special areas”, in which one party’s
exclusive economic zone is superjacent to the continental shelf of the other party. Pursuant to Article 3, each party permits
the other party to exercise “the sovereign rights and jurisdiction derived from exclusive economic zone jurisdiction” that
the other party would otherwise be entitled to exercise under international law. To put it in more simple terms, they transfer
their EEZ rights to each other without changing the maritime title of the respective areas. In the Treaty between the
Kingdom of Norway and the Russian Federation concerning Maritime Delimitation and Cooperation in the Barents Sea
and the Arctic Ocean, the maritime boundary line also produces a “Special Area” which lies within 200 nautical miles of
Norway and beyond 200 nautical miles of the Russian Federation. Article 3 of the Treaty provides that the Russian
Federation shall be entitled to exercise EEZ rights and jurisdiction that Norway would otherwise be entitled to exercise
under international law. It also provides, however, that the Russian Federation’s exercise of such rights and jurisdiction
“derives from the agreement of the parties and does not constitute an extension of its exclusive economic zone” (emphasis
added). Legally speaking, therefore, the Russian Federation’s extended continental shelf is subjacent to the exclusive
economic zone of Norway.
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(Judgment, para. 77). This is a rather loose statement on the practice of States. The Court did not
even bother to address exactly what practice amounts to an expression of opinio juris.
38. First of all, it is necessary to examine the character of the State submissions to the CLCS.
Article 76, paragraph 10, of UNCLOS states that “[t]he provisions of this article are without
prejudice to the question of delimitation of the continental shelf between States with opposite or
adjacent coasts”. Accordingly, the claim that a State has made in its submission to the CLCS may
not be final and binding on its position with regard to the questions of entitlement and delimitation;
a State may leave out a certain portion of its claim in its submission if it deems it necessary, which
does not affect that State’s position in the delimitation. This understanding is supported by the terms
of the CLCS’s mandate and State practice. Pursuant to Rule 46 of the Rules of Procedure of the
CLCS and paragraph 5 (a) of Annex I to the Rules of Procedure, in the case where a land or maritime
dispute exists, the Commission shall not consider and qualify a submission made by any of the States
concerned in the dispute, unless prior consent is given by all the parties to the dispute.
Understandably, in order to have their submissions considered and qualified by the Commission,
States may refrain from extending their continental shelf entitlement within 200 nautical miles from
the coast of other States with a view to avoiding a dispute. Such restraint may be exercised because
of an agreement of the States concerned, a prior unilateral commitment, or a special arrangement.
Some States have made several submissions to the CLCS in respect of their separate territorial areas.
Their claims to an extended continental shelf with respect to those areas do not consistently refrain
from encroaching upon the 200-nautical-mile entitlement of another State. For instance, France’s
submissions in respect of the areas of French Guiana and New Caledonia and in respect of French
Polynesia stop at 200 nautical miles from the coasts of neighbouring States, but its submission
concerning Saint Pierre and Miquelon extends within 200 nautical miles from the coast of Canada.
When Canada raised its objection to the latter submission on the ground that the maritime zones of
Saint Pierre and Miquelon had been definitely settled by arbitration, France maintained that the
arbitral tribunal declared that the question (of an entitlement to a continental shelf beyond
200 nautical miles) did not fall within its competence. It further underscored that “those claims do
not run counter to the United Nations Convention on the Law of the Sea or any rule of international
law” (Note Verbale from the Permanent Mission of France to the United Nations, dated 17 December
2014; emphasis added). Evidently, no consistent State practice can be identified from States’
submissions to the CLCS.
39. When the Court affirms the practice of the “vast majority of States parties” for the
determination of the customary rule, it primarily relies on the 93 submissions from 73 States and the
Cook Islands received by the CLCS so far. According to Colombia, among those 93 submissions,
38 do not reach the 200-nautical-mile limit of another States and, therefore, are irrelevant. Of the
remaining 55 submissions, 51 are said by Colombia to have chosen not to extend the continental
shelf within 200 nautical miles from the coast of other States; in its view, only four States have made
the claim encroaching upon the entitlement within 200 nautical miles of another State10. At first sight,
this looks overwhelmingly persuasive. For the purpose of the present case, however, that practice
obviously needs further scrutiny.
40. Notwithstanding Article 76, paragraph 10, of UNCLOS and the above-mentioned CLCS
rules, studies show that the practice of States is not as certain and consistent as is suggested.
Individually, almost one third of the States that are said to have chosen not to claim their extended
continental shelf within 200 nautical miles of another State have already concluded bilateral
agreements with their neighbouring States on maritime delimitation within 200 nautical miles. That
fact may have a direct bearing on the States’ decision to exercise restraint in their CLCS submissions.
Moreover, as mentioned above, some of the said States have indeed claimed an extended continental
10 These four States include China, the Republic of Korea, Nicaragua and Somalia.
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shelf that extends within 200 nautical miles from the baselines of another State in the delimitation.
In this regard, the most illustrative example is the recent case between Mauritius and the Maldives.
41. In the Mauritius/Maldives case before an ITLOS Special Chamber, the Maldives claims
an extended continental shelf that extends within 200 nautical miles from the baselines of the Chagos
Archipelago (Mauritius). While this is not immediately apparent from the publicly available
Executive Summary of July 2010 of the Maldives’ Submission to the CLCS and the accompanying
maps, the ITLOS Special Chamber noted the existence of such an overlap (Delimitation of the
maritime boundary in the Indian Ocean (Mauritius/Maldives), Preliminary Objections, Judgment of
28 January 2021, para. 332; Delimitation of the maritime boundary in the Indian Ocean
(Mauritius/Maldives), Judgment of 28 April 2023, para. 257). The Maldives itself “confirm[ed] its
position that the Maldives’ entitlement to the continental shelf beyond 200 nautical miles from its
baseline can be . . . extended [within the 200-nautical-mile limit of Mauritius]”
(ITLOS/PV.22/C.28/4, p. 7). Mauritius claimed that the Maldives cannot extend its continental shelf
into the exclusive economic zone of Mauritius, because it had undertaken a specific commitment not
to do so (Delimitation of the maritime boundary in the Indian Ocean (Mauritius/Maldives), Judgment
of 28 April 2023, para. 260). Indeed, Mauritius itself contended that, “if Maldives were entitled to
claim an outer continental shelf within 200 Miles of the baselines of Mauritius, so too could
Mauritius, correspondingly, claim an outer continental shelf that encroaches within 200 Miles of
Maldives” (ITLOS/PV.22/C28/6, p. 29). Ultimately, for reasons concerning the circumstances of that
case, the Special Chamber considered that it was
“not required to address the question whether the Maldives has an entitlement to a
continental shelf beyond 200 nm in the relevant area or the question whether the
Maldives’ entitlement to a continental shelf beyond 200 nm may extend within the
200 nm limit of Mauritius” (Delimitation of the maritime boundary in the Indian Ocean
(Mauritius/Maldives), Judgment of 28 April 2023, para. 275).
The practice of both Mauritius and the Maldives in relation to the latter’s extended continental shelf
reduces the weight of the evidence presented by Colombia. The Maldives’ “restraint” is not based on
a legal obligation derived from a customary rule, nor is Mauritius’s objection to the submission of
the Maldives to the CLCS based on customary international law.
42. Responses to the submissions of the four States that are said by Colombia to have
encroached on the 200-nautical-mile entitlements of other States are also worth noting. In its
communications sent to the United Nations in response to the submissions of China and the Republic
of Korea to the CLCS, Japan, while objecting to the submissions, emphasized the need for
delimitation between the States concerned. With regard to China, Japan states that
“[t]he distance between the opposite coasts of Japan and the People’s Republic of China
in the area with regard to the submission is less than 400 nautical miles[.] The
delimitation of the continental shelf in this area shall be effected by agreement between
the States concerned in accordance with Article 83 of the United Nations Convention
on the Law of the Sea (hereinafter referred to as ‘the Convention’). It is, thus,
indisputable that the People’s Republic of China cannot unilaterally establish the outer
limits of the continental shelf in this area.” (Note Verbale from the Permanent Mission
of Japan to the United Nations, dated 28 December 2012.)
43. Japan made a similar response to the submission by the Republic of Korea. In its reply to
Japan’s objection, the Republic of Korea stated the following:
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“Nothing in the text of the United Nations Convention on the Law of the Sea
(hereinafter referred to as ‘the Convention’) supports the suggestion that the
establishment of the outer limits of the continental shelf beyond 200 nautical miles in
an area where the distance between States with opposite coasts is less than 400 nautical
miles cannot be accomplished under the provisions of the Convention. The Convention
establishes two distinct bases of entitlement in the continental shelf: (1) distance from
the coast; and (2) the geomorphological criteria stated in paragraph 4 of Article 76.
Neither basis is afforded priority over the other under the Convention. Japan, therefore,
cannot use its entitlement based on the distance criterion to negate Korea’s entitlement
based on geomorphological considerations, or to block the Commission from issuing
recommendations with regard to the existence and limits of the continental shelf in the
East China Sea. Accordingly, the Partial Submission of the Government of the Republic
of Korea to the Commission constitutes a legitimate undertaking in conformity with and
in satisfaction of its obligations under the Convention, as well as the relevant provisions
of the Rules of Procedures and the Scientific and Technical Guidelines of the
Commission.” (Note Verbale from the Permanent Mission of the Republic of Korea to
the United Nations, dated 23 January 2013; emphasis added.)
44. In the case of Somalia, Somalia in its 2014 submission claimed that there was an overlap
between Somali and Yemeni claims as regards the areas of the continental shelf beyond 200 nautical
miles and that the delimitation of the continental shelf between the two countries had not yet been
resolved. It indicated that it was ready to enter into consultation with Yemen with a view to reaching
an agreement or understanding which would allow the Commission to consider and make
recommendations on submissions by each of the two coastal States. In its communication to the
Secretary General, Yemen first objected to the consideration by the CLCS of Somalia’s submission
(Note Verbale from the Permanent Mission of the Republic of Yemen to the United Nations, dated
10 December 2014). Somalia amended its submission in 2015, which resulted in an overlap of its
claim with part of Yemen’s entitlements within 200 nautical miles from the coast of Yemen.
Afterwards, Yemen, while reaffirming that there was no agreement or understanding between the
two States regarding the potential overlap of maritime zones beyond 200 nautical miles, indicated
that
“in the interests of advancing the establishments of maritime limits for itself and its
neighbours in the Northwest Indian Ocean, it proposes to remove its objection to the
Article 76 submission by the Federal Government of Somalia, with immediate effect,
provided that a reciprocal obligation was made by Somalia that it no longer has an
objection to the Commission on the Limits of the Continental Shelf examining the
submissions of The Republic of Yemen.” (Note Verbale from the Permanent Mission
of the Republic of Yemen, dated 7 August 2019.)
Apparently, Yemen has left the matter for delimitation.
45. Kenya initially objected to Somalia’s 2014 submission on the ground that a significant part
of Somalia’s continental shelf beyond 200 nautical miles “is appurtenant to an EEZ that is under
Kenya’s jurisdiction”. Subsequently, in withdrawing its objection, Kenya states that,
“as longs [sic] as the Commission is aware of the area of overlapping claims, and that,
in respect of that area, it gives all due consideration to the submissions made by both
States, the Commission may proceed to make recommendations concerning the outer
limits of the continental shelf off the coasts of Somalia and Kenya” (Note Verbale from
the Permanent Mission of the Republic of Kenya to the United Nations, dated 30 June
2015).
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Kenya’s statement to the CLCS apparently did not suggest that Somalia was not entitled to the
continental shelf but asserted that there was an overlap of entitlements.
46. In the western Caribbean region, Colombia, Costa Rica, Jamaica and Panama, individually
or jointly, opposed Nicaragua’s submission on the ground that Nicaragua’s claim encroached upon
their respective maritime areas. They rejected Nicaragua’s assertion that its submission is “without
prejudice to the delimitation of the continental shelf between Colombia, Costa Rica and Panama”
and reaffirmed their respective positions with respect to Nicaragua’s submission (Communication
from the Ministers for Foreign Affairs of Colombia, Costa Rica and Panama, dated 5 February 2014,
referring to the Note Verbale from the Permanent Mission of Nicaragua to the United Nations, dated
20 December 2013). In denying Nicaragua’s claim, these States objected to the Commission’s
consideration and ruling on Nicaragua’s submission. Colombia in its response dated 5 February 2014
referred to the existing maritime boundaries that it had agreed with its neighbouring States, asserting
that the submarine areas in the Caribbean Sea that Nicaragua claimed in its submission belong to
Colombia under international law. As a non-party to UNCLOS, it dismissed the opposability of
Nicaragua’s submission to Colombia. In none of the above communications did these States
explicitly claim that, as a matter of principle, an extended continental shelf may not extend within
200 nautical miles of another State. Colombia’s claim is primarily based on an argument of
established boundaries and the entitlement of its islands.
47. The above discussion shows that, even though many States parties in their submissions to
the CLCS have refrained from claiming a continental shelf that extends within the 200-nautical-mile
maritime zones of another State, they have done so for various reasons; there is no consistent practice
among those States. The subsequent practice of many of them varies from their position in the
submissions, which seriously weakens the evidentiary value of the submissions (Conclusion 7 of the
ILC Conclusions). Moreover, the other constitutive element for the identification of the alleged
rule — opinio juris — must be determined separately (ILC Conclusions, Conclusion 3, comment 7).
There is no evidence shown in the Judgment that those States parties, when restricting their claim in
the submissions, believed that such restraint was required by a legal obligation or guided by law. The
practice of States, particularly those States whose interests are directly or would likely be affected
by such practice, is neither widespread nor consistent. More importantly, no single case can be found
where a State has explicitly given up its entitlement to an extended continental shelf on the ground
that it believes that its continental shelf may not extend within 200 nautical miles of another State
under international law. In any event, the 51 submissions, which the Court considers as reflecting
“the practice of the vast majority of States parties”, in fact, do not truly reflect the positions of the
States parties on the issue in question. As discussed above, States such as Australia, Indonesia, Papua
New Guinea, France, the Maldives, and others, whose submissions are included in the
51 submissions, clearly take a different view on the entitlement to an extended continental shelf that
encroaches on the 200-nautical-mile limit of another State.
48. Taking into account all the available practice of States and assessing it as a whole, it can
be said that there exists neither a general practice nor opinio juris that denies the entitlement of a
State to an extended continental shelf that extends within 200 nautical miles from the coast of another
State. As many States affirm and have done, when such an overlap of entitlements occurs, the matter
shall be settled through the delimitation process in accordance with the rule reflected in Article 83 of
UNCLOS.
49. The potential impact of the present Judgment on the existing State practice, the stability
and security of treaties, the work of the CLCS and States’ submissions is unpredictable, particularly
in respect of the existing treaties and recommendations of the CLCS that have already accepted the
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entitlement to an extended continental shelf that extends within 200 nautical miles of another State.
The CLCS may thus be placed at a crossroads as to what to do with those “problematic” submissions.
III. NICARAGUA’S SUBMISSIONS ON AN EXTENDED CONTINENTAL SHELF
50. Having considered the state of the law, I am of the view that Nicaragua is entitled to an
extended continental shelf, provided the existence and outer limit of its continental margin is proven.
As a precondition for delimitation, Nicaragua has to first prove that its continental margin overlaps
with the entitlements of Colombia. For that purpose, the technical and scientific evidence adduced
by the Parties must first be examined.
51. Procedurally, the expert reports produced by the Parties were not further examined at the
oral proceedings because of the way in which the hearing was organized. From the written pleadings,
technical and scientific evidence produced by Nicaragua seems to prove that its continental shelf, the
Nicaraguan Rise, extends far enough to reach within 200 nautical miles from the mainland coast of
Colombia. At the same time, however, Colombia’s expert reports, in challenging the information
contained in Nicaragua’s submission to the CLCS with regard to the edge of the natural prolongation
of the Nicaraguan land territory in the Caribbean Sea, also seem technically tenable. Without hearing
from the Parties on those reports and without the assistance of experts appointed by the Court, it is
difficult to assess the weight of each piece of evidence. This underscores the value and
indispensability of the recommendations from the CLCS. In hindsight I believe that, in such a
technically complicated case, it is a necessity for the parties to obtain the recommendations of the
CLCS before proceeding to delimitation.
52. Notwithstanding my serious reservations regarding the reasoning of the Court, there are
two major considerations that led me to vote in favour of the Court’s decision.
53. As a technical matter, the Parties are deeply divided over the scientific and technical facts
of Nicaragua’s extended continental shelf. Nicaragua claims that the Nicaraguan landmass extends
eastwards underwater to form the dominant feature in the southwest Caribbean: the Nicaraguan Rise,
which is said to stretch over 500 nautical miles from the Nicaraguan landmass in the southwest to
Jamaica and Haiti in the northeast. The Nicaraguan Rise, as is shown, is separated from the oceanic
abyssal plain of the Colombian Basin to the south by a linear feature: the Hess Escarpment. Its
northern edge is formed by the Cayman Trough, a deep ocean trench lying to the north of Honduras,
running between Guatemala and the north coast of Jamaica, approximately parallel to the Hess
Escarpment. Nicaragua further asserts that the Nicaraguan Rise is divided into two halves: to the
north the Nicaraguan Rise proper and — separated from it by the Pedro Bank Fracture Zone — the
Lower Nicaraguan Rise to the south. The Nicaraguan Rise is about 150 nautical miles wide
(i.e. north-south) and extends from the land territory of Nicaragua in the west to Haiti in the east.
54. Contesting Nicaragua’s claim, Colombia’s expert reports present the analyses of the
scientific evidence collected from public sources and the Colombian Navy on the natural
prolongation of the sea-bed and subsoil from the Nicaraguan land territory into and under the
Caribbean Sea. The key finding of the reports which is relevant to the present case is that the edge
of the natural prolongation of the Nicaraguan land territory in the Caribbean Sea is not the Hess
Escarpment (the southern limit of the Nicaraguan Rise as assumed by the Applicant), but the Pedro
Bank Escarpment-Providencia Trough Lineament, which separates the southern edge of the
Nicaraguan Rise proper from the Lower Nicaraguan Rise. According to Colombia’s experts, the
scope of Nicaragua’s continental margin is much smaller than Nicaragua’s experts suggest and,
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consequently, Nicaragua’s landmass does not extend within 200 nautical miles from the mainland
coast of Colombia.
55. The technical characterization of Nicaragua’s continental margin must be left to scientific
and technical experts. Divergent as they are, the expert reports of the Parties, at the least, inform the
Court of some basic facts that are crucial for the consideration of Nicaragua’s submissions to the
Court for adjudication in the present case.
56. First, the relationship between Nicaragua’s continental margin and Colombia’s mainland
coast remains highly uncertain. Even relying on Nicaragua’s evidence, the outer limit of the Lower
Nicaraguan Rise in the north-east, as defined by Nicaragua, seems overexpansive. The materials
submitted by Nicaragua are not sufficient for the Court to ascertain whether and to what extent
Nicaragua’s continental shelf extends within 200 nautical miles of Colombia.
57. Additionally, the Court has never dealt with such a case where the delimitation involves
the extended continental shelf of only one party. Even assuming that the Nicaraguan Rise is
southbound by the Hess Escarpment, as asserted by Nicaragua, and that Nicaragua’s entitlement is
established and overlaps with Colombia’s entitlements within 200 nautical miles from its mainland
coast, the question nevertheless remains as to what methodology the Court should adopt to delimit
the boundary between the Parties in the area. It seems highly problematic to apply the three-stage
delimitation methodology that is usually used for maritime delimitation within 200 nautical miles;
the relevant considerations for achieving an equitable solution may be quite different in the present
situation.
58. Moreover, the Court should not lose sight of the overall geographical context in which
Nicaragua’s purported continental shelf is located. As is shown on the maps presented by the Parties,
situated on the Nicaraguan Rise, alongside Nicaragua, are Colombia’s Archipelago of San Andrés,
Providencia and Santa Catalina, Jamaica and Haiti. In the western Caribbean, there is Jamaica to the
north and Panama to the south. Notwithstanding the existing delimitation treaties between each of
these States and Colombia, which are not opposable to Nicaragua, res inter alios acta, the
entitlements of those States to a continental shelf within 200 nautical miles would likely overlap with
any extended continental shelf Nicaragua may have. Therefore, it is doubtful that any extended
continental shelf that Nicaragua might have established could be given its full effect to the extent
that Nicaragua claims. As between the Parties, it is Colombia’s islands that are situated in the middle
of the mainland coasts of the two States that prove crucial for the delimitation between the Parties.
59. In the 2012 Judgment, the Court clearly did not delimit the maritime area eastward beyond
the relevant area as identified for the delimitation of the maritime boundary between the Parties
within 200 nautical miles from the mainland coast of Nicaragua (Territorial and Maritime Dispute
(Nicaragua v. Colombia), ICJ Reports 2012 (II), p. 683, para. 159). In rejecting Nicaragua’s
proposal to draw a series of enclaves around each of Colombia’s islands, the Court underscored the
requirement not to produce cut-off effect in the delimitation. It considered, in particular, that
“[e]ven if each island were to be given an enclave of 12 nautical miles, and not
3 nautical miles as suggested by Nicaragua, the effect would be to cut off Colombia
from the substantial areas to the east of the principal islands, where those islands
generate an entitlement to a continental shelf and exclusive economic zone. In addition,
the Nicaraguan proposal would produce a disorderly pattern of several distinct
Colombian enclaves within a maritime space which otherwise pertained to Nicaragua
with unfortunate consequences for the orderly management of maritime resources,
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policing and the public order of the oceans in general, all of which would be better
served by a simpler and more coherent division of the relevant area.” (Territorial and
Maritime Dispute (Nicaragua v. Colombia), ICJ Reports 2012 (II), p. 708, para. 230.)
The Court, by implication, recognized that Colombia’s islands are entitled to their continental shelves
under customary international law. In the present case, should Nicaragua’s second and third
submissions — similar to the request Nicaragua had made in the Territorial and Maritime
Dispute case — be upheld, it would produce a cut-off effect between the islands and the
mainland of Colombia. Indeed, it would not be conducive to an orderly management of the maritime
area and a coherent relationship among the coastal States in the western Caribbean. As Colombia’s
islands in the east face the mainland coast of Colombia, their entitlements to an exclusive economic
zone and continental shelf should be given full effect. Furthermore, they are situated on the landmass
constituting part of the continental shelf claimed by Nicaragua. Under the circumstances, it is
questionable whether Nicaragua could still make a good case for its claim.
60. Based on the foregoing considerations, I come to the conclusion that Nicaragua’s
submissions should not be upheld.
(Signed) XUE Hanqin.
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