Summary of the Judgment of 13 December 1999

Summaries of Judgments, AdvNot an official documents of the Internationa
l Court of Justice

CASE CONClERNINGKAS1KILIjSED:UDUISLAND (BOTSWANA v.NAMIBIA)

Judgment of 1:3December 1999

In its judgment in the case concerning K;~sikili/Sedudu The Court was con~posed as follows: President
Island (BotswanaINamibia), the Court found, by eleven Schwebel; Vice-President Weeramantry; Judges Oda,
votes to four, that "the boundary betweenth: Republic of Bedjaoui,Guillaume,Ranjeva,Herczegh,Shi, Fleischhauer,
Botswana and the Republic of Namibia follows the line of Koroma, Vereshchetin, Higgins, Parra-Aranguren,
the deepest soundings in the northern channel of the ChobeKooijmans,Rezek;RegistrarValencia-Ospina.
River around KasikililSedlnduIsland" and, by eleven votes
*
to four again, thatasikili/SeduduIsland forms part ofthe * *
territory ofthe RepublicOBotswana".
The Court added unanimously that,"in the two channels The full text of theoperativeparagraph of the Judgment
around KasikiliISeduduIsland, the nationals of. and vessels
flyi.ng the flags of, the Republic of Botswana and the readsas follows:
Republicof Namibia shall enjoyequalnationaltreatmenty'. "104. For these reasons.

Continued on nepage THE COURT, Botswana's final submission as presented at the hearing

(1) By elevenvotesto four, of 5 March 1999wereas follows:
Fiitds that the boundary between the Republic of "Mnvitplease the Court:
Botswana and theRepublic of Namibia follows the line (1) to adjudgeand declare:
of deepest soundings in the northern channel of the
ChobeRiveraround KasikiliISeduduIsland; (a) that the northern and western channel of the
Chobe River in the vicinity of KasikiliISedudu Island
IN FAVOUR: President Schwebel; Judges Oda, constitutes the 'main channel' of the Chobe Riverin
Bedjaoui, Guillaume,,Ranjeva, Herczegh, Shi,Koroma, accordance with the provisions of ArticleI11(2) of the
Vereshchetin,Higgins,Kooijmans; Anglo-GermanAgreementof 1890;and
AGAINST: Vice-President Weerainantry; Judges (b) consequently, sovereigntyin respect of Kasikilil
Fleischhauer,Parra-Aranguren,Rezek.
Sedodu Island vests exclusively in the Republic of
(2) By elevenvotes to four, Botswana;and further
Finds that KasikiliISeduduIsland forms part of the (2) to determine the boundary around Kasikilil
territoryoftheRepublicof Botswana; SeduduIsland onthebasis of the thalwegin the northern
andwesternchanneloftheChobeRiver."
IN FAVOUR: President Schwebel; Judges Oda,
Bedjaoui, Guillaume, Ranjeva, Herczegh, Shi, Koroma, Namibia's final submissions read at the hearing of 2
Vereshchetin,Higgins.Kooijmans; March 1999were as follows:
AGAINST: Vice-President Weeramantry; Judges "Mqv it please the Court, rejecting all claims and
Fleiscl~l~auer,arra-Aranguren,Rezek. submis.sioitsto thecontrary, to anjlrdgeand declare

(3)Unanimously, I. The channel that lies to the south of
Finds that, in the two channels around KasikililSeduduIsland is themain channelof the Chobe
KasikiliISedudu Island, the nationals of, and vessels River.
flying the flags of, the Republic of Botswanaand the 2. The channel that lies to the north of
Republic of Namibia shall enjoy equal national KasikiliISedudu Island is not the main channel of the
ChobeRiver.
treatment."
3. Namibia andits predecessorshave occupied and
used.Kasikili Islandand exercised sovereignjurisdiction
over it, with the knowledge and acquiescence of
Botswanaand its predecessorssinceat least 1890.
Judges Ranjeva, Koroma, and Higgins appended 4. The boundary between Namibia and Botswana
declarations to the judgment of the Court; Judges Oda and
Kooijmans appended separate opinions;and Vice-President around KasikiliISeduduIsland liesin the centre (that is
Weeramantryandjudges Fleichhauer, Parra-Aranguren and to say, the thalweg)of the southernchannelof the Chobe
Rezek appendeddissentingopinions. River.
5. The legal status of KasikiliISeduduIsland isthat
it is a part of the territory under the sovereignty of
Namibia."

Review of theproceediilgs and szlbinissioilsofthe Backgivuitd to the case
Parties (paras. 11-16)
(paras. 1-10)
The Court then gives a description of the geography of
By joint letter dated 17 May 1996, Botswana and the areaconcerned,illustratedby three sketchmaps.
Namibia transmitted to the Registrar the originaltext of a Thereafter the Court recounts the history of the dispute
Special Agreement between the two States, signed at between the Parties which is set against the background of
Gaborone on 15February 1996andentered into forceon 15
the nineteenth century race among the European colonial
May 1996,Article I ofwhich readsas follows: powers for the partition of Africa. In the spring of 1890,
"The Court is asked to determine,on thebasis of the Germanyand Great Britain enteredinto negotiationswith a
Anglo-German Treaty of 1 July 1890 [an agreement view to reaching agreement concerning their trade and their
between Great Britain and Germany respecting the spheresof influencein Africa.The resultingTreatyof 1July
spheres of influence of thetwo countries in Africa] and 1980 delimited inter alia the spheres of influence of
the rules and principles of international law, the Germany and Great Britain in south-west Africa; that

boundary between Namibia and Botswana around delimitationlies at the heart of the present case.
KasikiliISedudu Island and the legal status of the In the ensuing century, the territories involved
island." experiericedvarious mutations in status. The independent
The Court then recites the successive stages of the Republic of Botswana came into being on 30 September
proceedingsand setsoutthe submissionsof the Parties: 1966, on the territory of the former British BechuanalandProtectorate, while Naniibia (of which the Caprivi Strip The text of the 1890 Peaty
forms part) became independenton 21 March 1990. (paras. 21-46)

Shortly after Namibian independence, differences arose: The Court first examines the text of the 1890 Treaty,
between the two State:; concerning the location of the: Article111of whichreads as follows:
boundary around KasikiliISedudu Island. In May 1992, ii: "In Southwest Africa the sphere in which the
was agreed to submit the determination 01 the boundary
around the Island to a Joint Team of Technical Experts. In exerciseof influenceis reservedto Gennany is bounded:
February 1995, the Joint Team Report, in which the Team 1. To the south by a line commencing at the mouth
announced that it had failed to reach an agreed coi~clusior~ of the Orangeriver. and ascendingthe north bankof that
river to the point of its intersectionby the 20th degree of
on the question put to it, was consideredand it was decided east longitude.
to submit the dispute to the InternationalCourt of Justicefor
a final andbinding determination. 2. To the east by a line commencing at the above-
named point, and following the 20th degree of east
The i.zr1esof iiztei-pi-etatioilapplicable to the 1890 Ti.eatj9 longitude to the point of its intersection by the 22nd
(piiras. 18-20) parallel of south latitude: it runs eastward along that
parallel to the point of its intersectionby the 21st degree
The Court begins by observingthat the lawapplicableto of east longitude; thence it follows that degree
the present case has its source first in the 1890 Treaty., northward to the point of its intersection by the 18th
which Botswana aiid Namibia acknowledge to be binding;
parallel of south latitude; it runs eastward along that
on them. As regards the interpretation of that Treaty, the parallel till it reaches the river Chobe, and descends the
Ca,urtnotes that neither Botswana norNamib:iaareparties tcl centre of the main channel of that river to its junction
tlie Vienna Convention on the Law of Treaties of 23 May with theZambesi,where it terminates.
19,69,but tliat both of thein consider that Article 31 of the: It is understood that underthis arrangementGermany
Vi,enna Convention is applicable inasiiiuch as it reflects. shall have fiee access from lier Protectorate to the
cu:itomaryinternationallaw.
Zambesiby a strip of territorywhich shallat no point be
Accordingto Article 31of the ViennaConventionon the lessthan 20 Englishtniles in width.
Law of Treaties: The sphere in which the exercise of influence is
"1. A treaty shall be interpreted in good faith in. reserved to Great Britain is bounded to the west and
accordancewith the ordinary meaningto be given to the northwest by the above-mentionedline. It includesLake
terms of the treaty intheir context and in the light of its Ngami.
object and purpose.
The course of the above boundary is traced in
2. The context fcr the purpose of thf:interpretation general accordance with a map officially prepared for
of a treaty shall comprise, in addition to the text, the BritishGovernmentin 1889."
includingits preambleand annexes: As far as the region covered by the present case is
(a) any agreement relating to tlie treaty which was
concerned, this provision locates the dividing line between
made between all the parties in connection with the the spheres of influence of the contracting parties in the
conclusionof the treaty; "tnain channel" of the River Chobe: however, neither this,
(b) any instrument which was made by one or more nor any otlier provision of the Treaty, furnishes criteria
parties in connection with the conc1usio:nof the treaty enabling that "main channel" to be identified. It must also
and accepted by the otlier parties as an instrument be noted that inthe English vcrsion refers to the "centre" of
relatedto the treaty." the main channel?while the German version uses the tern]
"thalweg" of that channel (Thal~vegdes Halptlarfes).
The Court indicates that it shall proceed to interpret the
provisions of tlie 1890 Treaty by applying the rules of Observing that Botswana andNamibia did not themselves
interpretation set forth in the 1969 Vienna Convention, express any real difference of opinion on the meaning of
rec:allingtliat these terms, the Court indicatesthat it will accordinglytreat
"a treatymust be interpretedin good faith, in accordance the words "centre of the main channel" in Article 111,
paragraph2, of the 1890Treatyas having the satnemeaning
with the ordinary meaning to be given to its terms in as the words "Thalweg des Hauptlaufes". In the Court's
their contextaiid in the light of its object and purpose. opinion, the real dispute between the Parties concerns the
Interpretationmust bl: based above all upon the text of
the treaty. As a supp11:mentarymeasure recoursemay be location of the tnain channel where the boundary lies. In
had to tneans of interpretation such as the preparatory Botswana's view, it is to be found "on the basis of the
work of the treaty." (Territorial Dispute (Libj~unArab thalwegs inthe northernand western channelof the Chobe",
Jai~~nhiriyc~/CItad~ J, dgment, I.C.J. Ileports 1994, whereas in Namibia's view, it "lies in the centre (that is to
say thalwegs) of the southern channel of the Chobe River".
pp. 21-22,para. 41). The Court observes that by introducing the term "main
channel" intothe draft treaty,the contractingparties mustbe

assumedto have intended thata precisemeaningbe givento
it. Forthese reasons,the Court indicatesthat it will thereforeproceed first to determinethe tnain channel.In so doing, it Width
will seek to determine the ordinary meaning of the words (para. 33)
"main channel" by reference to the most commonly used
criteria in iiltei~latioilallaw and practice, to which the With regardto the width, the Court finds,on the basis of
Parties have referred. a report dating from as early as 1912, aerial photographs
taken between 1925and 1985,and satellitepicturestaken in
June 1975, that the northern channel is wider than the
Ci.itei,ia.for ideiitifiing the "mainchannel" southernchannel.
(paras. 29-42)

The Court notes that the Parties to the dispute agreeon Flow of water
many of the criteria for identifying the"main channel", but (paras. 34-37)
disagree on the relevance and applicability of several of
those criteria. With regard to the flow, i.e., the volume of water
carried,the Courtis not in a positionto reconcilethe figures
For Botswana, the relevant criteria are as follows: submitted by the Parties, who take a totally different
greatest depth and width; bed profile configuration; approach to the definition of the channels concerned. The
navigability; greater flow of water. Botswana also lays Court is of the opinion that the determination of the main
stress on the importance, from the standpoint of channel must be made according to the low water baseline
identification of the main channel, of "channel capacity",
"flow velocity" and "volume of flow". Namibia and not the floodline. The evidence shows that when the
acknowledgesthat: river is In flood, theIsland is submergedby floodwater and
the entire region takes on the appearance of an enormous
"[p]ossible criteria for identifying themain channel in a lake. Slince the two channels are then no longer
river with more than one channel are the channel with distinguishable, it is not possible to determine the main
the greatest width, or the greatest depth, or the channel channelin relation to the other channel. The Court therefore
that carries the largest proportionof the annual flow of
the river. In many cases the main channel will have all is not persuaded by Namibia's argument concerning the
existenceof a major "main" channel whosevisible southern
threeof these characteristics." channel wouldmerely constitutethe thalweg.
It adds, however, referringto the sharp variationsin the
level of theChobe's waters, that: Ksibility
"neither width nor depth are suitable criteria for (para. 38)

deteiminingwhich channel isthe main channel." The Court is further unableto conclude that, in terms of
Among the possible criteria, Namibia therefore attaches visibility- or of general physical appearance - the
the greatest weight to the amount offlow: according to it,
the main channel is the one "that carries the largest southeni channel is to be preferred to the northern channel,
proportion of the annual flow of the river". Namibia also asmainfiainedby Namibia.

emphasizedthatanotherkeytask wasto identifythe channel Bedprofile configuration
that is most usedforrivertraffic. (para. 39)
The Court notes that the Parties have expressed their
views on one or anotheraspect of the criteria, distinguishing Having examined the arguments, maps and photographs
betweenthem or placing emphasison their complementarity put forward by the Parties, the Court is also unable to
and their relationshipwith other criteria. Before coming to a conclude that, from its bed configuration, the southern

conclusion on the respective role and significance of the channel constitutesthe principaland natural prolongation of
various criteriathus chosen, the Court further notesthat the the courseof the Chobebefore thebifurcation.
present hydrological situation of the Chobe around
KasikiliISeduduIsland may be presumed to be essentially Navigability
the same as that which existed when the 1890Treaty was (paras. 40-42)
concluded.
The Court notes that the navigability of watercourses
varies g~eatly,depending on prevailing natural conditions.
Depth Those conditions can prevent the use ofthe watercourse in
(para. 32)
questior~by large vessels canying substantial cargoes, but
Notwithstandingall the difficultiesinvolvedin sounding permit light flat-bottomedvessels to navigate. In thepresent
the depth of the channels and interpreting the results, the case, the data furnishedby the Parties tend to prove that the
Court concludesthat the northern channel is deeperthan the navigability of the two channels around KasikiliISedudu
souther11one, as regards mean depth, and even as regards Island is limitedby their shallowness.This situationinclines
minimumdepth. the Coilrt to the view that, in this respect, the "main

channel"' inthis part of the Chobe is thatof the two which
offers more favourable conditions for navigation. In the
Court's view,it is the northern channel which meets this
criterion. For the foregoing reasons, the Courtconcludl:~that, in In supportofits interpretationof Article111, aragraph2,
accordance with the ordinary meaning of the terms that #ofthe 1890Treaty,Botswanarelies principallyon three sets
appear in the pertinent provision of the 1890 Treaty, the 'ofdocuments: a report on a reconnaissance of the Chobe
northern channel of the River Chobe around -producedin August 1912by anofficer of the Bechuanaland

KasikiliISedudu Island must be regarded as its main ProtectoratePolice, Captain Eason; an arrangementarrived
chanllel.It observesthat this conclusion is supportedby the .atin August 1951 between MajorTrollope, Magistrate for
resultsofthree on-sitesurveyscarriedout in 1912..1948and -the Eastern Caprivi, and Mr. Dickinson, a District
1985, which concluded that the mainchannel of the River ,Commissionerin the Bechuanaland Protectorate, together
Chobe was the northern channel. with the correspondence that preceded and followed that
.arrangement;and an agreement concluded in December
1984between the authorities of Botswanaand South Africa
The object and pzlrpose oj'the 1890 Treaty
(paras. 43-46) for the conduct of a Joint Survey of the Chobe. together
withthe resultantSurveyReport.
Thc Court then considers how and to what extent the
object and purpose of the treaty can clarify the meaning to TheEnsoil Report (1912)
be given to its terms. While.thetreaty in question is not a (paras. 53-55)
boundary treaty proper but a.treaty delimiting ripheresof
influence, the Parties nonetheless accept it as the treaty The Court shares the view,put forwardby Namibia and
determining the boundary between their territories. The acceptedby Botswana in the finalversion of its argument,
that the Eason Report and its sui~oundingcircumstailces
contracting powers, the Court observes,by opting for the
words "centre of the main channel", intendedto establish a cannot be regarded as representing"subsequent practice in
boundary separating their spheres of influence even in the theapplicationof thetreaty" of 1890, within themeaningof
case of ariverhavingmore thanone channel. Article31,paragraph3 (b), ofthe ViennaConvention.
The Court notes that navigation appearsto have been a
factor in the choice of the co~ntractipowers in delimiting The Trollope-Redinan correspondence (1947-1951)

their spheres of influence, but it does not consider that (paras. 56-63)
navigation was the sole objective of the provisions of In 1947, Mr. Ker, who was operating a transport
Article 111,paragraph 2, of the Treaty. In referring to the
inain channelofthe Chobe,the parties soughtbothto secure businessin Bechuanaland,plannedto bring tiliiberdown the
for themselves freedoin of navigation on the river and to Chobe using the northern channel. He obtained the
delimit as precisely as possible their respective spheres of necessary permission froin the competent official in the
influence. Caprivi Strip, Major Trollope, but also raised the matter
withthe Bechuanalandauthorities.Following a JointReport
entitled "Boundary between the Bechuanaland Protectorate
Thesl4iiseq1ientpractice andtheEastern CapriviZipfel:KasikiliIsland"producedby
(paras. 47-80)
Major Trollopeand Mr. Redmail(District Comlnissioiierat
In the course of theprocee:dings,Botswanaand Namibia Kasane, Bechuanaland) in 1948, and forwarded to their
made abundant reference to the subsequent practice of the respective authorities, there ensued an extended
parties to the 1890 Treaty- and of their successors- as correspondencebetween thoseauthorities.
an element in the interpretation of that Treaty. VJhileboth In 1951 an exchange of correspondence between Mr.
Parties acceptthat interpretativeagreementsand subsequent Dickinson, who had in the meantime succeeded Mr.

practice do constituteelementsof treaty interpretationunder Redman as District Commissioner at Kasane
international law, theydisagree on the consequencesto be (Bechuanaland) and Major Trollope led to the following
drawn from the facts in this case for purposes of the "gentlemen'sagreement":
interpretationofthe 1890Treaty. "(a) That we agree to differ on the legal aspect
Article 31, paragraph3, o-the 1969Vienna Convention regarding Kasikili Island, and the concoinitant question

on the Law of Treaties, which, as stated earlier, reflects of theNorthernWaterway;
custom.arylaw, provides,forthe interpretationof aeaties, as (b) That the administrative arrailgementswhich we
follows: hereafter make are entirely without prejudice to the
"'3.There shall be taken into account, together with rights of the Protectorate and the Strip to pursue the
the context: legal question mentioned in (a) should it at any time
seem desirable to do so and will not be used as an
((a)any subsequent agreement between the parties
regarding the interpretation of the treaty or the argument that either territory has made any admissions
applicationofitsprovisiofi~s; or abandoned anyclaims;and
~(b)ny subsequentpra.cticein the application of the (c) That, havingregardto the foregoing,the position
treaty which establishes the agreement of the parties revert to what it was de facto before the whole question
was made an issue in 1947 - i.e. that Kasikili Island
regarding itsinterpretations."
continue to be used by Caprivi tribesmen and that the Nortliern Waterway continue to be used as a 'free for Air photographs showingtlie channels of the river in
all' thoroughfare." the vicinity of the island are available in the archives of
Each side however made a caveat with regard to its the two national survey organizations. They were taken
position in anyfuturecontroversyoverthe Island. in 1925, 1943. 1972, 1977, 1981 and 1982. No
substzntial change in the position of the channels is
The Court observesthat each of the Parties to the present evidentfrotnthe photographs."
proceedingsrelies on the Trollope-RedmanJoint Report and
the correspondence relating thereto in support of its Having examined the subsequent correspondence
position. Froni its examination of the extended between tlie South African and Botswana authorities, the
correspondencc, the Court concludes that the above- Court finds that it cannot conclude therefrom that in 1984-
mentioned events, which occurred between 1947and 1951, 1985 South Africa and Botswana had agreed on anything
more than the despatch of the joint team of experts. In
demonstratethe absence of agreementbetween SouthAfrica particular, the Court cannot conclude tliat the two States
and Bechuanaland with regard to the location of the
boundary around KasikiliISedudu Island and the status of agreed in some fashion or other to recognize themselves as
the Island. Those events cannot therefore constitute legallybound by the results of thejoint surveycarried out in
"subsequenit practice in the applicatioii of the treaty [of Jul:y1985.Neither the record of the meetingheld inPretoria
18901 which establishes the agreement of the parties on 19 December 1984 nor the experts' terms of reference
regarding its interpretation" (1969 Vienna Convention on serve to establish that any such agreement was reached.
Moreover, the subsequent correspondence between the
the Law of Treaties, Art. 31, para. 3 (h)). A,for-tiori,they
cannot have given rise to an "agreementbetween the parties South African and Botswana authorities appears to deny the
regarding tlie interpretation of the treaty 01.the application existence of any such agreement: in a Note of 4 November
of its provisions" (ibid.,Art. 31,para. 31)). 1985, Botswana called upon South Africa to accept the
survey conclusions; not only did SouthAfrica fail to accept
them but on several occasions it emphasized the need for
TheJoint Sz4rveyof 1985 Botswana to negotiate and agree on the question of the
(paras. 64-68) boundary with the relevant authorities of South West
In October 1984 an incident during which shots were
Africa/Namibia, or indeed of the future independent
fired took placebctweenmembers of the BotswanaDefence Namibia.
Force and South African soldiers who were travelling by
boat in the Chobe's southern channel. At a meetingheld in Presence of Masc~hiaon the Iiland
Pretoria on 19 December 1984 between representatives of (paras. 71-75)
various SouthAfrican and Botswananministries,it emerged
that the incident had arisen out of differences of In the proceedings Namibia, too, invoked in support of
interpretation as to the precise location of the boundary its arguments the subseque~itpractice of the parties to the
1890Treaty. In its Memorialit contendedthatthis conduct
around KasikiliISedudu Island. At this meeting, reference
was made to the terms of the 1890Treaty and it was agreed "is relevant to the present controversy in three distinct
"tliat ajoint survey shouldtake place as a matter of urgency ways. In the first place, it corroboratesthe interpretation
to determine whether the main Channel of the Chobe River of the Treaty ...Second, it gives rise to a second and
is located to the north or the south of the SidudufKasikili entirely independentbasis forNamibia's claimunder the
Island". Thejoint surveywas carried out at the beginningof doctrines concerning acquisition of territory by

July 1985. The conclusions of the survey report were as prescription, acquiescence and recognition. Finally, the
follows: conduct of the parties shows that Namibia was in
"The iliain channel of the Chobe River now passes possession of the Island at tlie time of termination of
SiduduIKasikiliIsland to the west and to the north of it. colonial rule, a fact that is pertinent to the application of
(See annexedmaps) theprinciple oflrtipossidetis."
The subsequent practice relied on by Namibia consists
The evidenceavailable seems to point to the fact that
this has been the case,at least,since 1912. of
It was not possibleto ascertainwhether a particularly "[tlhe control and use of Kasikili Island by the Masubia
heavy flood changed the course of the river between of Caprivi,the exerciseofjurisdiction over the Islandby
1890 and 1912. Captain Eason of the Bechuanaland the Namibian governing authorities, and the silence by
Botswana and its predecessors persisting for almost a
Protectorate Police states, on page 4 of Part 1 of the
report which has been referred to earlier, that floods centurywith fullknowledgeof the facts ..."
occurredin 1899and inJune and July of 1909. The Court indicatesthat it will not at this point examine
If the main channel of the river was ever situated to Namibia's argument concerningprescription.It will merely
the south of the island, it is probable that erosion in the seek to ascertain whether the long-standing, unopposed,
presence of Masubiatribespeople on KasikiliISeduduIsland
Sidudu Valley, the location of which can be seen in the
annexed Map C, has caused the partial silting up of the constitutes "subsequent practice in the application of the
southernchannel. [I8901treaty which establishes the agreement of the parties
regarding its interpretation" (1969 Vienna Convention onthe Law of Treaties, Art. 31, para. 3 (b)). To establishsuch channel.Rather,its overallpositionis that the mapevidence
practice, at least two criteria would have to be satisfied: is far less consistentin placingthe boundaryin the southern
first, that the occupation of the Island by the Miisubiawas channelthan Namibiaclaims.
linked to a belief on the part of the Caprivi authorities that The Courtbeginsby recallingwhat theChamberdealing
the boundary laid down by the 1890Treaty followed the
with theFrontier Dispute (BurkinuFaso/Republic of Mali)
southern channel of the Chobe; and, second, that the casehad tosayonthe evideiltiaryvalue of maps:
Bechuanaland authoritiesweirehlly aware of and accepted "maps merely constitute information which varies in
this as a confirmationof the Treatyboundary. accuracyfrom case to case; of themselves,and by virtue
There is nothingthat shows, in the opinionof'theCourt, solely of their existence, they cannot constitute a
that the intermittent presence on the Island of people from
territorial title, that is, a documeilt endowed by
the Ca.priviStrip was linked to territorial c1ai:as by the international law with intrinsic legal force for the
Caprivi authorities.It further seems to the Court that,as far purpose of establishing territorial rights. Of course, in
as Bechuanaland, and subsequently Botswana, were some cases maps may acquire such legal force, but
concerned, the intermittent presenceof the Mast~biaon the where this isso the legal forcedoesnot arise solelyfrom
Island did not trouble any0n.eand was tolerated, not least their intrinsicmerits: it is becausesuch mapsfall into the
because itdid notappearto beconnectedwith interpretation category of physical expressions of thewill of the State
of the ternls of the 1890 Treaty. The Court thus finds that
or Statesconcerned.This is the case, for example,when
the peaceful and public use of KasikiliISeduduIsland, over maps are annexedto an official text of which theyfonn
a period of many years, by Masubia tribesmen from the an integralpart. Exceptinthis clearlydefinedcase,maps
Eastern Caprivi does not con~stitut"subsequent practice in are only extrinsic evidence of varying reliability or
the application of the [I8901 treaty" within the meaning of unreliability which may be used, along with other
Article 31.paragraph3 (b).oEthe Vienna Conventiononthe evidence of a circumstantial kind, to establish or
Lawof Treaties. reconstitutethe real facts."I.C.J. Reports 1986,p. 582,

para. 54)
After examiningthe mapevidenceproduced inthis case,
The Court concludes from all of the foregoiilgthat the the Court considers itself unable to draw conclusions from
subsequentpracticeof the parties to the 1890Treaty did not it, in viewof the absenceofany mapofficiallyreflectingthe
result in any "agreement between the parties regarding the intentions of the parties to the 1890 Treaty and of any

interpr,etation of the treaty or the application of its expressor tacit agreementbetween themor their successors
provisions", within the meaning of Article 31, paragraph concerning the validity of theboundary depicted in a map,
3 (a), of the 1969 Vienna Convention on the Law of aswell asinthe lightofthe uncertaintyandinconsistencyof
Treaties,nor did it result in any "practice in the :applicationthe cartographic material submitted to it. That evidence
of the treaty which establishes the agreementof the parties cannot therefore "endors[e] a conclusion at which a court
regarding its interpretation", within the meaning of has arrived by other means unconnected with the maps"
(Frontier Dispute (Bzlrkii~aFaso/Republic of Mali), I.C.J.
subparagraph (b)of that same:provision.
Reports 1986,p. 583.para. 56),nor can it alterthe results of
Maps ,asevidence the Court's textual interpretationof the1890Treaty.
(paras. 81-87)
"Ceiltre of the muin channel" or Tl1alweg
Both Parties have submitted in evidence in support of (paras. 88-89)
their respective positions a large number of maps, dating
back as far as 1880.Namibia.points out thatthe inajorityof The foregoinginterpretationoftherelevantprovisionsof
the maps submitted in these proceedings, even those the 1890 Treaty leads the Court to conclude that the
emanating from British colonial sources and intended to boundary between Botswana and Namibia around

show the boundaries of Bechuanaland, tend to place the KasikiliISeduduIslandprovided for in this Treaty lies in the
boundary around KasikiliISedudu Island in the southern northernchannelof the ChobeRiver.
channel. Namibia relies on this as "a specialized form of According to the English text of the Treaty, this
'subsequent practice' and ...also an aspect both of the boundary follows the "centre" of the main channel; the
exercise of jurisdiction ancl the acquiescence in it that German text uses the word "thalweg". The Court has
matures into prescriptivetitle". Botswanafor its part places alreadyindicatedthatthepartiesto the 1890Treatyintended

less reliance on maps, pointing out, inter alia, thatmost of these terms to be synonymous and that Botswana and
the early maps show too little detail, or are too small in Namibia had not themselves expressed any real difference
scale,to be ofvalue in this case. Botswanaassert:;,however, of opinionon this subject.
that the availablemaps and sketches indicate that, from the It is moreover clear from the travnzixpr&paratoires of
time the Chobe was surveyed with any particularity by the Treatythat therewas an expectationofnavigationon the
European explorers from .the 1860s onwards, a north
channel around the Island was known and regularly Chobe by both contractingparties, and a common intention
to exploit this possibility.Although the partiesin 1890used
depicted. Botswana does not, however, a.ttempt to the terms "thalweg" and "centre of the channel"
demonstrate that this places the boundary in the northerninterchangeably, the former reflects more accurately the The Court continues by pointing out that for present
common intention to exploit navigation than does the latter. purposes, it need not concern itself with the status of

Accordingly this is the term that the Court will consider acquisitive prescription in international law or with the
determinative inArticle 111,paragraph 2. conditionsfor acquiringtitle to territory by prescription.The
Inasnluch as Botswana and Namibia agreed, in their Court considers, for the reasons set out below, that the
replies to a question put by a Member of the Court, that the conditions cited by Namibia itself are not satisfied in this
thalweg of the Chobe was formed by the line of deepest case and that Namibia's argument on acquisitive
prescriptionthereforecannot be accepted.
soundings in that river, the Court concludes that the
boundary follows that line in the northern channel around The Court observes that it follows froin its examination
KasikiliISedudu Island. ofthe presence of the Masubiaon the Island (see above) that
even if links of allegiance may have existed between the
Acquisitive prescription Masubia and the Caprivi authorities, it has not been
established that the members of this tribe occupied the
(paras. 90-99) Island cititre de so14ver.aiii.,e., that they were exercising
The Court continues by observing that Namibia,
however, claims title to KasikiliISedudu Island, not only on func1:ions of State authority there on behalf of those
authorities. Indeed, the evidence shows that the Masubia
the basis of the 1890 Treaty but also, in the alternative, on used the Island internlittently, according to the seasons and
the basis of the doctrineofprescription. Namibia argues that their needs, for exclusively agricultural purposes; this use,
"by virtue of continuous and exclusive occupation and which began prior to the establishment of any colonial
use of Kasikili Island and exercise of sovereign administration in the Caprivi Strip, seems to have
jurisdiction over it from the beginning of the century, subsequently continued without being linked to territorial

with full knowledge, acceptance and acquiescence by claims on the part of the Authority administering the
the governing authorities in Bechuanaland and Caprivi. Admittedly, when, in 1947-1948, the question of
Botswana,Namibia hasprescriptivetitle to the Island". the boundary in the region arose for the first time between
Botswana maintains that the Court cannot take into the local authorities of Bechuanaland Protectorate and of
consideration Namibia's arguments relating to prescription SouthAfrica,the Chobe's "main channel" aroundthe Island
and acquiescence as these are not ii~cludedin the scope of was said to be the northern channel, but the South African
authorities relied on the presence of the Masubia on the
the question submitted to it under the terms of the Special
Agreement. Island in order to maintain that they had title based on
The Court notes that under the terms of Article I of the prescription. However, from then on the Bechuanaland
Special Agreement it is asked to determine the boundary authorities took the position that the boundary was located
between Namibia and Botswana around KasikiliISedudu in the northern channel and that the Island was part of the
Protectorate; after some hesitation, they declined to satisfy
Island and the legal status of the Island "on the basis of the South Africa's claims to the Island, while at the same time
Anglo-German Treaty of 1 July 1890 and the rules and
priilciples of international law". In the Court's view the recognizing the need to protect the interests of the Caprivi
Special Agreement, in referring to the "rules and principles tribe!;. The Court infers from this, first, that for
of international law", not only authorizes the Court to Bechuanaland, the activities of the Masubia on the Island
interpret the 1890 Treaty in the light of those rules and were an independent issue from that of title to the Island
principles but also to apply those rules and principles and, second, that, as soon as South Africa officiallyclaimed
title, Bechuanaland did not accept that claim, which
independently. The Court therefore considers that the precludedacquiescence on its part.
Special Agreement does not preclude the Court from
examiningargumentsrelating to prescriptionput forward by In the Court's view, Namibia has not established with
Namibia. the necessary degree of precision and certainty that acts of
After summarizing the arguments advanced by each of State authority capable of providing alternativejustification
for prescriptive title, in accordance with the conditions set
the Parties the Court observes that they agree between out by Namibia, were carried out by its predecessors or by
then~selves that acquisitive prescription is recognized in
international law and that they hrther agree on the itself with regard to KasikiliISeduduIsland.
conditions under which title to territory may be acquired by
prescription, but that their views differ on whether those The Iegal statcls of the Island and the two channels
conditions are satisfied in this case. Their disagreement arocrndit
relates primarilyto the legal inferences which may bedrawn (paras. 100-103)

froin the presence on KasikiliISeduduIsland of the Masubia The Court's interpretation of Article I11(2) of the 1890
of Eastern Caprivi: while Namibia bases its argument Treaty has led it to conclude that the boundary between
primarily on that presence, considered in the light of the Botswana and Namibia around KasikiliISedudu Island
concept of "indirect rule", to claim that its predecessors
exercised title-generating State authority over the Island, follows the line of deepest soundings in the northern
Botswana sees this as simply a "private" activity, without channel of the Chobe. Since the Court has not accepted
anyrelevance in the eyesof internationallaw. Namibia's argument on prescription, it follows thatKasikiliISedudu Island forms part of the territory of functions of State authority there on behalf of those
Botswana. authorities"
The Court observes: however, that the Kasane is not of general import and relates only to the particular

Com~muniquC of 24 May 1992records that the Presidentsof circumstancesof the presentcase.
Namibia andBotswanaagreedand resolved that:
"(c) existing social interactionbetween the people of Declaration of Judge Koroiizu
PJamibiaand Botswanashouldcontinue;
In his declaration Judge Koroma stated that the
(4 the econonlic activities such as fishing shall Governments of Namibia and Botswana should be
continue on tlie understanding that fishing;nets should commended for their decision to bring their dispute to the
a~otbe laid acrossthe river; Court for peaceful settlement. He recalled that similar
(e) navigation should remain unimpeded including disputes have in the past given rise to serious armed
free movementof tourists".
conflicts, endangering the peace and security of the States
The Court, which by the terms of the Joir~tAgreement involved.
between the Parties is eix~poweredto determine the legal He further stated that, given its task, it was inevitable
status of KasikiliISedudu island concludes, in the light of that the Court would choose one of a possible nuiiiber of
the above-mentioned provi:;ionsof the KasaneCommuniquC interpretations of the 1890 Anglo-German Agreeiiient as
and in particular its subparagraph (e) and the !.nterpretation representingthe shared intentionof the Parties regarding the
of that subparagraphBotswanagave before the Court in this
locatioii of tlie boundary and the status of the Island. But
case.,that the Parties have;undertaken to one another that that in so doing, the Court also took into consideration the
there: shall be unimpeded navigation for c:raft of their principle of uti possidetis, a recognized principle of tlie
nationals and flags in the channels of KasikiliISedudu African legalorderregardingboundariesof African States.
Island. As a result, in the southern channel of The Judge added that, this notwithstanding, the Court
KasikiliISedudu Island, the nationals of Namibia, and
vessels flying its flag, art: entitled to, and shall enjoy, a had ruled thatthe nationals and boats flying the flags of the
treatment equal to that accorded by Botswana to its own Republic of Botswana and theRepublic of Namibia should
enjoy equal treatmentin the waters of each other's Statein
nationals and to vessels flying its own flag. Nationals of the accordance with the contemporary principles of the law of
two States,and vessels,whether flyingthe flag of Botswana internationalwatercoursesand the Kasane CornnluniquC.
or of Namibia, shall be subject to the same conditions as In the Judge's view, tlie Judgment should invest the
regards navigation and environmental protection. In the
northern channel, each F'arty shall likewise accord the boundary between the two countries with the necessary
nationals of, and vessels flying the flag of, the:other, equal legal validity and ensured equitable treatment of a shared
nationaltreatment. natural resource.

Declarcrtiorlof Judge Higgins

Judge Higgins states in her declaration that, contrary to
Judge Ranjeva explains how he interprets the reply to what is stated in the Judgment, the Court is not engaged in
Article I of the Special Agreement concerning Articles TI an exerciseof treaty interpretationof words in their ordinary
and I11of the operative pa13of the Judgment r1:latingto the
statusof KasikiliISeduduIsland: meaning. Rather, the Court is applying, in 1997, to a river
1. Given its effect, in terms of allocation of territory, section well understood today, a general term selected by
the Parties in 1890. In so doing, the Court must
the Judgment's choice ofthe northern channel as the main simultaneously have regard to the broad intentions of the
chan.ne1is the least improbablesolution, in the absence of a Parties in 1890 and the state of conteinporary knowledge
systematic coiiiparisonof the two navigation c.hannels;this about thearea in question.
is the reason for the fillclingthat KasikiliISedudu Island
formspart of Botswanatei~itoiy. In her view no great weight should be placed upon
criteria related to navigation, as we now know thehopes of
2. The Kasane CommuniquCcreated legal obligations the Parties regarding navigation to the Zambezi to be
for the two States parties -tothe dispute with regard to the misplaced. Realisin requires us rather to emphasize criteria
enjoiymentand exercise of rights by their nationals in the relevant to theother intentionof the Parties- to arrive at a
relevant area; in addition to navigation andfisl~ingrights in clear frontier- that being an objective which is still
the channel,there is a right of free accessto the:surrounding
waters and to the territoryof KasikiliISedudu Island. obtainablethrough thedecisionof the Court.
The question of general physical appearance is thus
Further, as regards tlie presence of the Masubia on important.Although the Chobe Ridge is the most dominant
KasikiliISeduduIsland, the statementin paragrilph98 of the bank in both channels, year round the northern channel
Judgmentthat: appears to be broader and morevisible. For Judge Higgiiis,
"even if links of allegiance may have existed between iiiany of the factors, while educational and interesting in
the Masubia and the Caprivi authorities, it has not been
themselves,have littlerelevance to the task athand.
established that themembers of this tribe occupied the
Island a titre de souverc~ini,.e.,that they wereexercising to apply these rules and principles independently of the
Separate opinion ofJtrdge Oda
Judge Oda voted in favour of the operative part of the Treaty and to examine Namibia's alternativeclaim that it
Judgment because he supports the Court's determination has title to KasikiliISeduduon the basis of the doctrine of
that the northern channelof the Chobe River constitutes the acquisitiveprescription. Accordingto Judge Kooijmansthis
part of Namibia's claim should have been declared
boundary between Botswana andNamibia. inadmissible, since the Special Agreement precludes the
However, Judge Oda finds it difficult to understand Court from determining the status of the Island
properly the sequence of logic followedby the Court in the independently of the Treaty and that is exactly what the
Judgment. In his view, the Judgment places excessive Court would have done if it had concluded that Namibia's
reliance on the Vienna Convention on theLaw of Treaties, claimisvalid.
whereas, so Judge Oda believes, the case is not one
involving the applicationof that Conventionfor the purpose In the second part of his opinion Judge Kooijmans
expresses theview that the mutual commitmentsthe Parties
of the Court's interpretation of the 1890 Anglo-German have made in the KasaneCommuniquCof 1992with regard
Treaty. In addition, he does not agree with the Court's to the uses of the waters around KasikiliISedudu Island,
approach of viewing the past practice primarily from the clearly reflectrecentdevelopmentsin internationallaw such
standpoint of whether thismight constitute evidenceof any as the principle ofthe equitableandreasonableutilization of
"subsequent agreement"or "subsequent practice"within the shared water resources. The Chobe Riveraround theIsland
meaningof theViennaConvention.
Judge Oda accordingly sketches out the view that he undoubtedly is part of a "watercourse" in the sense of the
1997 Convention on the Non-Navigational Uses of
takes ofthe case. International Watercourses,which defines a watercourseas
After looking at the background to the presentation of a "system of surface waters and ground waters constituting
the case to the Court, Judge Oda takes the view that,as the by virtue of their physical relationship a unita~y whole
compro~niswas not drafted with clarity, the Parties should flowing into a common terminus". Although this
have been asked to clarify their common position as to Convention has not yet entered into force, it embodies
whether they regard the determination of the boundary, certain rules and principles, such as the rule of equitable
which would thenresult in the detern~inationof the legal utilization, which have become well-established in
status ofKasikili/SeduduIsland,as a single issueor whether
international law. The present use of the waters around the
theyregard theseas two separateissues. Island for tourist purposes can hardly be identified as
Judge Oda is of the view that the definition of themain transport by river and is more similar to the uses for non-
channel and, in particular, the identificationof its location,navigai.iona1purposes which are the subject of the 1997
depends largely on scientific knowledge, which the Court Convention. In their future dealings concerning the uses of
should have obtained by seeking the assistance of experts the waters around KasikiliISedudu Island the Parties,
appointedby it. That,however,the Court chosenot to do. therefore, should let themselvesbe guided by the rules and
Judge Oda, however, does not object to the conclusion principles containedin the 1997Convention.

the Court has reached in its choice on its own initiative, Dissenting opinion of Vice-President Weeramantry
without the assistance of independent experts, of the
northern channel as the main channel of the Chobe River; Vice-President Weeramantry,in his dissenting opinion,
and hence, as the boundaryalongthe River betweenthe two took the view thatsince the expressions"main channel" and
States. "Tllalwegdes Ha~rptla~fes" in the 1890Treaty admitted of
Judge Oda agrees with the Court in denying that the more than one interpretation,the sense in which they were
concept of "acquisitiveprescription" has any role to play in understood contemporaneously by the Parties was an
this case. importantaid to their interpretation.

Judge Oda concludes that the northernchannel has, for The regular use of KasikiliISedudu Island by the
the past several decades, as indicated by certain practices Masubiailpeople for overhalf a century afterthe Treaty,the
and in certain survey reports of the region,been regardedas absence of any acknowledgementby them of title in any
the main channel separating the area of the northern and other State, the absence of any objection to such use or of
southern banks in the vicinity of KasikiliISeduduIslandin any assertion of claim by the predecessors in title of
the Chobe River. These factors would,in Judge Oda's view Botswana - all these pointed to a contemporaneous
(whichis contraryto the position takenby the Court),be the understanding, by the parties to the Treaty and their

most pertinent in assisting the Court now to determine the officials, that the Masubia were not crossing national
boundary betweenthe two States. Judge Oda believes that bounda.ries. Consequently, this pointed to the southern
determinationof the boundary wasthe original intention of channelof the Chobeas being the boundary indicatedby the
the Parties in bringing this caseby means of a cornpromisto 1890Treaty. The conduct of governments more than half a
the InternationalCourt of Justice. century later, when background circumstances and power
configurationshad drastically changed, wasnot evidence of
Separate opinion of Jtrdge Kooijmails contemporaneousunderstanding.
The word "agreement" inArticle 31,paragraph3 (b), of
Judge Kooijmans has voted in favour of all parts of the
dispositifof the Judgment.He disagrees, however, withthe the Vienna Convention on the Law of Treaties is not
Court's viewthat the Special Agreementby referring to the confined to a verbal agreement, but covers common
"rules andprinciples of internationallaw" allows the Courtunderstanding which nlay be indicated by action or inaction, application of the treaty which establishes the agreement of
affiinllationor silence. the parties regarding its interpretation"; always keeping in
mind that such agreement may be established not only
The opinion discusses the thalweg principle and the
ambivalence of the scientific criteria and of navigability for through their joint or parallel conduct, but also through the
determiningthe main channel. activity of only one of the parties, where this is assented to
The opinion points out the richness of K.asikili/Sedudtu or not objectedto by the other party.
Island as a wildlife habitat and the legal principles that are 2. Judge Parra-Aranguren considers that the Report of
attractedby this circumstance. Captain Eason (1912); the Joint Report prepared by
Mr. Trollope and Mr. Redman (1948); the exchange of
The opinion goes on to consider the equitable letters which followed between 1948 and 1951; and Mr.
navigational use of boundary rivers, and jud:cial responses
to a boundiuy demarcation which involves the dismantling Renew's Report (1965) lead to the conclusion that the
or division of an ecologically integralunit. Masubia of the Eastern Caprivi were the only tribesmen
It also discusses the scope for equity in boundary who used Kasikili/Sedudu Island at least until 1914; that
delimitation. their occupation of Kasikili/Sedudu Island was peaceful and
public; and that their chiefs "became in N certuii~sense
The differences between treaties dealingwith spheres of agents of the colonial administration", as Botswana
influence and strictly boundary treaties are examined, as acknowledges (see paragraph 85 of his dissenting opinion).
well as the significance of this distinction in the field of Therefore, in his opinion, the subsequent practice of
boundary delimitation.
The question of joint international regime:^to safeguard Germany and Great Britain reflected their understanding
that Kasikili/Sedudu Island formed part of Gelman South
the environmentis discussed in some detail. West Africa and that the southern channel of the Chobe
In the result, Vice-President Weeramantry's view, as River was the "main channel" referred to in Article 111,
expressed in the opinion, is that, while the Island belongs to paragraph 2, of the 1890Anglo-GermanAgreement.
Namibia, a joint international regime between the two 3. Judge Parra-Aranguren states further that st~bsequeilt
countries should be set up to safeguard the environmental practice of the parties to the 1890 Anglo-German
interestsof the Island.
Agreement is only relevant up to the beginning of the First
World War, when the Eastern Caprivi was occupied by
Disserltiilg opiniolt of Judge Fleischhnzler. Rhodesian forces in September 1914; that no subsequent
Judge Fleischhauer has voted against paragraphs 1and 2 practice of the parties to the Treaty was possible when
of the dispositifof the Court's Judgment; he dissents from British troops exercised de facto control over South West
the Court's interpretation of the term"main channel of that Africa; that in 1920 the League of Nations confirmed the
river9'/"Hnuptlaufdieses Flusses"as meaning the northern establishment of the Mandate over South West Africa; and
rather than the southern channel of the Chobe River around that during the existence of the Mandate over South West

Kasikili/Sedudu Island. As the Court does not accept Africa (Namibia) neither of the parties to the 1890 Anglo-
Namibia's argument on prescriptive title to the Island, his German Treaty had competence to recognize, either by
dissent on the interpretation of the tenn "main channel of express agreement or by subsequent practice, that the
that river"/ "Hnuptlaufdieses F~KSS~S affec1:snot only his aforementioned "main channel" of the Chobe River was the
view on the location of the boundary but also his view on northern channel and not the southern channel, since this
the territorial status of the Island. This explains why he new interpretationwould have represented a modification of
voted not only against the first but also against the second the territoiy submitted to the Mandate. Consequently, the
paragraph of the disposit$ Judge Fleischhauer voted, original understanding was maintained and for this reason
however, in favour of the third paragraph. Judge Parra-Aranwren concludes that Kasikili/Sedudu

While concurring with what the Court had to say about Island forms part of Namibia and thatthe southern channel
the role of prescription in the case, Judge Fleischhauer of the Chobe River is the "main channel" referred to in
makes ailadditionalremark on this subject. Article 111, paragraph 2, of the 1890 Anglo-German
Agreement.
Disseiztil~gopinion of.JzldgeParra-Ai.atzgzrrei~
1. Judge Parra-Aranguren observes, as does the Disseiltil~gopiitiott oj'JtddgeRezek
Judgment, that Botswana and Namibia are not in agreement In his dissenting opinion Judge Rezek emphasizes the
ambiguities in the geography of the Kasikili/Sedudu area.
as to the meaning of the phrase "the centre of tlze main He criticizes the arguments based on navigability, visibility
cllannel(der Thnlwegder:Hauptlazrfes)of tl~le ChobeRiver" and the natural prolongation of the river at the bifurcation.
found in Article 111, aragraph 2, of the 1890Anglo-German He interprets the Anglo-Gerinan Treaty of 1890in the light
Agreement; that the Treaty itself does not define it; that no of history, taking into account the practice of the parties, the
other of its provisions provide by implication guidelines
useful for this purpose:; and that for this reason such principle of the equitable apportionment of the resources of
expression has to be interpreted according to customary a watercourse, the cartography and the de facto occupation
int~:rnationallaw as expressed in Article 31 of the Vienna of the Island by the Caprivi Masubia. He finds that priority
must go to those elenlents which place the boundary in the
Convention on the Law of Treaties of 23 May 1969. southern channel and accord Namibia sovereignty over
Therefore, in accordancewith letter (b) of said Article 31, it Kasikili/Sedudu.
is necessary to examine "any subsequent practice in the - " "

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