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World Court Digest

I. Substantive International Law - First Part
7.8. Interpretation

¤ Case Concerning Sovereignty over
Pulau Ligitan and Pulau Sipadan
(Indonesia v. Malaysia)
Judgment of 17 December 2002

[pp. ] 37. The Court notes that Indonesia is not a party to the Vienna Convention of 23 May 1969 on the Law of Treaties; the Court would nevertheless recall that, in accordance with customary international law, reflected in Articles 31 and 32 of that Convention:

“a treaty must be interpreted in good faith in accordance with the ordinary meaning to be given to its terms in their context and in the light of its object and purpose. Interpretation must be based above all upon the text of the treaty. As a supplementary measure recourse may be had to means of interpretation such as the preparatory work of the treaty and the circumstances of its conclusion.” (Territorial Dispute (Libyan Arab Jamahiriya/Chad), Judgment, I.C.J. Reports 1994, pp. 21-22, para. 41; see also Maritime Delimitation and Territorial Questions between Qatar and Bahrain (Qatar v. Bahrain), Jurisdiction and Admissibility, Judgment, I.C.J. Reports 1995, p. 18, para. 33; Oil Platforms (Islamic Republic of Iran v. United States of America), Preliminary Objection, Judgment, I.C.J. Reports 1996 (II), p. 812, para. 23; Kasikili/Sedudu Island (Botswana/Namibia), Judgment, I.C.J. Reports 1999 (II), p. 1059, para. 18.)

Moreover, with respect to Article 31, paragraph 3, the Court has had occasion to state that this provision also reflects customary law, stipulating that there shall be taken into account, together with the context, the subsequent conduct of the parties to the treaty, i.e., “any subsequent agreement” (subpara. (a)) and “any subsequent practice” (subpara. (b)) (see in particular Legality of the Use by a State of Nuclear Weapons in Armed Conflict, Advisory Opinion, I.C.J. Reports 1996 (I), p. 75, para. 19; Kasikili/Sedudu Island (Botswana/Namibia), Judgment, I.C.J. Reports 1999 (II), p. 1075, para. 48).

Indonesia does not dispute that these are the applicable rules. Nor is the applicability of the rule contained in Article 31, paragraph 2, contested by the Parties.

[p. ] 53. In view of the foregoing, the Court does not consider it necessary to resort to supplementary means of interpretation, such as the travaux préparatoires of the 1891 Convention and the circumstances of its conclusion, to determine the meaning of that Convention; however, as in other cases, it considers that it can have recourse to such supplementary means in order to seek a possible confirmation of its interpretation of the text of the Convention (see for example Territorial Dispute (Libyan Arab Jamahiriya/Chad), I.C.J. Reports 1994, p. 27, para. 55; Maritime Delimitation and Territorial Questions between Qatar and Bahrain (Qatar v. Bahrain), Jurisdiction and Admissibility, Judgment, I.C.J. Reports 1995, p. 21, para. 40).

[pp. ] 88. The Court would begin by recalling, as regards the legal value of maps, that it has already had occasion to state the following:

“maps merely constitute information which varies in accuracy from case to case; of themselves, and by virtue solely of their existence, they cannot constitute a territorial title, that is, a document endowed by international law with intrinsic legal force for the purpose of establishing territorial rights. Of course, in some cases maps may acquire such legal force, but where this is so the legal force does not arise solely from their intrinsic merits: it is because such maps fall into the category of physical expressions of the will of the State or States concerned. This is the case, for example, when maps are annexed to an official text of which they form an integral part. Except in this clearly defined case, maps are only extrinsic evidence of varying reliability or unreliability which may be used, along with other evidence of a circumstantial kind, to establish or reconstitute the real facts.” (Frontier Dispute (Burkina Faso/Republic of Mali), Judgment, I.C.J. Reports 1986, p. 582, para. 54; Kasikili/Sedudu Island (Botswana/Namibia), Judgment, I.C.J. Reports 1999 (II), p. 1098, para. 84).

In the present case, the Court observes that no map reflecting the agreed views of the parties was appended to the 1891 Convention, which would have officially expressed the will of Great Britain and the Netherlands as to the prolongation of the boundary line, as an allocation line, out to sea to the east of Sebatik Island.

89. In the course of the proceedings, the Parties made particular reference to two maps: the map annexed to the Explanatory Memorandum appended by the Netherlands Government to the draft Law submitted to the States-General for the ratification of the 1891 Convention, and the map annexed to the 1915 Agreement. The Court has already set out its findings as to the legal value of these maps (see paragraphs 47, 48 and 72 above).

90. Turning now to the other maps produced by the Parties, the Court observes that Indonesia has submitted a certain number of maps published after the 1891 Convention showing a line continuing out to sea off the eastern coast of Sebatik Island, along the parallel of 4° 10' latitude north. These maps include, for example, those of Borneo made by Stanford in 1894, in 1903 and in 1904, and that of 1968 published by the Malaysian Ministry of Lands and Mines to illustrate oil-prospecting licences.

The Court notes that the manner in which these maps represent the continuation out to sea of the line forming the land boundary varies from one map to another. Moreover, the length of the line extending out to sea varies considerably: on some maps it continues for several miles before stopping approximately halfway to the meridians of Ligitan and Sipadan, whilst on others it extends almost to the boundary between the Philippines and Malaysia.

For its part, Malaysia has produced various maps on which the boundary line between the British and Dutch possessions in the region stops on the eastern coast of Sebatik Island. These maps include the map of British North Borneo annexed to the 1907 Exchange of Notes between Great Britain and the United States, the Dutch map of 1913 representing the Administrative Structure of the Southern and Eastern Borneo Residence, and the map showing the 1915 boundary line published in the Official Gazette of the Dutch Colonies in 1916.

The Court however considers that each of these maps was produced for specific purposes and it is therefore unable to draw from those maps any clear and final conclusion as to whether or not the line defined in Article IV of the 1891 Convention extended to the east of Sebatik Island. Moreover, Malaysia was not always able to justify its criticism of the maps submitted by Indonesia. Malaysia thus contended that the line shown on the Stanford maps of 1894, 1903 and 1904, extending out to sea along the parallel of 4° 10' latitude north, corresponded to an administrative boundary of North Borneo, but could not cite any basis other than the 1891 Convention as support for the continuation of that State’s administrative boundary along the parallel in question.

91. In sum, with the exception of the map annexed to the 1915 Agreement (see paragraph 72 above), the cartographic material submitted by the Parties is inconclusive in respect of the interpretation of Article IV of the 1891 Convention.