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World Court Digest

I. Substantive International Law - First Part
2.1. General Questions
2.1.5. Relation between the Sources of International Law

¤ Maritime Delimitation in the Area
between Greenland and Jan Mayen,
Judgment of 11 September 1992,
Judgment, I.C.J. Reports 1993, p. 38

[pp. 58-59] 46. The fact that it is the 1958 Convention which applies to the continental shelf delimitation in this case does not mean that Article 6 thereof can be interpreted and applied either without reference to customary law on the subject, or wholly independently of the fact that a fishery zone boundary is also in question in these waters. The Anglo-French Court of Arbitration in 1977 placed Article 6 of the 1958 Convention in the perspective of customary law in the much-quoted passage of its Decision, that:

"the combined 'equidistance-special circumstances rule', in effect, gives particular expression to a general norm that, failing agreement, the boundary between States abutting on the same continental shelf is to be determined on equitable principles" (United Nations, Reports of International Arbitral Awards (RIAA), Vol. XVIII, p. 45, para. 70).

If the equidistance-special circumstances rule of the 1958 Convention is, in the light of this 1977 Decision, to be regarded as expressing a general norm based on equitable principles, it must be difficult to find any material difference - at any rate in regard to delimitation between opposite coasts - between the effect of Article 6 and the effect of the customary rule which also requires a delimitation based on equitable principles. The Court in the case concerning the Continental Shelf (Libyan Arab Jamahirya/Malta), where it was asked only to delimit the continental shelf boundary, expressed the view that

"even though the present case relates only to the delimitation of the continental shelf and not ot that of the exclusive economic zone, the principles and rules underlying the latter concept cannot be left out of consideration";

that "the two institutions - continental shelf and exclusive economic zone - are linked together in modern law"; and that the result is "that greater importance must be attributed to elements, such as distance from the coast, which are common to both concepts" (I.C.J. Reports 1985, p. 33, para. 33).

[pp. 134-135 S.O. Shahabuddeen] The extent to which the interpretation and application of a treaty must take account of the subsequent evolution of the law has been much debated 1. That such account must be taken at any rate in the case of jurisdictional and law-making treaty provisions seems clear (Aegean Sea Continental Shelf I.C.J. Reports 1978, pp. 32-34, paras. 77-80; and, ibid., pp. 68-69, and footnote 1 to p. 69, Judge de Castro, dissenting). More particularly, later developments in customary international law do need to be taken into account in applying the provisions of the 1958 Convention (Anglo-French Arbitration, 1977, RIAA, Vol. XVIII, p. 37, para. 48. And see Gulf of Maine, I.C.J. Reports 1984, p. 291, para. 83).

Thus, account must be taken of the fact that Article 76 of the 1982 Convention has introduced a new definition of the outer limit of the continental shelf. There is little dispute that this replaces the different definition set out in Article l of the 1958 Convention (Tunisia/Libya, I.C.J. Reports 1982, pp. 114-115, paras. 52-53, Judge Jiménez de Aréchaga, separate opinion). But exactly how this has come about is less clear. Differences between two rules relating to the same matter may sometimes be resolved by regarding the rules as being really complementary to each other (Electricity Company of Sofia and Bulgaria, P.C.I.J., Series A/B, No. 77, pp. 75 ff.; and see, ibid., pp. 136 ff., Judge De Visscher, separate opinion). In case of irreconciable conflict (as in this case), an integrated legal system would provide some method of determining which rule ultimately prevails; for the same facts cannot at one and the same time be subject to two contradictory rules. Judge Anzilotti did not seem to entertain that possibility when he said,

"[i]t is clear that, in the same legal system, there cannot at the same time exist two rules relating to the same facts and attaching to these facts contradictory consequences ..." (ibid., p. 90, separate opinion. And see, ibid., p. 105, Judge Urrutia, dissenting. Cf. I.C.J. Pleadings, Nuclear Tests, Vol. I, p. 238, Mr. Elihu Lauterpacht, Q.C.).

How has the problem been resolved in this case? The substitution of the 1982 definition of the continental shelf for the 1958 definition could not have come about through a treaty displacement, since the 1982 Convention is not in force. Could it have come about through the customary international law effect of the new definition on the old? At least in relation to the normal continental shelf of 200 miles (which is what this opinion is concerned with), the better view would seem to be that the new limit operates at the level of customary international law. If the 1958 rule is regarded solely as a treaty rule, the position is that "a later custom ... prevails over an earlier treaty ..." (Paul Reuter, Introduction to the Law of Treaties, 1989, pp. 107-108, para. 216). But, of course, the same rule may exist autonomously under customary international law as well as under conventional international law 2. The limit prescribed by Article l of the 1958 Convention was regarded as being also expressive of customary international law (Tunisia/Libya, I.C.J. Reports 1982, p. 74, para. 101, referring to the North Sea cases). Considered on this basis, it would clearly be superseded by the different limit prescribed by later customary international law as expressed in Article 76 of the 1982 Convention.

Thus, whether the limit prescribed by Article 1 of the 1958 Convention is treated solely as a treaty rule or also as a rule of customary international law, it falls to be regarded as having been modified by Article 76 of the 1982 Convention applying as customary international law. Both Parties in fact proceeded on the basis that the applicable limit is 200 miles in accordance with contemporary customary international law.

But I do not consider that there has been any modification of the delimitation provisions of the 1958 Convention. In the North Sea cases, the Court said, "Articles l and 2 of the Geneva Convention do not appear to have any direct connection with inter-State delimitation as such" (I.C.J. Reports 1969, p. 40, para. 67). The delimitation procedures of Article 6 were not dependent on the particular outer limits fixed for the continental shelf. Subsequent changes in those limits should not affect the continued applicability of the procedures. No doubt, as remarked above, any application of the delimitation principles of the 1958 Convention would have to take account of the evolution of the law relating to the subject-matter to which the application is directed; but I cannot see that this calls for any modification of the delimitation principles themselves.

1Footnote omitted.
2Footnote omitted.