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World Court Digest

I. Substantive International Law - First Part
7.4. Reservations

¤ Legality of Use of Force
(Yugoslavia v. United States of America),
Request for the Indication of
Provisional Measures,
Order of 2 June 1999

[p. D.O. Kreca ] 9. ... In its Judgment of 11 July 1996 in the Genocide case, the Court stated "[i]t follows that the rights and obligations enshrined by the Convention are rights and obligations erga omnes" (Application of the Convention on the Prevention and Punishment of the Crime of Genocide, Preliminary Objections, Judgment, I.C.J. Reports 1996, p. 616, para. 31).

It is obvious that the first and second of the "understandings" lodged by the United States are actually reservations incompatible with the object and purpose of the Genocide Convention (Jordan Paust, "Congress and Genocide: They're not going to get away with it", Michigan Journal of International Law, Vol. 11, 1989-1990, pp. 92-98).


"At least Arts. II, III and IV of the Genocide Convention, which are agreed to codify customary international law, therefore represent jus cogens. This means that no derogation from these provisions is permissible, so long as the international community of States as a whole does not develop a new rule. Therefore, to the extent that any reservations to the Genocide Convention purport to derogate from the scope or nature of any State's obligations in respect of genocide, as set out in the core provisions of the Genocide Convention, those reservations would be void under the jus cogens doctrine" (M. M. Sychold, "Ratification of the Genocide Convention: The legal effects in light of reservations and objections", Schweizerische Zeitschrift für internationales und europäisches Recht, 4/1998, p. 551).

10. The norms of ius cogens are of an overriding character; thus, they make null and void any act, be it unilateral, bilateral or multilateral, which is not in accordance with them. Such a logical conclusion based on the peremptory or absolutely binding nature of ius cogens norms, expressing in the normative sphere the fundamental values of the international community as a whole, have been confirmed in the North Sea Continental Shelf cases. In those cases, the Court was faced with the contention that the "equidistance principle" contained in Article 6 of the 1958 Geneva Convention an the Continental Shelf had become tractu temporis a rule of customary international law. The Court in its Judgments said:

"it is characteristic of purely conventional rules and obligations that, in regard to them, some faculty of making unilateral reservations may, within certain limits, be admitted; - whereas this cannot be so in the case of general or customary law rules and obligations which, by their very nature, must have equal force for all members of the international community, and cannot therefore be the subject of any right of unilateral exclusion exercisable at will by any one of them in its own favour. Consequently, it is to be expected that when, for whatever reason, rules or obligations of this order are embodied, or are intended to be reflected in certain provisions of a convention, such provisions will figure amongst those in respect of which a right of unilateral reservation is not conferred, or is excluded." (North Sea Continental Shelf, Judgment, I.C.J. Reports 1969, pp. 38-39, para. 63.)

Leaving aside some conceptual confusion in this passage regarding the relation between rules of general international law and norms constituting corpus iuris cogentis, it appears that the Court was quite clear that rules applying to purely conventional rules and obligations cannot be per analogiat applied to norms having the character of ius cogens.

The only possible way of excluding nullity effects in regard to the United States' reservation to Article IX of the Genocide Convention, may lie in the interpretation that nullity affects only "understandings" and that it has no legal consequences for the reservation itself.

Such an interpretation would run counter to the fundamental rule of inseparability of the acts, be it unilateral, bilateral or multilateral, conflicting with a norm belonging to corpus iuris cogentis. In its commentary to Article 44 (5) of the Vienna Convention an the Law of Treaties, the International Law Commission stated unequivocally:

"rules of jus cogens are of so fundamental a character that, when parties conclude a treaty which conflicts in any of its clauses with an already existing rule of jus cogens, the treaty must be considered totally invalid" (YILC, 1966, II, p. 239, para. 8).

As Sir Gerald Fitzmaurice pointed out:

"there are the cases in which overriding rules of ius cogens produce a situation of irreducible obligation and demand that illegal action be ignored and not allowed to affect the obligations of other States" (G. Fitzmaurice, "The Law and Procedure of the International Court of Justice", 1954-1959, 35 BYBIL, 1955, p. 122).

Accordingly, the overriding character of norms of ius cogens which are the very basis of the international community as a whole, makes impossible separability of an act of the United States containing both reservations and "understandings" which are in conflict with the norm having a peremptory nature.