CHAPTER EIGHT Treaty System
8.2 Formation, Performance, Cessation
On February 3, 2006, the ICJ decided the Case Concerning Armed Activities on the Territory of the Congo, reprinted at 45 I.L.M. 562 (2006). Rwanda's reservation to the Genocide Convention (case para. 38) provides: "The Rwandese Republic does not consider itself as bound by Article IX of the Convention." That Article states (case para. 28): "Disputes between the Contracting Parties relating to the interpretation, application or fulfilment of the present Convention, including those relating to the responsibility of a State for genocide or for any of the other acts enumerated in article III, shall be submitted to the International Court of Justice at the request of any of the parties to the dispute." At case para. 66, the ICJ refers to its earlier decision that "reservations are not prohibited under the Genocide Convention" (see textbook p. 364-366).
.....In this case (para. 67), the ICJ decided: "Rwanda's reservation to Article IX of the Genocide Convention bears on the jurisdiction of the Court, and does not affect substantive obligations relating to acts of genocide themselves under that Convention. [Thus] . . . the Court cannot conclude that the reservation of Rwanda in question, which is meant to exclude a particular method of settling a dispute . . . is to be regarded as being incompatible with the object and purpose of the Convention."
.....The ICJ concluded (case para. 127): "The Court is precluded by its Statute from taking any position on the merits of the claims made by the DRC. However, as the Court has stated on numerous previous occasions, there is a fundamental distinction between the question of the acceptance by States of the Court's jurisdiction and the conformity of their acts with international law. Whether or not States have accepted the jurisdiction of the Court, they are required to fulfil their obligations under the United Nations Charter and the other rules of international law, including international humanitarian and human rights law, and they remain responsible for acts attributable to them which are contrary to international law.
.....Judge Koroma's dissent (dissent para. 14, 19, 22, and 24) argues in favor of jurisdiction over Rwanda for its genocidal acts in the DRC, although the latter did not object to Rwanda's reservation, in the following terms:

[T]he fact that a State does not object to such a reservation at the time it is made is not, in my view, of dispositive significance, given that States are often remiss in fulfilling their duties of objecting to reservations which they consider invalid. Moreover, the failure of a State to object should not be regarded as determinative in the context of human rights treaties like the Genocide Convention that are not based on reciprocity between States but instead serve to protect individuals and the international community at large (italics added).
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.....This is all the more so given the principles underlying the Convention, as well as the gravity of the present case, in which 3,500,000 Congolese citizens are alleged to have been massacred on grounds of ethnicity.
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.....This point is of particular cogency in this case concerning Rwanda, a State where genocide took place and which justifiably called on the United Nations Security Council to set up an international criminal tribunal to try those who committed the crime against a section of its population. It will thus not be in keeping with the spirit and objective of the Convention to refuse to allow judicial consideration of the allegation of genocide perpetrated in another country.
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.....The allegation involving the commission of genocide is far too serious a matter to be allowed to escape judicial scrutiny by means of a procedural device. The nature of the Convention and gravity of the allegation dictate that, wherever possible, it must be subject to judicial scrutiny.

Judge ad hoc Dugard's seperate opinion adds (para. 3): "The DRC has sought to invoke the jurisdiction of the Court on the basis of a number of arguments premised on the violation of peremptory norms (jus cogens) by Rwanda. These arguments, in essence, may be reduced to two. First, the allegation of the violation of a norm of jus cogens per se confers jurisdiction on the Court. Secondly, where a violation of a norm of jus cogens is alleged, the respondent State cannot raise a reservation to the Court's jurisdiction to defeat that jurisdiction. In such a case, jus cogens in effect trumps the reservation."