The objects and effects of non-party intervention before the International Court of Justice

Abstract

AbstractThe International Court of Justice recognized the legitimacy of ‘non-party intervention’ under Article 62 of the Statute in its 1990 landmark decision on Nicaragua’s intervention in the Land, Island and Maritime Frontier Dispute (El Salvador v. Honduras). Such form of intervention ‘is not intended to enable a third State to tack on a new case, to become a new party, and so have its own claims adjudicated by the Court’. Its purpose is ‘protecting a State’s “interest of a legal nature” that might be affected by a decision in an existing case’. Whereas non-party intervention under Article 62 now forms part of the law in action within the Court’s system, its precise features and regime remain uncertain. Doubts concern the identification of its precise objects and the potential binding effects for a non-party intervener of the judgment issued between the original parties. The present article explores these issues in the light of the Court’s case law and state practice. It demonstrates that non-party intervention can have various potential objects, depending on how the intervener intends to influence the future judgment between the original parties. Building on the identification of these objects, it then questions the traditional construction denying any binding effect of the decision for a non-party intervener and argues that a judgment issued following intervention is binding as between the original parties and the intervener in so far as this judgment, whether expressly or by implication, decides issues related to the object of intervention.