The Authority of Advisory Opinions in Contentious Proceedings

Abstract The International Court of Justice (ICJ, the Court) increasingly addresses major regional and global conflicts and crises. In contentious proceedings, its limited jurisdiction—regarding both subject-matter and matters affecting third States—often confines the Court to examining a small portion of the actual dispute between the parties. In advisory proceedings, by contrast, the Court faces no such constraints when determining the legal positions of individual States. This article argues that legal determinations made in advisory opinions can, in principle, be relied on as ‘givens’ in subsequent contentious proceedings where the Court would otherwise be prevented from making such determinations. The Court’s advisory and contentious jurisdictions are both built on consent, which is required to protect States’ sovereignty from exercises of the Court’s authority. If the Court exercises its authority in an advisory opinion by determining the legal position of a State, it removes sovereignty concerns regarding this determination for subsequent contentious proceedings. The significant practical challenges in relying on legal determinations from advisory opinions as ‘givens’ are most likely to be overcome in relation to determinations of status, rather than for establishing specific internationally wrongful acts. ‘Givens’ from advisory opinions are thus not a general workaround to the limitations in the ICJ’s contentious jurisdiction. Still, relying on determinations from advisory opinions in subsequent contentious proceedings invites the Court to enter into an intricate dialogue between its two forms of jurisdiction, a dialogue which may further intertwine them and thereby enhance coherence in the ICJ’s exercise of its judicial function.