The judgment on preliminary objections in Croatia v. Serbia provided closure to fifteen years of controversy as to whether Serbia had access to the ICJ from 1992 to 2000, a period in which Serbia was involved in three sets of cases before the Court. At the heart of the controversy lay the question of the status of Serbia vis-à-vis the United Nations following the disaggregation of the former Yugoslavia. Taking as a starting point the series of cases relating to the application of the Genocide Convention and the legality of use of force by NATO states, this article revisits the issue of continuation of membership in the United Nations. It begins by discussing the problems posed by the “horizontal inconsistency” among the Court’s jurisdictional findings, which implied that Serbia had and did not have access to the Court in the relevant period. It then offers a critique of the ICJ’s decision in Legality of Use of Force, and proposes an approach to continuation of membership in the UN that would have allowed the Court not only to avoid inconsistency, but also to clarify an important question of UN law. The argument to be advanced is that, according to the soundest interpretation of the UN Charter, a de facto exercise of membership may produce valid legal effects.