The author discusses the effects of the res judicata rule as regards jurisdictional decisions of the International Court of Justice. He finds that there exists a special position of a judgment on preliminary objection in respect to both aspects of the res judicata rule– its binding force and finality. A perception of distinct relativity of a jurisdictional decision of the Court, expressing its interlocatory character pervades, in his opinion, the body of law regulating the Court’s activity. Preliminary objections as such do not exhaust objections to the jurisdiction of the Court, as evidenced by non-preliminary objections to the jurisdiction of the Court giving rise to the application of the principle compétence de la compétence understood in the narrow sense. With regard to the binding force of a judgment on preliminary objections, it does not create legal obligations stricto sensu. The author finds that the relative character of jurisdictional decisions of the Court as compared with a judgment on the merits is justified on a number of grounds.