International law can help reduce tensions and contribute to the preservation of peace only when the states concerned want to use it for this purpose. When a state is prepared to resort to armed force to get what it wants, it can be restrained, if at all, only by superior power. The enforcement of peace is, under Chapter VII of the Charter of the United Nations, a responsibility of the Security Council. As already pointed out, the Council has the power, though not the duty, to take measures to give effect to the judgments of the Court; it also has the power, without prior or subsequent recourse to the Court, to determine that a threat to the peace, a breach of the peace or an act of aggression exists, and to decide upon the measures necessary to maintain or restore international peace and security. The Security Council may, in its discretion, request an advisory opinion of the Court on any legal question that may arise in the performance of its functions, but the Council's decisions are not judicially reviewable as of right. The seemingly vast and ill-defined powers of the Security Council are in reality very much limited by the requirement of the unanimity of its permanent members for action on other than procedural matters and by the lack of obligation on the part of the Members of the United Nations to supply military forces to carry out the Council's decisions in the absence of a special agreement.
At present the Court has very little to do with the enforcement of peace. Can it play a greater role in the future? Suggestions for expanding the functions of the Court in this connection may be divided into those which favor judicial review of the actions of the political organs of the United Nations, and those which envisage a system of world security based on judicial determinations of the breaches of the law.