The International Court of Justice (ICJ) plays a part in the peaceful settlement of international disputes, in furtherance of the first purpose of the United Nations: "to bring about by peaceful means, and in conformity with the principles of justice and international law, adjustment or settlement of international disputes or situations which might lead to a breach of the peace". The Court fulfils this role not only by its function of adjudication of international disputes - disputes which, if unresolved, might lead to a breach of the peace but, far more often, disputes which are an element of the routine interaction of international relations. On occasion, the Court's judicial activity is complemented by political methods of dispute settlement by the parties to the dispute and by UN organs other than the Court, which is "the principal judicial organ of the United Nations".
The ICJ is not a substitute for the UN Security Council. The treasured ideal of the early peace movement of this century - that resort to international adjudication would prevent the outbreak of war - proved to be unrealistic. Far from international adjudication generally preventing war, it is peace that conduces to the settlement of inevitable international disputes by adjudication. The Permanent Court of International Justice flourished in the 1920s, in a decade of detente, and declined in the 1930s, with the rise of international tensions provoked by the Axis Powers. Since the end of the cold war, the ICJ has had a heavier docket than ever before.
International disputes often comprise various aspects: political, legal, economic, social and other. Some disputes may be best settled if legal and other methods of settlement are deployed in a complementary way; at the same time, a court - not least an international court - must act in response solely to legal considerations. The ICJ has shown itself able to work together with political organs of the United Nations while preserving its judicial integrity. At times, recourse to the Court has promoted a negotiated settlement of the dispute by the parties themselves. Indeed, on occasion, the mere threat of recourse to the Court,express or implied, by one party to a dispute has moved the other party towards a negotiated solution.
The ICJ and the Security Council may act as partners in the maintenance of international peace and security. While the UN Charter confers on the Council "primary responsibility for the maintenance of international peace and security", the Court may and on several occasions has become involved in the same dispute. The Court then deals with and resolves legal aspects of the dispute; the Security Council handles the political aspects.
This complementarity was illustrated by concurrent recourse to both the Council and the Court when United States diplomats were held hostage in Teheran. It was confirmed again in the case concerning Military and Paramilitary Activities in and against Nicaragua, where the ICJ held that: "The Council has functions of a political nature assigned to it, whereas the Court exercises purely judicial functions. Both organs can, therefore, perform their separate but complementary functions with respect to the same events."
There have been a number of other instances in which the Court and the Security Council acted together. The conflict in Bosnia and Herzegovina is one of them. While the Council was seeking to achieve a political solution to the conflict. Bosnia brought to the Court the grave legal question of whether the Federal Republic of Yugoslavia was acting in breach of the Convention on the Prevention and Punishment of the Crime of Genocide. The Court. in an Order indicating provisional measures (i.e., an interim injunction), called on Yugoslavia to "take all measures within its power to prevent commission of the crime of genocide". The Council, in turn, took note of this Order, which was followed by another reiterating provisional measures and a judgment rejecting Yugoslavia's objections to the Court's jurisdiction. …