The International Court of Justice is the primary judicial organ of the United Nations. All members of the United Nations are automatically parties to the ICJ, but a state that is not a UN member may join the Court on conditions determined by the General Assembly. 

The International Court of Justice has a twofold function. One is the settlement of disputes between states, not individuals, on the basis of international law. The Court can only deal with a dispute when the States concerned have recognized its jurisdiction. The other function is the delivery of advisory opinions on legal questions at the request of specifically authorized international organs. 

For further information on the International Court of Justice, see DagDok: section International Court of Justice.