The ICJ is composed of fifteen judges elected for nine years by the U.N. General Assembly and the U.N. Security Council from a list of persons nominated by the nations groups in the Permanent Court of Arbitration.
All the members of the United Nations automatically become parties to the Court’s statute. Even Non-UN members may also become parties to the Court’s statute.
However, being a party to the statute does not automatically confer the jurisdiction of the Court over disputes involving those parties. Jurisdiction of the Court basically involves two types of issues: contentious issues and advisory opinions.
Jurisdiction is often a crucial question for the Court in contentious cases. The key principle is that the ICJ has jurisdiction only on the basis of consent.
An advisory opinion is a function of the Court open only to specified United Nations bodies and agencies. The Court’s advisory opinions are only consultative in nature, but even then it is influential and widely respected.
While deciding cases, the court applies international law like international conventions, international customs, and the general principles of law recognized by civilized nations, the precedent, and also teachings of the jurists.