Since States alone are entitled to appear before the Court, public (governmental) international organizations cannot be parties to a case before it. However, a special procedure, the advisory procedure, is available to such organizations and to them alone. This procedure is available to five United Nations organs, fifteen specialized agencies and one related organization.
Though based on contentious proceedings,advisory proceedings have distinctive features resulting from the special nature and purpose of the advisory function.
Advisory proceedings begin with the filing of a written request for an advisory opinion addressed to the Registrar by the United Nations Secretary-General or the director or secretary-general of the entity requesting the opinion. In urgent cases the Court may take all appropriate measures to speed up the proceedings. To assemble all the necessary information about the question submitted to it, the Court is empowered to hold written and oral proceedings.
A few days after the request has been filed, the Court draws up a list of the States and international organizations that are likely to be able to furnish information on the question before the Court. Usually, the States listed are the member States of the organization requesting the opinion, while sometimes the other States to which the Court is open in contentious proceedings are also included. As a rule, organizations and States authorized to participate in the proceedings may submit written statements, followed, if the Court considers it necessary, by written comments on others’s statements. These written statements are generally made available to the public at the beginning of the oral proceedings, if the Court considers that such proceedings should take place.
Contrary to judgments, and except in rare cases where it is expressly provided that they shall have binding force (for example, as in the Convention on the Privileges and Immunities of the United Nations, the Convention on the Privileges and Immunities of the Specialized Agencies of the United Nations, and the Headquarters Agreement between the United Nations and the United States of America), the Court’s advisory opinions are not binding. The requesting organ, agency or organization remains free to decide, as it sees fit, what effect to give to these opinions.
Despite having no binding force, the Court’s advisory opinions nevertheless carry great legal weight and moral authority. They are often an instrument of preventive diplomacy and help to keep the peace. In their own way, advisory opinions also contribute to the clarification and development of international law and thereby to the strengthening of peaceful relations between States.