This chapter addresses the Court’s jurisdiction in contentious cases and its jurisdiction in advisory opinions, using specific examples from the Court’s judgments and opinions. It considers whether a novel approach is needed to confer on the Court compulsory jurisdiction across a wider range of disputes.

The chapter traces the origins of the ICJ in its predecessor, the PCIJ, and then considers the Court’s core functions: deciding the disputes submitted to it and exercising its advisory functions. It also critically examines the Court’s functions in finding and developing the law, and in maintaining international peace and security.

The procedural rules on dispute settlement are primarily contained in Part XV UNCLOS. These rules set out the conditions for UNCLOS tribunals to establish and exercise their compulsory jurisdiction hear contentious disputes. In addition to disputes between States, UNCLOS also grants the Seabed Disputes Chamber advisory jurisdiction pursuant to Article 191 UNCLOS. ITLOS as a full tribunal, however, has also found that it may exercise advisory jurisdiction despite the absence of an explicit provision to that effect under UNCLOS and the ITLOS Statute. This Chapter critically examines UNCLOS tribunals’ decisions relating the conditions for the establishment of compulsory jurisdiction in contentious proceedings under Part XV and the establishment of advisory jurisdiction of both the SDC and ITLOS as a full tribunal, in order to determine the extent to which UNCLOS tribunals have clarified the procedural law under the Convention.