This article shows that the Tribunal in the Chagos Marine Protected Area Arbitration between Mauritius and the United Kingdom has contributed considerably to the creeping expansion of compulsory jurisdiction of courts and tribunals established under Part XV of the United Nations Convention on the Law of the Sea (UNCLOS). The Tribunal has employed three techniques to do so. First, it has read down the jurisdictional precondition to exchange views in Article 283(1) of the UNCLOS; second, it has expanded the limited scope of compulsory subject-matter jurisdiction under section 2 of Part XV by broadening the meaning of the phrase ‘any dispute concerning the interpretation or application of this Convention’ to include incidental, related—and through the backdoor of a balancing exercise—even extraneous disputes; and, third, it has restricted the limitations and exceptions to compulsory jurisdiction in Articles 297 and 298 of the UNCLOS. Few would have predicted in 1982 that a Part XV court or tribunal would—within the context of such a balancing exercise—ever find that a colonial era undertaking created binding legal obligations under international law and that the United Kingdom was obliged to return the Chagos Archipelago to Mauritius when no longer needed for defence purposes. The Tribunal's expansive reading of the jurisdictional provisions in Part XV opens up the possibility of future rulings, albeit incidentally, on issues that have little to do with the law of the sea.

At the time the United States withdrew from participation in the Nicaragua case at the International Court of Justice, the US government expressed concern that ‘the course on which the Court may now be embarked could do enormous harm to it as an institution and to the cause of international law’. This essay examines whether or to what extent the anticipated negative effects came to pass. It concludes that dire predictions of harm to the Court were overstated. Twenty-five years later, the rate at which states accept the Court's jurisdiction has held steady. Only a few states have added jurisdictional reservations concerning military activities. The mix of cases being brought to the Court has shifted towards a more representative distribution. States are generally complying with the Court's decisions, though some compliance problems remain. The most serious negative impact has been on the willingness of the United States (still the Court's most active litigant) to participate fully in international dispute settlement.

States can accept the jurisdiction of the International Court of Justice with respect to all or certain categories of legal disputes by means of unilateral declarations. This article examines the reservations to the acceptance of the compulsory jurisdiction that states include in such declarations. It reviews the practice of states and traces the trends in drafting and adopting reservations. It also analyzes the jurisprudence of the Permanent Court of International Justice and the International Court of Justice in relation to the interpretation of various reservations, particularly in recent cases, illustrating the effectiveness or ineffectiveness of different types of reservations.

This paper is concerned with the denunciation of declarations of acceptance of the compulsory jurisdiction of the International Court of Justice under the Optional Clause and the impact that the 1984 Judgment of the Court in the jurisdictional phase of the Nicaragua case may have had upon it. In this decision the Court found that the principle of good faith is of paramount importance in the legal regime of the Optional Clause and introduced in that regime the element of a ‘reasonable time’ for the denunciation of declarations of indefinite duration and silent as to termination. The relevant passage of the Judgment is discussed with a view to determine the contours of this requirement and the ways it may operate in practice.