The Gabčíkovo-Nagymaros Judgment is among the most influential pronouncements of the International Court of Justice. While the Court took an unusual approach to settling this dispute, it also adopted important stances on a number of complex issues of sustainable development and delicate problems of ‘general’ international law. It significantly contributed to the elucidation and consolidation of many rules pertaining to the law of treaties, the law of international responsibility, and their mutual relationship. The Gabčíkovo-Nagymaros Judgment and its Contribution to the Development of International Law offers a comprehensive analysis of both the management of this case and the substantive legal issues at stake. It also reappraises the Court’s findings in light of subsequent developments in the international legal order, focusing on the role of the ‘World Court’ in fostering such developments.