In the 2023 judgment of Nicaragua v. Colombia, the International Court of Justice ruled that, under customary international law, a State’s entitlement to a continental shelf beyond 200 nautical miles from its baselines is not permitted to extend within 200 nautical miles from the baselines of another State. In identifying this customary rule, the Court did not apply the two-element approach. The state practice relied upon by the Court to identify the general practice is not sufficiently widespread, representative, or consistent. The opinio juris is inferred from such state practice, which is not necessarily driven by a sense of legal obligation. The Court’s assertion of the customary rule constitutes, in effect, a rewriting of the relevant provisions of the United Nations Convention on the Law of the Sea, amounting to a legislative exercise.

While the law of State responsibility, particularly the principle of full reparation, provides general guidance for achieving full reparation, it is not quite obvious what kinds of reparation qualify as “full” and how to actualize full reparation. This article centres on the principles, approaches and methods surrounding full reparation for armed conflict-related environmental damage in the law of State responsibility. It examines how the environment is legally defined as an object of protection under international law, and discusses practical challenges in international compensation for wartime environmental damage. In doing so, it ascertains the underlying objective of full reparation, develops an approach to assessing wartime environmental damage, and draws on experiences of international jurisprudence to quantify compensation for wartime environmental damage.