The jurisdiction ratione materiae of an international court or tribunal in a particular dispute settlement system relies on a sensitive balance between the safeguard of the consensual basis of jurisdiction and the need for the effective settlement of international disputes. Thus, the scope of the jurisdiction ratione materiae of an international court or tribunal constitutes a crucial issue in international adjudication. This issue was vividly raised in the 2020 Enrica Lexie Incident arbitration between Italy and India. In this case, the arbitral tribunal constituted in accordance with Annex VII to the UN Convention on the Law of the Sea held that it had jurisdiction to decide the issue of immunity that necessarily arose as an incidental question in the application of the Convention. However, the validity of the Tribunal’s approach needs careful consideration. Therefore, this article critically examines the Arbitral Tribunal’s approach in the Enrica Lexie Incident arbitral award.