‘Relevant Rules’ as Normative Environment - Harmony vs Cacophony in the ITLOS Advisory Opinion on Climate Change

Abstract

On 21 May 2024, the International Tribunal for the Law of the Sea (ITLOS) delivered its much anticipated Advisory Opinion on Climate Change. This post zeroes in on one particular interpretative issue, and its wider ramifications for the development of international law, namely the Tribunal’s approach to Article 31(3)(c) of the Vienna Convention on the Law of Treaties (VCLT) (which enshrines the principle of systemic integration) in connection with the interpretation of UNCLOS. Although ITLOS did not elaborate in detail on its approach, as can be seen from its entire analysis, the Tribunal has demonstrated a clear and principled choice with respect to the content and application of Article 31(3)(c) VCLT and its customary counterpart.

Keywords

• Climate Crisis
• ITLOS
• Paris Agreement
• UNCLOS
• Vienna Convention