From Fact to Applicable Law: What Role for the International Climate Change Regime in Investor-State Arbitration?

While many investor-state dispute settlement (ISDS) proceedings based on international investment agreements have dealt, directly or incidentally, with environmental issues, state measures relating to the mitigation and adaptation to climate change have been subject to a small number of reported cases. This article demonstrates that there is a significant gap between the number of investor-state disputes having a direct relevance with climate change, on the one hand, and the number of such cases that have actually raised climate change as a material legal or factual issue. In addition, arbitral tribunals faced with disputes related to measures or sectors that are of direct relevance to climate action have, to date, virtually never engaged in any sort of substantial analysis of international climate change treaties and related instruments, rules, or practices. Against this backdrop, this article will explore ways for arbitrators and parties to ISDS proceedings to better consider the climate regime — in particular, the Paris Agreement and instruments arising therefrom — in ISDS proceedings beyond its current limited role as an element of context. While the literature has mostly focused on integrating climate change concerns in ISDS, this article goes further by exploring how states’ international climate obligations could play a greater role in the adjudication of investor-state disputes, including by providing states with a justification for implementing more ambitious regulations as well as tribunals with guidance for interpreting substantive obligations in investment treaties.