Regime Congruence: Rethinking the Scope of State Responsibility for Transboundary Environmental Harm

The advent of the Anthropocene has extended the reach of environmental harm: from offshore drilling to geoengineering and climate change, activities in one State can increasingly injure people far beyond its borders. States have longstanding rights under customary and international environmental law (IEL) to protect their citizens from such harms. In practice, however, States rarely take action against their sovereign peers, seemingly leaving individual victims without a remedy. This need not be the end of the story. As this Article shows, environmental norms interact with and can find expression through other legal regimes. Focusing on the Inter-American human rights system, of which the United States is a member, this Article asks whether, and to what extent, the obligations that IEL imposes on States vis-a-vis each other should shape the content of duties that States owe under human rights treaties to individual rights-holders beyond their jurisdiction. This issue remains under-analyzed in the literature and under-developed in the jurisprudence. This Article seeks to fill those gaps. It represents the first attempt of its kind to develop a theory of regime congruence and apply it to transboundary environmental harm. Its contributions are threefold. First, it develops an analytical framework to examine the scope of State obligations arising at the “nexus” of two mutually-supportive legal regimes — what I call “regime congruence.” In so doing, it points the way toward a more unified conception of State responsibility and contributes to the literature on the fragmentation of international law. Second, it furthers our understanding of the scope of extraterritorial obligations in international law through exhaustive doctrinal analysis and extends the doctrine to the area of transboundary environmental harm, which is in urgent need of clarification. Finally, it re-conceptualizes the notions of enforcement in IEL by showing that a congruent regime can actually provide more effective remedies to individual victims than IEL itself. The argument developed in this Article has significant implications for access to justice and accountability in the Western Hemisphere. It suggests not only that the United States could incur international responsibility for domestic acts or omissions that cause transboundary harm, but also that individual U.S. residents would be entitled to direct recourse against neighboring States in the Inter-American system whose failure to control domestic pollution violates their rights.