UCLA School of Law

The signature feature of 21st century global governance is arguably not the international regime but the regime complex. A regime complex is an array of partially overlapping and nonhierarchical institutions that includes more than one international agreement or authority. The institutions and agreements may be functional or territorial in nature. International regime complexity refers to political systems of global governance that emerge because of the co-existence of rule density and regime complexes. This review essay highlights insights and questions that emerge from the last fifteen years of scholarship on the politics of international regime complexity, explaining why regime complexes arise, what factors sustain them, and the range of political effects regime complexity creates. Our conclusion explains why in a Post-American world order, the trend of international regime complexity will likely accelerate.