A regime complex is an array of overlapping international institutions and agreements that interact to govern in a particular issue area of international relations. International regime complexity refers to the international political dynamics that emerge from the interaction among multiple overlapping institutions within regime complexes. Scholars have identified several factors explaining the emergence of regime complexes and the growing regime complexity in world politics. Some have emphasized the functional rationale for creating institutional linkages to contain negative spillovers across regimes. Others have focused instead on actors’ incentives, pointing to the various expected benefits of governing through regime complexes rather than through separate comprehensive institutions.
Scholars have also disagreed about the consequences of regime complexes and, in particular, about the extent to which regime complexity facilitates or hinders international cooperation. The early literature tended to emphasize how institutional proliferation and fragmentation contributed to regulatory conflicts, thus undermining global governance outcomes. By contrast, other works provide a more nuanced account of the effects of regime overlaps, showing that under certain conditions regime complexity contributes to the effectiveness of cooperation. A rich body of empirical evidence drawn from the study of regime complexes in several issue areas, including environmental, trade, security, migration, and public health governance, suggests that what matters is not the fragmentation and overlaps per se but how they are managed.
The increasing institutional density and overlaps in international politics in the 21st century has generated significant interest among scholars of international relations (IR). The literature on international regime complexity and regime complexes has evolved theoretically and empirically since the beginning of the 12st century. Three main questions have guided and informed theoretical debates and empirical research on regime complexes. First, what are regime complexes and how are they composed? What is meant by international regime complexity? Second, what causes regime complexity and how do regime complexes emerge? And third, what are the effects and consequences of regime complexity?
