Hierarchy and differentiation in international regime complexes: a theoretical framework for comparative research

The concept of international regime complexity offers a useful lens for examining the increasing density of international institutions in global governance. A growing literature in International Political Economy (IPE) identifies clusters of overlapping institutions in many important policy areas, yet some scholars argue that complexity undermines governance effectiveness, while others perceive distinct advantages over unified institutions. To bring coherence to these findings, we present a general theoretical framework that characterizes regime complexes based on two structural features: Authority relations and institutional differentiation. These dimensions jointly determine the opportunities and constraints that states and other actors confront as they navigate institutional rules. As a result, they shape important outcomes, such as policy adjustment, regime shifting and competitive regime creation. The article proposes testable hypotheses regarding the effects of authority and differentiation, and we assess their correspondence with the eight regime complexes examined by the five companion articles in this special issue. We further identify a set of dynamic processes that shape the evolution of regime complexes over time. Our framework strengthens the foundation for comparative analysis of regime complexes and charts a new agenda for the research program.