Summary

While the post-1945 period witnessed the rise of multilateralism and the creation of numerous international institutions to deal with cross-border issues, the 21st century is marked by their contestation and transformation. The United Nations, including its specialized agencies and several other bodies, has come under heavy criticism for the inability to effectively cope with global challenges. In this context, a wide array and diversity of new international institutions have been established by both state and non-state actors—some as complementary and others as alternatives to the United Nations system. These have different positions of power, interests, and motivations for addressing transboundary problems and operate in various domains of global affairs. Examples include clubs of like-minded governments tackling transboundary issues outside the United Nations, private certification initiatives aiming to set standards for responsible corporate behavior and practices, or multi-stakeholder partnerships spanning parties from different societal sectors that jointly work on specific policy problems. Such developments have led to an ever-growing degree of institutional complexity at the global level, which is the subject of intense debates among scholars of international relations. In general terms, complexity here alludes to the systemic, nonlinear, and dynamic relationships between institutions, which are interconnected via multiple flows within a network and exhibit some degree of legal and/or functional overlap. The increase in institutional complexity makes it difficult for all actors to navigate and develop adequate responses to transboundary problems—hence bearing crucial implications for the governance of interdependent policy areas. Yet it remains an open question whether the abundance of international institutions operating in world politics may lead to dead-ends in global policymaking in the short term or will open new opportunities for global cooperation and multilateral collaboration in the medium to long term.