Policy diffusion is a process during which innovative policy ideas are communicated internationally and implemented voluntarily and unilaterally by an increasing number of countries. As a rule, processes of policy diffusion lead to a convergence of national policies. From a governance perspective, it can therefore be argued that policy diffusion constitutes a mode of international policy coordination in its own right. Contrary, however, to the traditional governance modes of hierarchy and negotiation, coordination does not result from cooperative negotiation of common policies and their domestic implementation but rather from a decentralised process in which autonomous states adapt unilaterally to the decisions of other states around them. Against this backdrop, this article explores the determinants of policy diffusion as well as its potential as a new mode of global governance. In a first step, we define the concept of policy diffusion and point out different, sometimes even contradictory, terminologies. In a second step the coordinating effect of diffusion processes is illustrated empirically. We find that the accumulation of individual cases of imitation or learning results in a degree of policy convergence that is comparable to the effects of hierarchical coordination or multilateral negotiation. Based on this finding, the final sections explore whether, how, and by whom diffusion processes can be utilized for an intentional governance at the international level ("governance by diffusion").

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• Political Science - Social Sciences