The international sources of policy convergence: explaining the spread of environmental policy innovations

How do international processes, actors and institutions contribute to domestic policy change and cross-national policy convergence? Scholars in the fields of international relations and comparative politics have identified a wide array of convergence mechanisms operating at the international or transnational level. In order to categorize this wide array of possible causes of policy convergence, we propose a typology of three broad classes of mechanisms: (1) the co-operative harmonization of domestic practices by means of international legal agreements or supranational law; (2) the coercive imposition of political practices by means of economic, political or even military threat, intervention or conditionality; and (3) the interdependent but uncoordinated diffusion of practices by means of cross-national imitation, emulation or learning. We illustrate and substantiate this claim through the empirical analysis of the international spread of three different kinds of policy innovation: national environmental policy plans and sustainable development strategies, environmental ministries and agencies, and feed-in tariffs and quotas for the promotion of renewable electricity.