Regional Intergovernmental Organizations as Catalysts for Transnational Policy Diffusion: The Case of UNASUR Health

Why do member states of regional intergovernmental organizations (RIOs) voluntarily adapt their policies and institutions to the norms and procedures implemented in other member states? I tackle this puzzle by investigating the domestic effects of health cooperation among South American states within the Union of South American Nations (UNASUR). The article shows how the establishment of a regional sector-based institution like the Health Council of UNASUR triggered the diffusion of similar policies by reducing transaction costs and increasing information exchanges among member states' health bureaucracies. I argue that RIOs such as UNASUR catalyse transnational diffusion not by enforcing binding regional norms (as in the case of the EU), but by bridging member states' shared functional needs and asymmetric capacities in specific policy areas. Using the case of UNASUR Health, the article contributes to the study of the logics of transnational diffusion within RIOs in the absence of authority delegated to supranational institutions.