Diffusion of environmental treaty dynamism: EU and US influences

Abstract Multilateral environmental agreements (MEAs) can be dynamic in that they evolve with the introduction and adaptation of new legal commitments. This research contributes to explaining such treaty dynamism by exploring its diffusion across institutions. I focus on the role of the European Union (EU) and the United States (US) in the broader network of MEAs, eventually contending that dynamism diffuses more strongly through EU inter-agreement ties. The US inter-treaty network, however, is likely to play a limited role in facilitating the diffusion of new commitments. It is argued that these patterns are plausibly driven by the EU’s consistently pro-environmental agenda and its economic interests geared toward regulatory norm harmonization across MEAs. The empirical evidence is based on spatial models analyzing the most comprehensive data set of MEAs concluded since 1945. The results show that EU linkages promote treaty dynamism, whereas US ties have no significant effect on dynamism diffusion.