While a number of different theoretical models have been advanced to explain why states implement—or, indeed, do not implement—multilateral environmental agreements (MEAs), very little empirical work has been undertaken to validate their predictions. With a view to narrowing this gap, the present article adopts a large-N, econometric approach to test the explanatory power of four distinct models of compliance—domestic adjustment, reputational, constructivist and managerial—in the context of European Union (EU) environmental policy. Using data on the number of ofıcial infringements received by 15 member states for non-implementation of environmental directives over the period 1979–2000, we ınd that all four models make a statistically signiıcant contribution to explaining spatio-temporal differences in legal implementation. Thus, our results suggest that the implementation of MEAs is shaped by a combination of rational calculations of domestic compliance costs and reputational damage, domestically institutionalized normative obligations, and legal and political constraints. We conclude by suggesting a greater need for multi-causal theoretical models of supranational legal compliance.

This article argues that the WTO's past environmental record is much better than critics would have it. Its jurisprudence has become increasingly environmentally friendly and many charges against the dispute settlement process are based on misunderstandings. WTO rules have, so far at least, not deterred any multilateral environmental agreements. The lack of ambitious environmental protection measures is not the fault of the WTO, but the responsibility of policy-makers from its member states. At the same time, the WTO has done little to actually promote environmental protection and the treatment of the precautionary principle in WTO rules is highly unsatisfactory. Unfortunately, this is unlikely to change in the future. The reason for this is that there is not enough support among member countries, particularly those from the developing world, to render the multilateral trade regime more environmentally friendly. The challenge is to green WTO rules in a way that is beneficial and therefore acceptable to developing countries.

Economic theorists of international environmental cooperation and regime theorists who focus on the environment ask the same two basic research questions: why does international environmental cooperation emerge in some cases, but not in others, and why is cooperation wide and deep in some cases, but not in others? Unfortunately, the two schools of thought do not collaborate much in their respective attempts to answer these and related questions. Instead, mutual neglect is the general rule. This paper explores how regime theory can learn from the findings of the economic theory of international environmental cooperation and vice versa, and it examines the prospects for reciprocal learning. An exploitation of mutual learning opportunities is likely to lead to a more comprehensive understanding of international environmental cooperation, and it can ultimately result in better policy advice.