Do partisan preferences influence countries’ decisions whether or not to ratify international treaties? And if they do, whose preferences are reflected in ratification decisions? The present paper explores competing answers to these questions. For this purpose, it compares the explanatory power of several established theories of governmental and partisan policy choices such as the coalition compromise, the median voter and the veto player theory. The analysis is based on the ratification behaviour of 21 OECD countries in two important regulatory areas: environmental protection and labour markets. A new dataset is used combining information on the ratification of more than 200 international treaties with the partisan composition of national governments and institutions. The paper contributes to the debate on comparative theory testing and has important implications for the study of democratic representation and the origins of international commitments.
