The logic of democratic power is put to an empirical test in Chapter 6. Having identified treaties as the best observable source of international rules, this chapter tests the democratic power argument for international rule–based cooperation systematically in the context of international treaty making, which involves three stages – negotiations, commitment, and compliance. This statistical analysis is based on a dataset of seventy–five international treaties adopted between 1945 and 2008 and is complemented with insights from the International Covenant on Civil and Political Rights. The results reveal consistent and robust empirical patterns regarding states’ willingness and ability to cooperate over international treaties, which are generalizable across treaties, issues, and the stages of treaty making. The analysis confirms the centrality of the democratic powers as the chief promoters and adherents of international rules that gradually but inadvertently contribute to the constitutionalization of world politics.

Operating against anarchy rather than hierarchy, international constitutionalization is a highly contested but unintended political process. It is a by–product of international treaty making, which is intended to create fairly specialized rules within issue–specific domains. Approximating the evolutionary pathway, this process nonetheless generates a less unified international constitutional framework than in the national setting. An examination of international constitutional developments (along the five core constitutional elements) reveals that formalization of international rules through treaties has become standard in the post–1945 period. Sovereignty has developed into the fundamental international principle, extending the circle of members to include newly emerging states. Relations among states have deepened to enhance inter–state cooperation, and rights and duties have further reproduced inequalities among states. The chapter concludes by stressing the inadvertent constitutional consequences of international treaty making, which leads to the constitutionalization trap.