Hard and Soft Commitments to Human Rights Treaties, 1966–20001

What factors determine whether and how deeply countries will commit to the international human rights regime? Using data for up to 142 countries between 1966 and 2000, this article analyzes patterns of membership to the International Human Rights Covenants. The analysis produced two main conclusions. First, the potential costs associated with joining a treaty, rather than its substantive content, motivates the decision to join. Treaties that protect different rights but establish comparable implementation mechanisms exhibit similar patterns of membership, whereas treaties that protect identical rights but establish different implementation provisions exhibit dissimilar patterns of membership. Second, rates of treaty membership differ by level of commitment. Countries that sign human rights treaties differ from countries that ratify. Results are interpreted with respect to four theories of commitment and compliance: realism, liberalism, constructivism, and sociological institutionalism. Theories that emphasize the importance of a treaty’s costs (realism and institutionalism) fare better than theories that prioritize a treaty’s content (liberalism and constructivism).