The effects of treaties on human rights performance may depend in part on how domestic legal systems articulate with international law. The idea motivating this study is that constitutional law can make a difference not necessarily by including rights but by acknowledging and connecting to treaty law. This study is a first attempt to explore the interrelated effects of treaties, constitutions, and courts on human rights performance.The key proposition is that human rights treaties may have a greater influence on rights in countries whose constitutions incorporate treaty law and whose courts are independent of the political branches of government. The analysis tests that proposition using data from about 150 countries across 20 or more years. The results offer evidence that treaties, constitutions, and courts do combine, at times, to improve human rights performance, with judicial independence playing the key role.With the proliferation of human rights treaties after World War II, activists, scholars, and citizens have held the hope that international law could help to protect human rights and reduce abuses. Treaties to protect rights could empower victims and their advocates provide tools to nongovernmental organizations, strengthen elements of the state that oppose abuses and influence legislative agendas. The hope has been that international human rights law could improve human rights, at least on the margin and perhaps more fundamentally over the long term.Research on the effects of treaties on human rights performance has not been encouraging. Early studies reached pessimistic conclusions, with more recent research finding limited positive effects of treaty participation on human rights performance in some contexts. Scholarship on the effects of constitutional provisions on human rights practices has been perhaps even less encouraging. Rights provisions are a virtually universal feature of modern constitutions, even in countries where governments routinely violate human rights.This article begins with the idea that the effects of treaties on human rights performance may depend in part on how domestic legal systems articulate with international law. Legal protections for human rights may be mutually reinforcing, so that human rights law is more effective when it links across legal levels-national and international-and with domestic legal institutions. The intuition is that constitutional law can make a difference not necessarily by including rights-almost all constitutions do-but by acknowledging Wayne Sandholtz is Professor of Political Science at the University of California, Irvine. Much of his research has focused on the development, diffusion, and effects of international norms. His most recent books (Prohibiting Plunder and International Norms and Cycles of Change) offer a framework for explaining how and why norms change and apply it to a variety of substantive domains. His current research focuses on the role of national high courts in the transnational migration of legal ideas and principles.