The Hidden Hands of Justice: NGOs, Human Rights, and International Courts is the first comprehensive analysis of non-governmental organization (NGO) participation at international criminal and human rights courts. Drawing on original data, Heidi Nichols Haddad maps and explains the differences in NGO participatory roles, frequency, and impact at three judicial institutions: the European Court of Human Rights, the Inter-American Human Rights System, and the International Criminal Court. The Hidden Hands of Justice demonstrates that courts can strategically choose to enhance their functionality by allowing NGOs to provide needed information, expertise, and services as well as shame states for non-cooperation. Through participation, NGOs can profoundly shape the character of international human rights justice, but in doing so, may consolidate civil society representation and relinquish their roles as external monitors.