This book provides a path-breaking socio-historical account of the global transformation of international criminal law (ICL) through the engagement of justice activists and national courts in Latin America and Central Eastern Europe (CEE). Based on ethnographic observation, analyses of jurisprudence, and interviews with lawyers and judicial officials from Argentina, Brazil, Bulgaria, Estonia, Guatemala, Lithuania, Paraguay, and Romania, it demonstrates how judges, prosecutors, and human rights campaigners constructed novel and counter-hegemonic readings of ICL to fight impunity and realize justice for gross human rights violations after the fall of the military and communist dictatorships at the end of the 1980s. These reinterpretations were fundamentally shaped by the legal education and specific visions about the relationship between law and politics of particular legal actors and organizations, including their quest to establish particular historical narratives about the dictatorial past and question an international order that peripheralized the political violence that had unfolded in Latin America and CEE during the Cold War. Rather than a set of neutrally constructed doctrines, rules, and procedures, this book helps to reveal how the law is enacted, fashioned, and refashioned at the intersection of history, politics, and the subjective attitudes of the legal actors towards the social world.