This book examines how national and international regional courts in Europe and Latin America address justice for serious human rights violations, comparing approaches across these distinct regions. It analyzes judicial responses to gross violations of international human rights law and humanitarian law—including genocide, crimes against humanity, and war crimes—through the lens of regional institutional frameworks. The comparative analysis explores decades of significant case law addressing atrocities such as murder, torture, sexual offenses, and enforced disappearances in both conflict and peacetime settings. The book contrasts Europe’s experience with mass atrocities during the World Wars, Balkan conflicts of the 1990s, and recent violations in the Caucasus and Ukraine, against Latin America’s widespread abuses under dictatorial regimes and internal armed conflicts in countries like Argentina, Brazil, Chile, Colombia, Guatemala, and Peru during the latter decades of the 20th century. This volume is essential reading for legal scholars, human rights practitioners, judges, prosecutors, defense attorneys, and policymakers working in international criminal justice. It also serves as a valuable resource for graduate students and researchers in law, political science, international relations, and peace and conflict studies who focus on accountability mechanisms for serious human rights violations across different regional contexts. The chapters in this book were originally published as a special issue of The International Journal of Human Rights.