The aim of this book is to examine problems of accountability for genocide and crimes against humanity committed by non-state actors such as individuals, armed groups (rebels, insurgents, belligerents, national liberation movements, rebel groups, armed opposition groups, unrecognized insurgents, parties to an internal armed conflict, successful insurrectional and other movements) and corporations and to analyze content of legal responses available under two branches of international law: human rights law and criminal law. In this context, it will also take a look at the practice of European Court of Human Rights and Inter-American system.