Could Hitler have pleaded insanity? Can a soldier participating in a massacre claim duress because his superior forced him? In domestic criminal law complete defenses, such as insanity and duress, are relatively common legal concepts. But what is the role of these arguments in international criminal law? Can horrific large-scale crimes, such as genocide and crimes against humanity, ever be excused? This book provides an analysis of cases featuring complete defenses before international criminal courts (IMT, IMTFE, ICTY, ICTR and ICC). The conclusion of the analysis is that international criminal courts recognize most complete defenses in principle. However, they consistently reject them in practice. Courts thus tend to say: "Insanity is available as a complete defense - but not in this case". This conclusion raises questions as to the compatibility between complete defenses and international crimes: When they are never accepted in practice, should such defenses be available at all? The final Part of the book answers this question in the affirmative and provides recommendations on the contents of complete defenses in the field of international criminal justice.