This book offers a unique study of the law of command or superior responsibility under international law. Born in the aftermath of the Second World War, the doctrine of superior responsibility provides that a military commander, a civilian leader, or the leader of a terrorist, paramilitary, or rebel group could be held criminally responsible in relation to crimes committed by subordinates even where he has taken no direct or personal part in the commission of these crimes. The basis of this type of liability lies in a grave and culpable failure on the part of the superior to fulfil his duties to prevent or punish crimes of subordinates. The idea that a superior could be held criminally responsible in relation to crimes of subordinates is central to the ability of international law to ensure compliance with standards of humanitarian law, and it remains a most important legal instrument in the fight against impunity. Though it first developed in the international arena, the doctrine of superior responsibility has now spread into many domestic jurisdictions, thus offering judicial and prosecutorial authorities a ready-made instrument to hold to account the leaders of men who knew of the crimes of their subordinates but failed to adequately respond to prevent or punish those crimes. This volume provides a comprehensive and insightful dissection of the doctrine of superior responsibility and the scope of its application, as well as the evidential difficulties involved in establishing the criminal responsibility of a superior in the context of a criminal prosecution.