In his chapter on "War Crimes" taken from his book Nuremberg and Vietnam:An American Tragedy, the American chief prosecutor at Nuremberg, General Telford Taylor, provides a usefully brief history of the "laws of war." From largely unwritten rules of conduct, to treaties, military manuals, and decisions of military courts, such "laws" remain substantially a body of laws based on custom, growing much as the common law of England grew in preparliamentary times. Taylor also helps us understand the reasons for the amorphous and shifting quality of the laws of war, and the relevance and constraints of what goes under the designation "military necessity."
What is a "war crime"? To say that it is a violation of the laws of war is true, but not very meaningful.
War consists largely of acts that would be criminal if performed in time of peace—killing, wounding, kidnapping, destroying or carrying off other peoples' property. Such conduct is not regarded as criminal if it takes place in the course of war, because the state of war lays a blanket of immunity over the warriors. This concept is very ancient; it is clearly stated by the 12th century compiler of canon law, Gratian: "The soldier who kills a man in obedience to authority is not guilty of murder."
But the area of immunity is not unlimited, and its boundaries are marked by the laws of war. Unless the conduct in question falls within those boundaries, it does not lose the criminal character it
From Nuremberg and Vietnam:An American Tragedy by Telford Taylor. Copyright 1970 by the New York Times Book Company. Reprinted by permission of Times Books, a division of Random House, Inc.