War Crimes

"It is an easy thing to condemn one man in the dark. It is easy to condemn the German people to speak of the basic flaw in the German character that allowed Hitler to rise to power and at the same time positively ignore the basic flaw of character that made the Russians sign pacts with him, Winston Churchill praise him, American industrialists profit by him. Ernst Janning said he is guilty. If he is, Ernst Janning's guilt is the world's guilt--no more, no less."
--Hans Rolfe (Judgment at Nuremberg)

Judge Nap discusses the legitimacy of war crimes and associated prosecution. War crimes are prosecuted by the victors. They control the judicial apparatus which is slanted in manners that insulates victors from prosecution.

Using the post WWII Nuremberg trials as an example, war criminals are generally alleged to have violated unwritten laws--laws which are conveniently concocted for the purpose at hand. This is illegal in the US and in many other countries.

War tribunals seek legitimacy by claiming that they can rightly prosecute war behavior that is so heinous and obvious that the broken laws need not be codified.

However, the only 'obvious' uncodified law is natural law. Natural law is grounded in the non-aggression principle. The non-aggression principle posits that all aggression is wrong and violates the natural rights of the victim. 

This means that only defensive behavior in war is just. People or countries can defend themselves from invaders, but by using only the violence necessary to neutralize the threat. Pre-emption, or counter offensives violate the non-aggression principle.

In reality, of course, few wars involve one side acting purely in self-defense. The original defender commonly turns around and mounts offensives against the original invader, thereby reverse the roles.

Viewed from this perspective, many war crimes are committed during armed conflict and are perpetrated by people on all sides--even by those not firing shots.

Obviously, that's not how war crime tribunals typically proceed. Instead, war crimes constitute what's in the eyes of the beholder.