See this important article, here, by one of the great military historians, John Keegan, expressing grave reservations and dissatisfaction with the International Criminal Court and similar civilian justice mechanisms, over what he calls the "rough justice" of traditional military court martial system of dealing with war crimes. Thanks to Opinio Juris for the link.
"There is now an International Criminal Court at the Hague, set up to try to punish war criminals. The law of war crimes has been incorporated into British law under the International Criminal Court Act of 1991 ... The United States has been much denounced for failing to fall into line with other states, particularly in Europe. Recent events suggest, however, that the Americans may have been wise to withhold their consent. The British are discovering why."