Budiansky tells the story of the first use of military commissions by Americans during the Mexican-American War in 1846. General Winfield Scott ordered the use of commissions when his troops occupied Mexico. According to Budiansky,
Jumping to the present, he argues, "It is a measure of how far we have come as a nation — and in values at one time widely held — that military commissions, once seen as a great stride forward for American principles of justice and the rule of law, will now for ever after be associated with the abridgement of rights."
Scott’s motive was equal parts necessity (maintaining public order) and shrewd politics (appealing to the Mexican population to cooperate with his forces). In place of arbitrary and raw power and summary justice at gunpoint, a system of impartial courts gave Mexicans the assurance that they would be treated fairly.
Scott in particular wanted to impress upon the civilians the contrast between American justice and the lawlessness they had endured when the Mexican forces led by Gen. Antonio López de Santa Anna rode through their villages, looting, raping and killing.
By the same token, Scott used military commissions to try — and punish — American soldiers who had committed crimes, including rape and theft, against local citizens. This, too, was not lost on the populace. General Orders No. 20 became the spark that ignited an international revolution in thinking about martial law. It established for the first time the principle that an occupation commander was subject to a higher legal authority, same as civilian government.
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