In the first 219 years of our existence, the United States fought in numerous wars against foreign powers, taking roughly five million prisoners. Some were held only very briefly; others were executed as war criminals. Between these opposite ends of the spectrum, most were detained for some period of weeks, months, or years. There was one common feature in all this variant treatment: It was exclusively controlled by the executive branch of the federal government. Whether the question for consideration was which enemy operatives should be captured, which should be interrogated (and how), or which should be released, decisions were made by the government officials constitutionally responsible for the conduct of warfare, meaning, almost all of the time, by military commanders. More fundamentally, it was understood to be for them, the commanders, to decide who was the enemy—i.e., to sort out combatants from civilians. It was for the commanders to determine the parameters of the battlefield. And the compass guiding all of the relevant decision-making was military necessity. The law was thought to have little or no bearing at all.

This did not mean there were no protocols in place. Far from it. The laws and customs of war are centuries old—much older, in fact, than the United States. Nevertheless, it was understood that the existence of such protocols—better thought of as guidelines or rules of reason than laws—was not tantamount to control by courts. Still less did the existence of protocols entail the subservience of all