Binyam Mohammed, who planned terrorist attacks on U.S. cities, has been set free. Let’s imagine we’ve captured a highly trained terrorist al-Qaeda was attempting to embed in the United States, à la Mohamed Atta and company, to carry out mass-murder attacks in American cities. For eight years, our national-security debate in the United States has been divided into two camps on these cases. In the first are those who accept the post-9/11 law-of-war paradigm. They would have that enemy combatant detained for intelligence purposes (and to remove him from the battlefield) until he could be tried for war crimes by...