While torture is never, under any circumstances, permitted by law, targeted killing sometimes can be. The question—and it’s a big one—is when.

The DOJ white paper doesn’t succeed in answering the question. …

To say when targeted killing is legal, the white paper would have to do two things. It would have to identify a source of authority in the U.S. Constitution, or in laws passed by Congress, that gives the president the power to use force. And it would have to identify and apply the U.S. and international laws that limit when such force can be used.

Start with the source of authority. The white paper says that the president has some power to use force as part of his “constitutional responsibility to defend the nation.” Indeed, the Supreme Court has recognized that Article II of the Constitution gives the President at least some authority to, as the framers put it, “repel sudden attacks,” without having to go to Congress first for permission—in other words, to play defense in the moment. It’s not hard to imagine an argument that the government targeted U.S. citizen Anwar al Awlaki in Yemen because of a discovery that he was about to launch a particular, sudden attack. But the paper doesn’t actually make that argument. It’s not just that al Awlaki goes unmentioned. So does Article II. And true enough, the administration has been at pains, in court challenges to its detention power at Guantanamo, to avoid resting its claim of authority on the president’s constitutional power alone—precisely because such claims of authority can be overly broad.