Abstract: What are the President's war-making powers? This essay, a brief reply to an article by Curtis Bradley and Jack Goldsmith, contends that the answer lies in administrative law, at least in the first instance. The President's authority often depends on what Congress has said, and under established principles, the President has a great deal of power to interpret ambiguities in congressional enactments - in war no less than in peace. The principal qualifications involve interpretive principles, also found in administrative law, that call for a narrow construction of presidential authority to invade constitutionally sensitive interests. The relevant arguments are illustrated throughout with reference to the 2001 authorization for the use of military force in response to the attacks of September 11; the authorization may or may not include the power to make war on Iraq and Afghanistan, to use force against those suspected of giving financial aid to terrorist organizations, and to detain American citizens.