"Particularly when the war power is invoked to do things to the liberties of people, or to their property or economy that only indirectly affect conduct of the war and do not relate to the engagement of the war itself, the constitutional basis should be scrutinized with care. ... I would not be willing to hold that war powers may be indefinitely prolonged merely by keeping legally alive a state of war that had in fact ended. I cannot accept the argument that war powers last as long as the effects and consequences of war for if so they are permanent -- as permanent as the war debts."