Article I, Section 8, Clause 11 of the U.S. Constitution grants Congress the power to declare war. The President, meanwhile, derives the power to direct the military at all times, whether or not there is a formal declaration of war, from Article II, Section 2, which names the President Commander-in-Chief of the armed forces. The President’s constitutional powers are quite broad in the context of limited military action. Additionally, courts have long upheld the President’s right to be the sole voice of the nation, in charge of conducting our foreign policy. In general, constitutional powers are not so much separated as "linked and sequenced"; Congress's control over the armed forces is structured by appropriation and provision, while the President commands all military forces.
The War Powers Act, which Congress designed to limit a President’s power to commit U.S. troops to combat, was passed as a Joint Resolution in 1973. The Act concedes that the commander-in-chief role gives the President power to repel attacks against the United States and makes the President responsible for leading the armed forces. It provides that the President can send the armed forces into action abroad only by declaration of war by Congress, "statutory authorization," or in case of "a national emergency created by attack upon the United States, its territories or possessions, or its armed forces.” It also requires the President to notify Congress within 48 hours of committing armed forces to military action and forbids armed forces from remaining for more than 60 days, with a further 30-day withdrawal period, without a Congressional authorization for use of military force (AUMF) or a declaration of war. It must be noted, though, that no Administration of either political party has agreed that the War Powers Act is constitutional. Instead, rather than formally “complying with” the provisions of the Act (which would imply agreement with the Act’s legality), all Administrations state instead that they are acting “consistent with” the Act’s provisions (which implies that they are acting as they do because they freely choose to do so, not because they are compelled to do so).
