Historical Survey of the War Powers and the Use of Force
Under the Constitution, the ultimate authority to control the deployment of military forces lies with Congress. That principle is bedrock to our governmental system. Yet we all know that the conditions of the 20th century, including the availability of a standing army, have shifted much of that power to the President. The war-making power of the President constantly erodes the war-declaring power of Congress. Nevertheless, the contemporary growth of presidential power does not take from Congress any of its original powers--powers which may at any time place limits on the extent to which the President can deploy armed forces.
Congressional acquiescence, of course, expands the scope of presidential power and may invite additional executive encroachments. It is tempting to suggest that presidential initiatives may be tolerable for short-term military commitments, but that long-term involvements require congressional approval. To some extent the historical record supports that dichotomy, but much depends on the nature of the action and its location. For example, given the explosive conditions of the Middle East, it was important for President Bush to obtain congressional approval before going to war against Iraq, regardless of the war's duration.
The framers were quite deliberate about placing with Congress the fundamental power to deploy armed forces. Had they wanted to vest that control with the President, they had many models to choose from. John Locke, in his Second Treatise of Government, delegated foreign policy (the "federative" power) to the Executive. The federative power consisted of "the power of war and peace, leagues and alliances, and all the transactions with all persons and communities without the commonwealth." To Locke, the federative power was "almost always united" with the Executive. Any attempt to separate that power from the Executive would invite "disorder and ruin."1