Whether Obama has the constitutional authority to enforce a no-fly zone in Libya without congressional approval is not a difficult call. As commander in chief, the president has broad power to commit U.S. forces to combat operations — and presidents have exercised this power throughout our history. There are, of course, a number of constitutional limits on a president’s right to use of force, but Congress’s exclusive power to “declare war” — the focus of so much debate in this area — is far from the most important of these.
In the 18th century, a declaration of war was not always a necessary precursor to the use of force, and the Constitution’s Framers clearly understood this. As a general rule, a declaration was necessary if a state wished to claim the full international-law rights of a belligerent vis-à-vis its enemies and neutral powers, except where the conflict was purely defensive. Moreover, based on general practice among nations in the years leading up to the Constitution’s adoption, whether a declaration of war was necessary in any particular instance depended on a complex set of considerations involving, among other things, the identity of the other belligerent(s), purposes and goals, location, and the type of force (and forces) to be committed.
The Framers reserved the power to declare war to Congress so that only that body would be able to alter the legal regime governing an armed conflict, and to ensure that congressional action would be required before the United States entered major hostilities with one or more other powers. They left the president free to use force in other instances, subject to a number of other checks on his practical ability to involve the nation in armed conflict, including Congress’s authority over the budget and its power to raise and support armies.
The essentially punitive operations now underway against Qaddafi would not have required a declaration of war at the time the Constitution was adopted, and do not require such action today. We discuss this question further in the Washington Post.
— David B. Rivkin Jr. and Lee A. Casey served in the Justice Department under Presidents Ronald Reagan and George H. W. Bush.