March 21, 2011

PRESIDENT OBAMA went to some lengths to get United Nations authorization and Arab League support for the current U.S. mission in Libya . But aside from some last-minute consultations, the president did far less to ensure the support of Congress. This strikes some members of that body, from both parties, as the opposite of what the Constitution requires. They are quoting back to Mr. Obama what he told the Boston Globe in 2007 : “The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation. . . . It is always preferable to have the informed consent of Congress prior to any military action.”

To be sure, when it comes to committing U.S. forces to battle, it would be wrong to substitute the will of the U.N. Security Council, much less the Arab League, for the will of Congress. The framers of the Constitution gave Congress the power to declare war and raise armies precisely because they did not want an unchecked executive committing the country to battle as he pleased; and they wanted clear national political support for those military undertakings that proved unavoidable.

Still, Mr. Obama’s actions of the past week square with his words of four years ago and, more important, with the Constitution — for reasons the president himself has articulated. There is a broad category of military operations short of full-scale war — from hostage rescues to humanitarian relief to enforcement of no-fly zones. Such contingencies, especially when they are likely to remain brief and involve little or no risk to U.S. troops, do not require full-blown debate in Congress and a declaration of war, in part because the process might go on longer than the emergency.

Though not articulated in constitutional text, this principle has been confirmed by many years of historical practice, in which presidents have ordered forces into action abroad without prior congressional authorization. And it is why President Obama did not need a vote of Congress for what he promises will be a short and limited operation, soon to be handed over mostly to other nations, whose initial aim was to block Moammar Gaddafi’s forces from sacking opposition-controlled Benghazi.

Things could change, however, if the operation mutates into something longer and more ambitious — as wars are wont to do. In that regard, Mr. Obama has done himself no favors by saying that the goal for which he is using force — protecting civilians — is separate from a goal — ousting Mr. Gaddafi — that Mr. Obama also has embraced. On Monday, the president made the required report triggering a 60-day time limit for the use of force in Libya without a vote of Congress. Congress should use that time to demand more clarity about U.S. objectives. And Mr. Obama should welcome the chance to provide it.