After nearly four years of failing to provide meaningful oversight of the Iraq war, it is no wonder that the newly Democratic Congress is eager to make up for lost time. Congressional proposals for reversing the course of the war are flying fast and furious. They include Sen. Barack Obama's call for a drawdown by May 2007 and a complete withdrawal by the end of March 2008, and various suggestions to amend the original authorization for the Iraq war to limit the troops to peacekeeping and fighting al-Qaida.
Given the Bush administration's generally disastrous conduct of the Iraq war and occupation, and its unrivalled claims of unilateral executive war powers, these reassertions of congressional authority are understandable. But are they constitutional? And are they wise?
The Constitution gives Congress the power to declare wars, fund them, and oversee the way they are fought. Yet the Constitution never says exactly how these powers are to be reconciled with the president's authority as commander in chief. The Constitution surely must empower the president to fight wars effectively enough to win them. That means that war must be conducted under the president's direction, not run by committee. In the modern era, no country—not even a parliamentary democracy—has been so foolhardy as to place a war under the guidance of a legislative body, rather than a single, unified command.
Many questions about the constitutional division of powers never make it to court, so we often cannot look to Supreme Court precedent to give us the answers. Historical practice cannot always be translated into practical guidance, since the nature of our government has changed almost as much as the nature of warfare over the last couple of centuries.
We are not totally at sea, however. The most influential modern Supreme Court opinion on separation of powers, Justice Robert Jackson's concurrence in the so-called Steel Seizure case, makes it clear that the realities of the modern world must be considered in tandem with institutional capacities of the different branches. The best approach to the constitutionality of the recent proposals therefore must take account of how modern war is fought. Justice Jackson's insight was that the Constitution must be read to promote the coordination of the expertise of each of the political branches, and to create a measure of constitutional distrust whenever one branch seeks to assume the responsibilities of the other.
The short answer to the question of institutional competence is that Congress is good at expressing the popular will about whether we should be at war or not, and what kind of a war it should be, while the president is good at actually fighting the war (or at least he should be). The Constitution should therefore be understood to allow Congress to declare and define the nature of the war while guaranteeing the president's authority to make decisions that are crucial to the tactical conduct of it.
In practice, that means Congress can declare that a war must come to an end. Congress can even say the conflict must be over by a specific date, as Sen. Obama has proposed. But once Congress has authorized the president to fight, it has neither the competence nor the authority to tell him which troops should be placed where on the battlefield. Nor can it order him to withdraw particular troops—or particular numbers of troops—by a specified date, as Obama's proposal, among others, would do. Finally, Congress cannot limit the number of troops who may fight.
The tactical essence of war is the decision to place some number of soldiers in a particular place at a particular time. Whoever controls that decision controls the war. To give this power to Congress would be to leave the president without true command authority over his forces and the flexibility needed to respond to military exigencies. For Congress to say how many troops must or must not be in the theater of war at a particular moment would make Congress into the effective commander in chief.