Eric Posner on the Legal (and Political) Constraints on the President's War-Making Powers
The United States is now officially at war with the Islamic State in Iraq and Syria. U.S. planes began dropping bombs on targets in Syria this week. Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, has told the Senate that ground troops may be needed. But President Obama did not ask Congress for legal authority to go to war. Bruce Ackerman, a professor at Yale Law School, thundered in the New York Times that Obama’s declaration of war “marks a decisive break in the American constitutional tradition,” reflecting the theories underlying “Bush-era abuses of executive authority.” Many other commentators agreed that Obama’s act was unlawful. But it’s not. The “Bush-era abuses of executive authority” reflected constitutional traditions that Obama now takes advantage of.
To judge the legality of war against ISIS, the terrorist group that calls itself the Islamic State, we need to be clear about two issues. The first is whether the president can put troops in harm’s way on his own authority. While the Constitution vests in Congress the power to “declare war,” presidents have launched military attacks on their own for many decades. Obama used military force in Libya in 2011; Bill Clinton, in Serbia in 1999; George H.W. Bush, in Panama in 1989; and Ronald Reagan, in Grenada in 1983. In all these cases, and many more (including the Korean War), Congress did not give its consent. Executive branch lawyers have ginned up an “implicit” constitutional authority to use force on one’s own—located variously in the commander-in-chief clause of Article II of the Constitution, or in the general grant of “executive power” to the president, which has been claimed to include at least limited war powers.
The second is whether unilateral force violates the War Powers Resolution, a 1973 law that Congress passed to try to rein in unilateral warfare by the president. That law provides that if the president sends troops into hostilities, he must withdraw them within 60 days unless he obtains consent from Congress. The statute obviously is in tension with the theory that the executive can use force on his own, and its constitutional status has been disputed.