Obama Already Has Authority to Fight Islamic State

The 2001 Authorization for Use of Military Force gives President Obama all the authority he needs to fight Islamic State.
Iraqi forces and Peshmergas are seen following clashes with Islamic State fighters earlier this month.

Does the Barack Obama administration have the legal authority to use military force against Islamic State? Some constitutional scholars, and some members of Congress, have been skeptical, even dismissive. But as a matter of law, the president has a strong justification. (Disclosure: My wife, Samantha Power, is the U.S. ambassador to the United Nations and hence one of the president's national security advisers.)

In 2001, Congress gave the George W. Bush administration broad authorization to respond to the Sept. 11 attacks. The Authorization for Use of Military Force explicitly says the president can "use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided" the 9/11 attacks, or even that "harbored such organizations or persons." For present purposes, the most important word here is "organizations," and the key phrase is "he determines."

No one doubts that the AUMF authorizes the president to fight people who have joined al-Qaeda. It's also clear that the president can use force against any group that links itself to al-Qaeda, at least if it can be considered part of the same "organization." At the same time, the AUMF does not give the president roving authority to strike against any terrorist organization. It establishes a clear predicate: a relationship to the 9/11 attacks.

In light of Islamic State's close working relationship with al-Qaeda, the president could "determine" that it was essentially part of the group in 2004 and for a significant period thereafter. Indeed, Islamic State has often been described as "al-Qaeda in Iraq," and it has reportedly been subject to al-Qaeda's direction and control.

Last February, however, al-Qaeda publicly dissociated itself from Islamic State, partly because of Islamic State's brutality, including beheadings. So now the question is: Does this mean that Islamic State can no longer be treated as part of an "organization" responsible for the attacks of 9/11, such that the president cannot act (in the words of the AUMF) "to prevent any future acts of international terrorism against the United States"?

Skeptics may think so, but it's hard to see why. Imagine that in 2012, al-Qaeda split into two organizations: the original one and a new, more brutal group with a new name. Under the AUMF, the president would plainly have the authority to use force against both.

True, the Islamic State situation is not precisely the same, because it has always had its own name and identity. But if it was part of al-Qaeda for a significant period, it's not easy to argue that al-Qaeda's announcement of dissociation last February (for excessive brutality, no less) suddenly deprives the president of the authority he had in January. Keep in mind that the group insists it is the true inheritor of the legacy of Osama bin Laden.

Of course, it might be desirable, both domestically and internationally, for Congress to give Obama explicit support for attacking Islamic State. But he has a strong argument that, as a matter of law, 2001's AUMF already gives him the requisite authority.

This is to say nothing of what some people consider to be the president's independent power to protect citizens of the U.S. from potential kidnappings, beheadings and bombings. Consider this unambiguous statement: "The President has authority under the Constitution to take action to deter and prevent acts of international terrorism against the United States."

These are not the words of President Bush or Vice President Dick Cheney, or of President Obama. They come from the 2001 AUMF -- passed in the House by a vote of 420-1 and in the Senate unanimously.

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