In the fifteen years since the Authorization for Use of Military Force (AUMF) was enacted on September 18, 2001, the Taliban has been removed from power but not eliminated; Osama Bin Laden has been killed and the senior leaders of Al Qaeda as of 9/11 have been captured, killed, or driven underground, although Al Qaeda remains a threat; numerous Al Qaeda affiliates have sprung up around the globe, most notably in Iraq, Yemen, Syria, and Somalia; and most ominously, the Islamic State has arisen from the ashes of Al Qaeda in Iraq to become what the Director of National Intelligence has described as “the preeminent terrorist threat” against the United States “because of its self-described caliphate in Syria and Iraq, its branches and emerging branches in other countries, and its increasing ability to direct and inspire attacks against a wide range of targets around the world.”
Despite massive changes in the geographical scope of the conflict that began on 9/11, the strategy and tactics employed, and the identity of the enemy, the AUMF remains the principal legal foundation under U.S. domestic law for the president to use force against and detain members of terrorist organizations. The AUMF is already the longest operative congressional authorization of military force in U.S. history, and, as of fall 2016, there was no immediate prospect that Congress would move to repeal or update it. With the continued vibrancy of Al Qaeda, its associates, and the Taliban, and with the 2014 presidential extension of the AUMF to cover military operations against the Islamic State, the AUMF is likely to be the primary legal basis for American uses of force for the foreseeable future.