U.S. Military Action Against the Islamic State: Answers to Frequently Asked Legal Questions [September 25, 2014] [open pdf - 377KB]
"Ongoing U.S. military operations against the Islamic State (which formerly referred to itself as the Islamic State of Iraq and the Levant, and is also commonly referred to as IS, ISIS, or ISIL) raise issues concerning the allocation of war powers between Congress and the President, including whether such operations have been (or are required to be) authorized by an act of Congress. In August 2014, President Obama ordered U.S. forces to commence airstrikes against IS targets in Iraq to assist the Iraqi government in combating the insurgent force, protect U.S. military and nonmilitary personnel in Iraq, and support certain humanitarian operations. In a public address on September 10, 2014, President Obama announced the pursuit of a strategy to 'degrade and ultimately destroy' the Islamic State, including through the escalation of U.S. airstrikes against IS forces in Iraq, as well as the possible initiation of U.S. airstrikes against IS forces located in neighboring Syria. On September 23, 2014, the United States began airstrikes in Syria targeting IS forces and certain other groups within that country believed to be affiliated with Al Qaeda. As of the date of this report, Congress has not enacted legislation specifically authorizing U.S. force against the Islamic State. In enacting the Continuing Appropriations Resolution, 2015 (P.L. 113-164), which was signed into law on September 19, 2014, Congress authorized the President to arm and train vetted elements of Syrian opposition groups, including for purposes of deterring attacks on the Syrian populace by the Islamic State, but the legislation expressly provides that it does not constitute statutory authorization for the introduction of U.S. forces into actual or imminent hostilities."
CRS Report for Congress, R43720