	Introduction

In response to the September 11, 2001, terrorist attacks against the United States, Congress enacted the Authorization for Use of Military Force (2001 AUMF; P.L. 107-40 ; 50 U.S.C. §1541 note) to authorize the use of military force against those who perpetrated or provided support for the attacks. As armed conflict against Al Qaeda and the Taliban has progressed, and U.S. counterterrorism strategy has evolved, U.S. use of military force has expanded outside Afghanistan. The 2001 AUMF, as many have argued and the executive branch has agreed, does not seem to authorize all uses of military force in furtherance of U.S. counterterrorism objectives. Because the 2001 AUMF covers only some uses of military force to counter terrorist threats, other legislation and presidential powers under Article II of the Constitution provide authority to carry out U.S. counterterrorism activities globally. The Obama Administration, however, still finds itself relying on 2001 AUMF authority not only for continuing U.S. military operations in Afghanistan, but also for beginning a new campaign against the Islamic State in Iraq and Syria, and possibly expanding operations to other countries if the Islamic State or Al Qaeda groups or associates effectively expand their reach and pose a threat to U.S. national security and interests. The President, in his February 11, 2015, letter to Congress concerning his draft proposal for a new authorization for use of military force against the Islamic State, stated, "I remain committed to working with the Congress and the American people to refine, and ultimately repeal, the 2001 AUMF." In the face of these issues, Congress has for several years considered a number of legislative proposals to change the authority in the 2001 AUMF, the manner in which it is used, and the congressional role in its oversight and continuing existence. This process has continued in the 114 th Congress, and deliberations over the future of the 2001 AUMF have become entwined with consideration of proposals to enact a new AUMF to respond to the actions of the Islamic State in Iraq and Syria. In contrast to the authorization enacted by Congress in the 2001 AUMF, the legislation originally proposed by the Bush Administration in the wake of the September 11, 2001, attacks would have provided the authority to use military force not only against Al Qaeda and the Taliban, but also to counter all terrorist threats generally, without necessitating a connection to the attacks:
Resolved by the Senate and the House of Representatives of the United States of America in Congress assembled—
That the President is authorized to use all necessary and appropriate force against those nations, organizations or persons he determines planned, authorized, harbored, committed, or aided in the planning or commission of the attacks against the United States that occurred on September 11, 2001, and to deter and pre-empt any future acts of terrorism or aggression against the United States . U.S. military action in Afghanistan continues in a reduced form in 2015. Since the 2001 AUMF's enactment, presidential notifications to Congress have reported uses of military force, military deployments, and other activities in a number of countries and for a number of purposes, including to 
deploy U.S. Armed Forces and conduct military operations in several countries in a number of regions of the world, including most recently in Iraq and Syria against forces of the Islamic State and the Khorosan Group of Al Qaeda; counter generally the terrorist threat against the United States following September 11, 2001; engage terrorist groups "around the world"; engage terrorist groups "on the high seas"; detain individuals at Guantanamo Bay, Cuba, and to take other actions related to detainment decisions; and conduct trials of terrorist suspects in military commissions. Issues Concerning the Continued Use of the 2001 AUMF

The executive branch's reliance on the 2001 AUMF has raised a number of concerns among some Members of Congress and policy analysts.
In response to the September 11, 2001, terrorist attacks against the United States, Congress enacted the Authorization for Use of Military Force (2001 AUMF; P.L. 107-40; 50 U.S.C. §1541 note) to authorize the use of military force against those who perpetrated or provided support for the attacks. Under the authority of the 2001 AUMF, U.S. Armed Forces have conducted military operations in Afghanistan since October 2001. As armed conflict against Al Qaeda and the Taliban progressed, and U.S. counterterrorism strategy evolved, U.S. use of military force has expanded outside Afghanistan to include Al Qaeda and Taliban targets in Pakistan, Yemen, Somalia, Libya, and most recently, Syria.
The 2001 AUMF is not the sole authority for all U.S. uses of military force in furtherance of U.S. counterterrorism objectives; other legislation and presidential powers under Article II of the Constitution are invoked to carry out U.S. counterterrorism activities globally. Nevertheless, the Obama Administration still finds itself relying on 2001 AUMF authority not only for continuing U.S. military operations in Afghanistan, but also for beginning a new campaign against the Islamic State in Iraq and Syria, with the possibility of expansion to other countries if the Islamic State or Al Qaeda groups or associates effectively expand their reach and pose a threat to U.S. national security and interests. At the same time, the President has requested that Congress enact new authority for U.S. operations to counter the Islamic State and has expressed a continued commitment to "working with the Congress and the American people to refine, and ultimately repeal, the 2001 AUMF."
As the United States has engaged in counterterrorism and other military operations against Al Qaeda, the Taliban, and other terrorist and extremist groups over the past 13-plus years, many Members of Congress and legal and policy analysts have questioned the continuing reliance on the 2001 AUMF as a primary, effective authority for U.S. military action in a number of countries. Some have asserted that the 2001 AUMF has become outdated, unsuited to the challenge of countering terrorism and extremism in a changed world, at times claiming that the executive branch has relied on the 2001 AUMF for military action outside its intended scope.
Congress has for several years considered a number of legislative proposals to change the authority in the 2001 AUMF (by amending or repealing the law), the manner in which it is used, and the congressional role in its oversight and continuing existence. This process continues in the 114th Congress, and deliberations over the future of the 2001 AUMF have become entwined with consideration of proposals to enact a new authorization for use of military force to respond to the turmoil caused by the actions of the Islamic State in Iraq and Syria. Debate in Congress over the status of the 2001 AUMF may evolve in response to numerous developments overseas and U.S. policy responses. For further information on the Islamic State crisis, the U.S. response, and proposals to enact a new AUMF targeting the Islamic State, see CRS Report R43612, The "Islamic State" Crisis and U.S. Policy, by [author name scrubbed] et al., and CRS Report R43760, A New Authorization for Use of Military Force Against the Islamic State: Issues and Current Proposals in Brief, by [author name scrubbed].