War Powers: What Are They Good For?

A previous CNAS report identified the dangers of fixating on legislative action at the expense of informal tools Congress could use to shape the use of military force.¹ As that report also acknowledged, such legislative action is still sorely needed. This report elaborates on the four legislative pathways available to Congress to influence use of force decisions. The first course of action would use priority procedures and the National Defense Authorization Act (NDAA) to strengthen oversight, increase transparency, and exert political influence in order to build a foundation for future legislation to reform the War Powers Resolution, which provides the underlying legal basis for military intervention abroad, and update the existing authorizations for the use of military force (AUMFs). The second would introduce legislation to amend or replace the War Powers Resolution. This would amount to changing the process by which Congress adjudicates whether military forces may be introduced into hostilities. The past half century is replete with examples of this process failing to work as its authors envisioned. The third available legislative pathway would update the two AUMFs under which current overseas military operations are conducted. In recent years, these efforts have superseded broader, more generalized attempts to reform the War Powers Resolution. Finally, legislation reforming the War Powers Resolution and updating or revoking the AUMFs could be pursued simultaneously. This final course of action assumes that the War Powers Resolution and AUMF reform are part of the same political conversation.

These approaches are not mutually exclusive. Congress can and should continue to use priority procedures and the NDAA as legislative mechanisms to flex its war powers muscles. In addition to the immediate payoffs, such efforts could help pave the way for bigger reforms of the War Powers Resolution or the two existing AUMFs. These latter efforts constitute a much heavier lift, and there is reason to be skeptical that Congress will succeed. The potential for failure should not dissuade lawmakers from organizing a strong legislative push, although they might need to prioritize either the War Powers Resolution or the two existing AUMFs.

Project Background and Methodology

CNAS initiated a project to explore in depth the weakening of a key foundation of U.S. democracy: congressional oversight of American wars. The fruits of this investigation are taking shape in five areas: (1) “Congress’s Hidden Strengths,” an examination of the informal tools available to Congress; (2) three case studies that highlight successful (and less successful) congressional engagement on military operations; (3) an assessment of public opinion on the legislature’s role in war making; (4) a review of lessons learned from war powers and debates among key American allies (to be published); (5) this report, which examines four legislative pathways to a stronger congressional role. The findings and analysis in the present report derive from an extensive literature review, targeted interviews with congressional and executive branch staff, and the authors’ personal experiences.

War Powers Resolution: Background and History

The 1973 War Powers Resolution (WPR) represents Congress’s chief effort to give formal process and weight to its Article I powers of war declaration. At the time, the previous two centuries offered no repeatable precedent of executive-legislative division of labor in American military conflicts. The founders generated enough fodder to strengthen (or weaken) both branches’ claims to oversee war initiation: Thomas Jefferson sought authorization for conflict with the Barbary Pirates, but did not do so for a naval skirmish with the British; John Marshall’s position varied according to where he sat, whether during his stint in Congress or while he was chief justice of the Supreme Court.² Since its founding, the United States has engaged in dozens of instances of use of force abroad of varying size, and only around 10 percent of those engagements have been subject to a congressional war declaration or other authorization.³ Perhaps more remarkably, much of the time Congress did not object to such circumvention, or at least not authoritatively. Convenience and consolidation of support, not constitutionalism, drove much of this Article I compliance when it occurred, with similar motives undergirding any avoidance of congressional authorization. If there has been any consistency in when the president has sought authorization for war, or whether Congress has defended its apparent constitutional power, it has lain in the relevance of politics to those choices.

The 1973 War Powers Resolution, introduced in the wake of President Richard Nixon’s secret bombings of Cambodia, was meant to formalize a sequence of executive-legislative consultation, notification, authorization, and termination when placing U.S. forces in “hostilities.”⁴ The text of the resolution attempted to acknowledge the real significance of politics to these steps. Despite national unhappiness with the war in Vietnam, congressional anger at the administration’s unacknowledged Cambodian bombing, and the growing unpopularity of Nixon, the resolution was not the shrill reclamation of congressional authority that it might have been. The resolution’s on-paper provisions give both branches flexibility in execution, as well as breathing room to take the national temperature and assess political maneuver space at the outset of a conflict.

• Consultation: The resolution requires the president “in every possible instance” to consult Congress before introducing forces into hostilities. With “consultation” and even “Congress” undefined, the provision may be as symbolic, cursory, partisan, or drawn out as a president desires or Congress demands. At its best, consultation should be a natural element of the oversight relationship that is lacking today (see “Congress’s Hidden Strengths”).⁵ In practice, the executive branch has mainly treated this as a requirement for notification, often after having entered into hostilities.
• Reporting: The resolution demands a presentation of facts about the purpose, legal authorization, scope, and duration of a wide range of deployments, including and beyond hostilities. This requirement makes a small dent in evening out information advantages among the branches, insisting that the executive branch present, and Congress receive, a common narrative on the deployment of forces—but requiring no immediate action (indeed, the War Powers Resolution requires nothing of Congress in response to executive action—more political breathing room).
• Congressional “action”: When the executive branch notifies the introduction of U.S. forces into hostilities, the president must withdraw such forces from hostilities within 60 (or 90) days if Congress has not declared war or otherwise authorized these forces. Again, this provision privileges political risk considerations: there is no requirement for Congress to vote; a president need not seek a declaration of war; and the 60–90-day period allows for an assessment of the success of the intervention and the political response of constituents. In practice, successive administrations have further weakened this provision by never acknowledging the specific provision in their reporting, or by limiting its applicability to interventions. Legal challenges from Congress attempting to force such reporting have been repeatedly dismissed.

In practice, rather than empowering shrewd assessment and maneuvering based on electoral and operational winds at the outset of a conflict, the political considerations embedded in the WPR have enabled a state of “congressional passivity.” National security law expert Matthew Waxman notes that, “Members of Congress often have little to gain electorally by taking a firm stand on military intervention and much to lose if those military campaigns go awry.” Instead of empowering them, the WPR codifies their “luxury of watching, waiting, and criticizing from the bleachers.”⁶

The authors of the WPR tried to give Congress both legislative teeth and a limited political buffer in the sections requiring the president to remove forces if Congress so directs by concurrent resolution. Such a measure is subject to priority procedures that lift it to the top of the legislative pile for both committee consideration and a full chamber vote, and it does not go to the president’s desk.

After the 1983 Supreme Court case Immigration and Naturalization Service (INS) v. Chadha raised questions about whether these components of the WPR would amount to an unconstitutional “legislative veto,” the Senate filled in the gap with new language that again provided for expedited consideration (using the mechanisms of Section 601(b) of the International Security and Arms Export Control Act of 1976), with a requirement to send such legislation to the president.⁷ The House has not adopted similar priority procedures for joint resolutions. True, this revised process has raised the bar to a veto-proof supermajority if Congress wishes to assert its power to force withdrawal of U.S. forces. But it nevertheless enables—and sometimes forces—Congress to assert its voice, publicly, on matters of military intervention, without the barriers of recalcitrant leadership, filibusters, or other procedural hurdles.

Article of Faith: Challenges to Congress’s Formal Role in War Making

Critics of Congress’s relative weakness in matters of war and peace often suggest an inherent fecklessness in the institution. But this characterization ignores structural and political barriers that hinder Congress from exercising its war-making powers. The same disincentives also shape interest in reforming war powers. Such challenges are not negligible and calls to reassert Article I power based on constitutional merit or support for the armed forces are not enough to move Congress as a body.

Observers might presume that a recent increase in congressional activity regulating force abroad demonstrates a growing ability to overcome these barriers. But congressional activism in recent years has employed strategies that either deliberately address the challenges or purposely work around them. The passage of the Yemen War Powers Resolution, the sustained interest in repealing the 2001 AUMF, the launch of new requirements for executive reporting on use of force, and the recent exploration of War Powers Resolution reform were each driven by disparate interests: the strong executive, diffusion of war-making powers within Congress, and politics and military intervention. Members may be driven by support for or opposition to a specific military intervention, or instead may simply wish to preserve their Article I relevance while remaining aligned with an administration’s strategy. The increase in legislative activism, then, is not necessarily indicative of growing antiwar sentiment or even an increased willingness to oppose the president.

The strong executive: Since it was passed into law, the War Powers Resolution has been deemed unconstitutional by every president. Members of Congress have been politically and legally constrained (via the stripping of the “legislative veto” in INS v. Chadha) from a more active role in war making by a widely held belief that “presidential leadership is essential to successful foreign policy.”⁸ The executive branch possesses inherent advantages over Congress on use of force decisions. The legislature cannot fully replicate a president’s control over federal agencies, his singular authority in foreign affairs, and his operational control as commander in chief. In practice this gives the president advantages in information, via larger bureaucratic resources; narrative setting, via the president’s bully pulpit; and time, via his immediate military command authority. The president speaks with one voice, where Congress is hard pressed to do so even within a party caucus. With this advantage, the president is able to draw national attention to the executive’s view of urgent threats and risks to American national security interests. Members of Congress are acutely aware of their own role in this signaling: their reactions to the executive’s justification for intervention may be viewed as representative of domestic resolve or strength and are closely observed by potential adversaries.

The executive branch has flexed these inherent advantages to steamroll congressional authority under the WPR, whether by limiting relevant definitions in the authority, evading the requirements that would mandate action by Congress, or gradually expanding scenarios in which presidents could use force without congressional authorization. These larger actions have produced a record of often poor communication, information sharing, and oversight relationships, and Congress is the clear underdog.

Still, members have a range of options available to influence decision-making. These include using their own forums for gathering information or establishing narratives to rival the president’s, as detailed in the earlier report “Congress’s Hidden Strengths.” Members can likewise regain some parity by shifting a portion of their attention from the narrow act of conflict initiation—where executive power is at its strongest—to the “long series of steps and counter-steps, actions and inactions” that precede and follow the launch of military interventions.⁹

Diffusion of war-making powers within Congress: The Foreign Affairs and Foreign Relations committees are designated in the War Powers Resolution as referring committees; to the degree that any body in Congress is “in charge” of war powers, it is these two. But war initiation is a single point on the spectrum of conflict, and overemphasizing Congress’s role in authorizing or declaring war ignores the long prelude and tail to such interventions—and Congress’s potential role in both.¹⁰ Alliances, security cooperation and assistance partnerships, the prioritization and availability of intelligence tools, defense, budgets, posture and planning, technological control and resiliency—all of these, and more, are sometimes crucial steps preceding possible intervention. Oversight of them is dispersed among disparate congressional committees that have little incentive and process established for information sharing, collaboration, or connecting their own dots.

These jurisdictional challenges continue after conflict is initiated. A classified counterterrorism operation, a military advising program, an embassy security challenge, and military base construction all fall among separate committee jurisdictions, even if they take place simultaneously in the same theater of operations. Separately, these challenges may receive sufficient oversight attention unto themselves. But Congress and congressional staff are jurisdictionally and culturally disinclined to view them as part of a spectrum of conflict.

Individual efforts to regulate military intervention, or to more broadly reform the process, must either address these limitations or find means to work around them. That said, some committees feel this lack more acutely than others; the Armed Services Committees in the House and Senate (HASC and SASC) are larger and better staffed, and sometimes maintain better oversight relationships with their Department of Defense (DoD) counterparts than their committee peers. The HASC and SASC are also better empowered—or make better use of their powers—to oversee military intervention because of their consistent access to an authorization bill governing the DoD’s policy and use of resources. Any serious effort at regulating conflict or renewing Congress’s war powers should understand that Congress has greatest influence when it approaches conflict as a continuum across committees, rather than as a jurisdictional smorgasbord. This approach demands understanding formal and informal barriers that limit committee cooperation, agency-committee information sharing, and the relative power dynamics of committees. The approach necessitates either mitigating these matters with creative coalitions, or else incorporating them into reform efforts.

Politics and military intervention: From a political perspective, members of Congress have limited incentive to formally engage on the use of force, or to refine their war powers processes to increase their role. Foreign policy, as a rule, tends not to drive elections,¹¹ and taking ownership of military intervention policy risks members also owning blame that they could have avoided.¹² Intense political polarization has restricted opportunities for foreign policy cooperation across party lines, and partisanship has colored support of or opposition to military intervention among both members of Congress and the American people.¹³ Public opinion surveys assess that partisan lenses impact how individuals judge the costs of conflict, their overall trust in the military, and their understanding of the results and lessons of intervention.¹⁴ A frequently cited exception to these findings—public, bipartisan concern about the Iraq War in 2006, or Democrats using that midterm election as a referendum on Iraq policy—ultimately generated a new political precedent deterring congressional action. President George W. Bush and his allies on the Hill reframed debate around an unpopular war by offering a change in strategy (the Iraq surge). The strategy’s relative success, combined with the notion that support for troop withdrawals amounted to a dangerous defeatism, continue to shape the politics of war oversight.¹⁵

These trends put distance between democratic accountability and use of force, and they also coarsen “U.S. sensibilities when it comes to the consequences of military action.”¹⁶ The distance is, in turn, reinforced by an executive branch that has come to benefit from such freedom of action, pursuing operational approaches that are less clearly subject to congressional regulation or public attention.¹⁷ To counter this cycle of political apathy on military matters, some advocates have suggested a range of policy shocks designed to force the American public to feel the impact of military interventions and elevate their political consciousness—a renewed military draft, for instance, or the imposition of war taxes.¹⁸ Such measures are politically unlikely at best and harsh overreactions at worst, particularly when the goal of “well-informed citizens electing members of Congress who play the policing role that we would wish for them” is on the surface unobjectionable.¹⁹

The American people send mixed messages regarding their expectations—intervention in Iraq and Afghanistan are increasingly unpopular, while alliances and military superiority remain priorities—but there is clearly room for something more than ingrained passivity.²⁰ To generate a new politics around use of force, advocates will need to work multiple factions that maintain contravening interests and goals. Antiwar advocates, congressional power constitutionalists, restrainers, and those who wish to set clear goals around military objectives have found common cause in recent years. This coalition will need to expand to include those who wish Congress not merely to restrain an executive bent on the use of force, but to weigh in on its use through the spectrum of war initiation and execution—sometimes curbing a president, sometimes tempering his withdrawal impulse, and other times seeking to enhance the quality of ongoing operations.

Changing Nature of Warfare

The greatest challenge to congressional attempts to regulate, oversee, or apply process to military intervention is the nature of modern conflict itself. The diverse means by which the United States can or does pursue war challenges Congress jurisdictionally and legally, and raises threshold concerns when America is at war that have not been effectively aired. The evolving war on terror presents one dimension of this problem. As Matthew Waxman and Jack Goldsmith note, “The United States wields military force today in ways starkly different from 2001. The conflict that began fifteen years ago has been characterized by ever-morphing enemies, an uncertain though expanding geographical scope, and an indefinite duration, unlike any war in previous eras in U.S. history.”²¹ There are, today, no restrictions to the location, duration, or size of intervention under the 2001 AUMF, and the executive branch has been liberal in its inclusion of entities labeled as co-belligerents. Despite their size and secrecy, operations conducted under the post-9/11 authorization have “foreign policy, strategic, and reputational consequences for the United States, akin to much heavier deployments, yet much less public examination.”²²

But much of today’s war on terror is enabled, rather than fought, by U.S. forces, in “by-with-and-through” counterterrorism interventions conducted under security assistance and cooperation authorities, not under an AUMF. These increasingly popular operations occur on the continuum of conflict—their purpose is to enable foreign forces that are themselves potentially at war—but they are not treated as such from a risk, policy, or legal perspective. A case study of the 2017 ambush of U.S. forces in Niger highlights concerns about whether overseers, policymakers, and implementers have accurate understanding about the specific authorities (legal, operational, fiscal) related to train, advise, assist, and accompany missions. “Even if we can identify where the line between support to combat and involvement in combat is, how much control does anyone really have over crossing it?” one interviewee asked.²³ This legal position of “collective self-defense” could embroil the United States in escalating hostilities without clear congressional intent, or even without notification to Congress, because actions by U.S. forces supposedly fall under the umbrella of an existing authorization.²⁴

Conflict that skirts congressional oversight is not limited to the counterterrorism realm. Cyberwarfare is not contemplated in the text of the War Powers Resolution, and its constraints may not apply to some conventional uses of force deployed remotely. Many current “gray zone” or “hybrid warfare” concepts highlight a range of escalatory steps that demand no war powers reporting or are not commonly understood as part of modern conflict. While these low intensity, quiet, or remote tactics are a feature operationally, they are problematic for U.S. democracy. Public debate and political checks reduce error as well as excess, and they promote legitimacy—but they cannot function effectively when operations are characterized by stealth.²⁵

Reforming the Process: The War Powers Resolution

Demonstrating acute awareness of Congress’s limitations when it comes to regulating warfare, presidents have put U.S. forces in harm’s way more than 100 times without congressional authorization since the WPR was passed. As James A. Baker and Warren Christopher—co-chairs of the congressionally mandated National War Powers Commission—wrote in the Commission’s 2008 final report, the WPR “tends to be honored in the breach rather than by observance.”²⁶ The Commission detailed numerous weaknesses in need of redress, and the lack of consensus on how to address them.

The issue is not whether the War Powers Resolution would benefit from reform, but rather whether successful reform or replacement legislation is feasible, given the serious barriers to it. The challenges described here engender a considerable degree of ambivalence in Congress when it comes to reclaiming war powers authority from the president. Some experts believe it has become nearly impossible to regulate the full spectrum of conflict under a single legislative scheme, and that doing so, if it were possible, could undermine the executive branch’s agility to the detriment of U.S. national security.²⁷ Others question whether the legal and political realities make meaningful reform impossible.²⁸

Skepticism is warranted. Yet, without a more effective statutory framework, Congress will never be able to engage as a co-equal player in matters of war and peace. Congress has been unable to fulfill its Article I responsibilities, and this is unlikely to change without substantive reform. On policy grounds, imposing stronger congressional checks could help test whether U.S. interests are served by entering into armed conflict, improve the conduct of American operations, and affect the setting of objectives and deadlines. Simply ceding the field should not be an option.

Lawmakers have made numerous attempts to reform the WPR, far too many to catalogue in this report. These efforts have taken various forms. There is no consensus on the right legislative language; if there were, Congress would have already legislated reforms. There is also a risk of oversimplifying the complexity involved in amending or replacing the WPR. At the risk of doing so, however, it is possible to identify three major areas where lawmakers might focus.

First, the resolution’s failure to define hostilities is perhaps its most fatal flaw. Successive administrations—Democratic and Republican—have seized on the lack of specificity to evade the reporting requirement that, in theory, should be triggered whenever U.S. forces enter hostilities. The justification for this has been simply that before entering them, hostilities are neither present nor imminent. This, in turn, renders moot the stipulation that the president must withdraw forces if Congress does not authorize their use within 60 to 90 days.²⁹ Changes in the nature of warfare have muddied the issue even further, making it harder to define hostilities and easier for the president to avoid seeking congressional authority.

Numerous proposals have attempted to fix the trigger mechanism by defining “hostilities” and “imminent hostilities” in order to stop presidents from avoiding their reporting requirement by claiming these situations are not present on the ground.³⁰ The most straightforward approach is to formally adopt the descriptions in the original House Report on the WPR, which defined “hostilities” as situations where fighting had begun as well as situations “where there is a clear and present danger of armed conflict;” and defined “imminent hostilities” as situations where there existed a “clear potential” for either of these states arising.³¹ Other proposals have employed narrower, broader, or more tailored definitions depending on the context in which they were proposed.³² In order to account for the changes in the nature of warfare, Oona Hathaway, a professor of international law at Yale Law School, has proposed aligning the term “hostilities” with the definition of “armed conflict,” for which there exists substantial and robust legal authority in domestic and international law, and adding specific requirements for functions the military was not performing in 1973.³³

Second, the War Powers Resolution employs an overly narrow definition of the president’s powers (Sec. 2c), which it states apply only if Congress has declared war or passed a specific statutory authorization, or if there is an attack against the United States or armed forces. Some would-be reformers argue that the limitations this imposes are unconstitutional, whereas others consider it simply impractical.³⁴ For example, under a plain reading of the text, a president could not legally preempt an imminent attack, defend an ally, or engage in hot pursuit of an attacking party without congressional authorization. Either way, these limitations have essentially set up the WPR to fail. One solution would be to transform the limitation on presidential authority into a general authorization to deploy troops, subject to other provisions of the resolution.³⁵ Another would be simply to repeal the subsection and focus on strengthening other provisions.³⁶

Regardless of which approach Congress takes, the recent expansion of existing AUMFs has highlighted a need to build in checks at the outset. One way of doing so would be to amend the War Powers Resolution to include requirements that kick in any time Congress passed an authorization for use of military force. Recent legislation by Representative Peter DeFazio includes text that may be useful in this regard. Requiring a specific statutory authorization for introduction of the armed forces into hostilities, it specifies that this must:

1. Clearly define the mission, objectives, and geographic scope of the Armed Forces;
2. Require the president to seek from the Congress a subsequent specific authorization to expand the mission, objectives, or geographic scope of the Armed Forces; and
3. Provide for termination of the authorization for such use of the Armed Forces unless the Congress enacts a joint resolution providing a subsequent specific authorization for such use of the Armed Forces.³⁷

Third, the War Powers Resolution lacks an effective mechanism for compelling presidential compliance. The chief means of enforcement granted to Congress—that if it adopts a concurrent resolution directing the withdrawal of U.S armed forces, then the president must comply—is now considered by many to be unconstitutional in light of the Supreme Court’s decision in INS v. Chadha.³⁸

One way of addressing the lack of enforcement would be to strengthen the language regarding judicial remedy. Another would be to use Congress’s power of the purse, and link presidential noncompliance to an automatic termination of relevant appropriations.³⁹ For example, Congress could stipulate that it must explicitly authorize the use of military force after troops have been introduced into hostilities or situations where hostilities are imminent, failing which funding will be either terminated automatically or subject to an up-down vote on an expedited basis. This approach to enforcement would be effective, but also politically fraught. Many lawmakers would be reluctant to cut off funding for U.S. troops or allow that funding to be cut off automatically as a result of congressional inaction.

Proponents of war powers reform should not negotiate against themselves at the outset, especially given the range of infirmities that require redress. Indeed, even real progress on all three of these areas would still yield an imperfect legislative framework. It is equally true, however, that progress on any of them would be a major step forward.

Reform in Practice: The 2001 and 2002 AUMFs

The War Powers Resolution delineates three circumstances in which the president can introduce troops into hostilities or situations where hostilities are imminent: a declaration of war; a specific statutory authorization; and a national emergency created by attack on the United States, its territories or possessions, or its armed forces. Congress has not declared war since World War II but rather passed resolutions authorizing the use of military force, including twice in the past two decades. Unlike unilateral uses of force conducted under the president’s Article II authority in response to a national emergency, wherein the 60-day clock theoretically starts ticking if the president follows proper reporting procedures, these two AUMFs have no domestic-law limitations on the geographical scope, duration, or intensity of force used to accomplish the missions they authorized.⁴⁰

The 2001 Authorization for Use of Military Force allowed the president to use force against “those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons.”⁴¹ The 2002 AUMF gave the president the authority to defend the United States against the continuing threat posed by Iraq when the country was led by Saddam Hussein, who then-President George W. Bush told Congress possessed weapons of mass destruction and was willing to use them against the United States.

Beginning in late 2014, various members of Congress began proposing legislation to repeal or replace the 2001 AUMF, and to repeal the 2002 AUMF. The trigger for this flurry of activity was the emergence of the Islamic State of Iraq and Syria (ISIS), and specifically the question of whether using armed force against it required Congress to pass a new authorization or amend an existing one. The answer rested upon how the scope of missions authorized in the 2001 and 2002 AUMFs were interpreted, which, in turn raised questions about whether they needed to be repealed or replaced.

The Bush and Obama administrations interpreted the 2001 AUMF to include not only al Qaeda and the Taliban, but also associated forces that “entered the fight alongside al Qaeda or the Taliban” and were “co-belligerent[s] with al Qaeda or the Taliban in hostilities against the United States or its coalition partners.”⁴² Congress affirmed the inclusion of associated forces in a provision of the 2012 NDAA codifying detention authority under the 2001 AUMF.⁴³ The Obama administration maintained that ISIS qualified as an associated force because it was the successor to al Qaeda in Iraq, and that remained the case even though the two broke ties in 2014. Moreover, the administration extended the concept of “associated forces” to apply to ISIS affiliates outside of Iraq and Syria as well.⁴⁴ In addition to expanding the scope of the AUMF in terms of the groups covered, the administration expanded the use of ground forces beyond Afghanistan as well.

Obama did not need to rely on the 2002 AUMF to use military force against ISIS because of his reliance on the 2001 AUMF. Indeed, his administration had previously asserted that with U.S. troops having completed their withdrawal from Iraq, the 2002 AUMF was “no longer used for any U.S. government activities,” and that the Obama administration “fully support[ed] its repeal.”⁴⁵ His administration’s legal position was, however, that as long as the 2002 AUMF was on the books, it could serve as an alternate statutory authority to support operations against ISIS, since an Iraq controlled by the group would pose a threat to the United States.⁴⁶ Furthermore, the administration asserted that it could use force against ISIS in Syria in the collective self-defense of Iraq.⁴⁷

The proposals generated between 2014 and 2018 took different forms. Some would have repealed the existing AUMFs in favor of a new authorization that covered al Qaeda, the Taliban, and ISIS. Others left the 2001 AUMF in place and proposed a new authorization of force against ISIS. Most repealed the 2002 AUMF. All these proposals wrestled with a similar set of issues: whether and how to define associated forces, and what the process should be for adding additional ones or expanding the scope of an authorized mission; whether to limit ground operations, and if so what the limits and reporting requirements should be; and when, if ever, the authorization in question should sunset. Most proposals left it up to the president to decide whether to expand the scope of the mission, but a significant number also required notification to Congress when this occurred.⁴⁸ A subset of these also drew on the War Powers Resolution to provide expedited procedures for removing an authorization against an associated force.⁴⁹ Some proposals also drew inspiration from war powers debates, or referenced the resolution directly, in provisions that placed limitations on the conduct of ground combat operations.⁵⁰

The attempts at AUMF reform did not address whether self-defense and “collective self-defense” were covered under existing or proposed authorizations. According to U.S. standing rules of engagement, “Unit commanders always retain the inherent right and obligation to exercise unit self-defense in response to a hostile act or demonstrated hostile intent.”⁵¹ U.S. forces have exercised this right to inherent self-defense against Shia militias in Iraq and most likely in other places as well, such as Somalia.⁵² Over the past several years, the executive branch has increasingly asserted that “collective self-defense” is authorized under the existing AUMFs, including against entities not explicitly covered by those AUMFs. A letter addressed in 2019 to the Chairman of the House Committee on Foreign Affairs states that “the Administration has not, to date, interpreted either AUMF as authorizing military force against Iran, except as may be necessary to defend U.S. or partner forces engaged in counterterrorism operations or operations to establish a stable, democratic Iraq” (emphasis added).⁵³

At issue is not whether the United States is justified in using force in these instances, but rather if the 2001 or 2002 AUMF should be used as legal justification. The executive branch could rely on its Article II powers, in which case any use of force must be limited in scope unless Congress passes a new authorization. Instead, the executive branch is arguing that Congress already granted it statutory authority under the existing AUMFs to use force to protect U.S. or partner forces against entities not covered under either AUMF, because the need for self-defense arose in the course of engaging actors covered under one of them.⁵⁴ This practice of expanding the AUMFs to include actors that have no ties to al Qaeda, ISIS, or 9/11 has put the United States on a slippery slope. After killing Iranian Quds Force commander Qasem Soleimani in January 2020, President Trump argued that Congress had indirectly authorized the strike under the 2002 AUMF. He also vetoed legislation passed by Congress refuting his interpretation of the law.⁵⁵

None of the various AUMF proposals introduced ever made it off the floor of either chamber, much less into law. Republicans, by and large, did not feel a great sense of urgency. They were open to updating the 2001 AUMF to include the Islamic State, or to passing a new authorization specifically for the group, provided it came with minimal limits on executive power. Because they did not want to restrict the president, even President Obama, from waging the war against terrorist groups, the status quo suited them. Progressive Democrats wanted to repeal the existing AUMFs and favored either a restrictive replacement such as the one Senator Jeff Merkley proposed or none at all. More moderate Democrats and some Republicans sought to chart a middle path for any new authorization but could not bring along enough members from either side.

The politics of AUMF reform have not changed considerably in the past several years. Congress came close to repealing the 2002 AUMF in 2019, with an amendment to the House-passed version of the NDAA. The Senate killed it in conference. Representative Barbara Lee, who authored the amendment, also introduced standalone legislation earlier this year to repeal the 2002 AUMF. This legislation passed the House but is expected to die in the Senate. It will likely take a major push from the president, or at least considerable White House support, to resuscitate and pass AUMF reform.

The devil is always in the details, but enough ink has been spilled on the subject to identify key components of reform:

• An updated authorization to use force against specific groups and/or in specific countries, with a mechanism for adding new ones: Because many lawmakers are likely to evince concerns that Congress cannot or will not authorize force quickly enough to meet new threats, it could create a listing system modeled on the State Department’s Foreign Terrorist Organization designation process, whereby the executive branch must meet certain specified criteria to add new groups under the AUMF. For lawmakers concerned about ceding authority to the executive, Congress would then be able to exert influence by specifying the criteria. It could also make additions subject to congressional review within a certain time period or on a quarterly basis. This approach would increase transparency and provide Congress with more influence over when a group is added than the current process affords.⁵⁶
• Criteria establishing the upper limits of military force: These could be used to address specific and discrete threats before the president has to return to Congress for additional authorization.
• A provision stipulating the need for review and renewal every three years, with a default sunset if Congress does not renew the authority: In addition to avoiding the current situation, in which AUMFs enable perpetual war, a sunset without review and renewal would provide another opportunity (and a forcing function) to reconsider the executive branch’s inclusion of any additional groups under the regime outlined above.
• A description of criteria defining when the president would be authorized to use military force in self-defense of U.S. troops, or when collective self-defense of partners would be authorized against entities not covered under the AUMF: Such criteria would clarify how and when the latter situation could enable efforts to combat entities that the AUMF does cover.
• Reporting requirements: These should include a list of all entities for which a determination has been made that force could legally be used under the AUMF, including the legal and factual basis for such determination, a description of whether force has already been used against each such entity, the actions taken pursuant to the AUMF, and estimates of civilian casualties. Congress has created many of these requirements for the 2001 and 2002 AUMFs using the NDAA, and it could build upon these ad hoc legislative efforts for a new authorization.

Exerting Political Influence: Using Priority Procedures

Although Congress has failed to impose legal checks on the use of force, it has used the constitutional tools and legislative mechanisms at its disposal to exert political influence on the executive branch. Public support for the president and his military policies often has declined when Congress dissents, meaning Congress can influence a president’s use of force even if it fails to enact legislation to halt it.⁵⁷ Lawmakers can use hearings, public statements, and standalone legislation to accomplish this objective. One of the challenges related to legislation is that it can be difficult to ensure new bills get floor time, especially in today’s hyper-partisan environment. The National Defense Authorization Act, which is discussed in more detail in the following section, offers one alternative route, because it has come to be seen as must-pass legislation. The use of priority procedures associated with the War Powers Resolution is another. As Scott Anderson observed in 2019, priority procedures can “empower even small groups of legislators to elevate and force a public debate on qualifying issues, thereby bringing political pressure on other members of Congress and the president to justify or change their position.”⁵⁸

In early 2019, a small bipartisan majority in the U.S. Senate took advantage of priority procedures associated with the WPR to adopt a joint resolution (S. J. Res. 7) requiring President Trump to “remove United States Armed Forces from hostilities in or affecting the Republic of Yemen, except United States Armed Forces engaged in operations directed at al Qaeda or associated forces.” The resolution defined “hostilities” as including “in-flight refueling of non–United States aircraft conducting missions as part of the ongoing civil war in Yemen.”⁵⁹ In layman’s terms, Congress directed the Trump administration to end aspects of its support for the Saudi-led intervention against the Houthis in Yemen. The House of Representatives passed the same bill weeks later. Although Congress has infrequently cut off funding for operations that involved U.S. troops in hostilities, this was the first time Congress ever passed legislation requiring the president to withdraw U.S. armed forces from a conflict. President Trump subsequently vetoed the bill, but the effort to curtail U.S. support for Saudi Arabia and its coalition partners has cracked open the door for Congress to claw back some of its war powers authority.

The first thing to note in this regard is that S. J. Res. 7 generated debate about the definition of hostilities. The United States has provided logistical support, including air-to-air refueling, intelligence sharing, advisory assistance, and defense articles and services to the Saudis and Emiratis.⁶⁰ This support makes the United States a party to the conflict according to international law.⁶¹ However, U.S. forces have not been “introduced into hostilities” as per the traditional executive branch interpretation of the War Powers Resolution, which is “a situation in which units of the U.S. armed forces are actively engaged in exchanges of fire with opposing units of hostile forces.”⁶² The authors of S. J. Res. 7 noted that the WPR definition includes situations where members of the U.S. military “command, coordinate, participate in the movement of, or accompany” foreign military forces that are themselves engaged in hostilities.⁶³ They argued that aerial refueling falls within this definition.⁶⁴

In vetoing the bill, President Trump hewed to the traditional executive branch interpretation and argued there were no U.S. forces engaged in hostilities to withdraw.⁶⁵ The Trump administration’s interpretation of hostilities is longstanding, and it would be unlikely that courts would side with Congress, if they even chose to intervene.⁶⁶ Nevertheless, because joint resolutions may supersede earlier statutes, S. J. Res. 7 signifies a notable effort to establish a broader definition. At the very least, the inclusion of aerial refueling in legislation that passed both chambers cracked open the door for renewed debate on whether to clarify the War Powers Resolution, and, if so, how to define hostilities.

Second, the effort to end support for the Saudi-led coalition showed the extent and limits of the priority procedures in the WPR. Post-Chadha, Congress can no longer rely on the adoption of a concurrent resolution to force the president to remove armed forces from hostilities. Its ability to use an additional set of priority procedures enacted in the Senate to fast-track a joint resolution means that Congress could still force a vote, but must contend with a presidential veto. S. J. Res. 7 was the culmination of numerous legislative attempts over several years to end U.S. support for the Saudi-led coalition.

Although its proponents failed to garner the necessary two-thirds majority needed to override President Trump’s veto, or to end all U.S. support for the Saudi-led intervention, they succeeded in using priority procedures to keep legislation moving and force their colleagues to take tough votes on the issue. The effort ultimately garnered bipartisan support for S. J. Res. 7 and put sufficient political pressure on the Trump administration to end aerial refueling and work harder to bring an end to the conflict in Yemen. In doing so, the proponents of S. J. Res. 7 provided a roadmap for future efforts to press the executive branch on issues related to the use of force. Congress used this roadmap in an attempt to restrain the president regarding Iran, which is discussed further shortly.

Third, the bipartisan coalition that supported S. J. Res. 7 has had some staying power. As Scott Anderson notes, when the Trump administration used an emergency waiver to bypass congressional opposition to certain Yemen-related arms sales in May 2019, many of the legislators who supported S. J. Res. 7 also backed a series of 22 joint resolutions disapproving of those sales.⁶⁷ Perhaps more strikingly, six of the seven Republican senators who backed S. J. Res. 7 also voted for S. J. Res. 68, the joint resolution to direct the removal troops from hostilities against Iran that have not been authorized by Congress.⁶⁸ There was less carryover in the House of Representatives, which is typically the more partisan chamber. Only four of the 14 members who supported S. J. Res. 7 also voted for S. J. Res. 68.⁶⁹

S. J. Res. 68, which came in the wake of the Soleimani killing, directed the president to “terminate the use of United States Armed Forces for hostilities against the Islamic Republic of Iran or any part of its government or military, unless explicitly authorized by a declaration of war or specific authorization for use of military force against Iran.” The findings section of the joint resolution also clarified that the 2001 and 2002 AUMFs “do not serve as a specific statutory authorization for the use of force against Iran.”⁷⁰ Although findings do not have the force of law, they nevertheless clearly signal congressional intent. President Trump vetoed this joint resolution as well, but the legislative effort made clear that the majority of Congress does not support going to war against Iran without congressional authorization.

Playing Small Ball: Using the NDAA

Most legislation that is introduced annually dies: in committee; on the floor of the House or Senate; for lack of bicameral action; or, more rarely, once it reaches the president’s desk. The National Defense Authorization Act, which Congress has passed every year for six straight decades, is an exception. Members consider it must-pass legislation, which every president feels immense pressure to sign into law. As a result, the NDAA could be a vehicle for moving provisions and amendments that would not otherwise become law.⁷¹ Lawmakers have used the NDAA to try to repeal the 2002 AUMF, prohibit the use of force against Iran unless authorized by Congress, and end support for the Saudi-led intervention in Yemen. These provisions did not survive conference, but other provisions that strengthened congressional oversight, increased transparency regarding the use of force, and built a legislative foundation for future reforms have become law.

Congress can conduct oversight without passing legislation, but a thorough approach necessitates legislative action. The hearings, briefings, trips, and other tools that “Congress’s Hidden Strengths” identified as useful for shaping current conflicts often require reporting from the executive branch in order to identify and elucidate critical issues. For example, although the Obama and Trump administrations notified Congress that they were deploying combat-equipped troops to Niger, both administrations also stated that these forces were deployed to conduct security cooperation with local forces and not under the 2001 AUMF. As a result, committees and staff with responsibility for conflicts conducted under a congressional authorization were not closely monitoring the activities of U.S. forces in Niger. Only after four American soldiers were killed, in the 2017 Tongo Tongo ambush on an operation to capture an Islamic State Sahel commander, did the Trump administration invoke the AUMF. Congress already lacked information about the array of associated forces covered under the AUMF. The Tongo Tongo ambush raised questions about when and where security cooperation activities that blur the line with combat might retroactively become “AUMF-able.” Lawmakers included several provisions in the NDAA to improve congressional oversight.

First, Section 1285 requires a recurring, semi-annual report describing any “actions” taken pursuant to the 2001 AUMF against countries or organizations implicated therein. This report serves as an important “flag” for staff in terms of areas or activities where they should focus attention. Section 1285 also requires the executive to provide a legal and factual basis for invoking the AUMF to ensure the authority is not being misapplied, as well as to describe the threats posed by the actors against whom the United States took actions under the auspices of the AUMF, and the actions taken.

Second, the 2020 NDAA amended Section 1264 of the 2018 legislation, which required reporting from the executive on the legal and policy frameworks for the use of force. The amendment transformed a one-off notification of any changes to these frameworks into an annual report that includes an unclassified portion listing all such changes and the legal, factual, and policy justifications for making them. Congress also required that the 1264 report, as it has become known, include a list of all foreign forces and others against whom force could legally be used under the AUMF.⁷²

In addition to improving oversight, lawmakers have also been able, through NDAA amendments, to increase public transparency regarding the use of force, and to apply pressure on the executive branch. For example, Congress used the 2020 NDAA (Sec. 1274) to require a report on civilian casualties caused by the Saudi-led coalition and by the Houthis in Yemen. This report also must assess whether each side is complying with the laws of armed conflict. When amending Section 1264 of the 2018 NDAA, Congress also mandated that the annual report include an unclassified list of all changes and the justifications for making them. Making this type of information public could help provide the media and advocacy organizations ammunition to press for legislative and executive branch reforms.

Perhaps the greatest benefit of the NDAA is that because lawmakers can count on it to pass annually, they can use it to pursue incremental and iterative reforms. There are several advantages to this approach.

First, it enables Congress to tailor legislation to the executive branch performance. The 2019 NDAA required the Department of Defense to designate a senior official to oversee its policies regarding civilian casualties. Based on oversight of the DoD, Section 1282 of the 2020 NDAA clarified congressional expectations and required the senior official in question to improve coordination with the Department of State and chiefs of mission. Congress also included an NDAA provision (Sec. 923) requiring the DoD to conduct an assessment of the resources it needs to fulfill its congressional mandate.

This responsiveness can also be used to address executive branch malfeasance. For example, the 1264 report named for the section reference above required the director of national intelligence (DNI) to publicly report any U.S. lethal action and resulting casualties outside of “areas of active hostilities,” the term of art used for active war zones. After President Trump issued an executive order asserting that the DNI would no longer provide this information, Congress responded with Section 1723 of the 2020 NDAA, requiring “a report on the number of strikes undertaken by the United States against terrorist targets outside areas of active hostilities,” along with an estimate of resulting casualties.⁷³

Second, and perhaps more important, the NDAA provides lawmakers an opportunity to create legislative scaffolding on which they can build over time to realize a longer-term vision for reform. This may not have been the original intention with Section 1264 of the 2018 NDAA, or with the civilian casualty requirements in the 2019 NDAA, but the evolution of both illustrates how lawmakers can lay the groundwork with an initial amendment and then adapt it over time. An incremental approach such as this provides space to flesh out thinking on new problems, for instance where partnered operations fit into the concept of hostilities. As an example, Section 1754 of the 2020 NDAA tasks the DoD with developing a comprehensive policy on the use or provision of collective self-defense that includes, among other things, a clarification of the legal bases providing authorization to engage in it.

An incremental approach could also be advantageous where there is a need to slowly build consensus on sensitive issues such as the 127e program that permits the DoD to spend up to $100 million supporting surrogate forces that conduct missions designed to achieve U.S. counterterrorism objectives. The 2020 NDAA limits the use of funds to ensure that money is spent to support or facilitate only authorized operations, and it strengthens congressional oversight to require descriptions of the operations, the legal basis for conducting them, the support provided, and the recipients of such support. Congress stopped short of mandating a description of the entities with which the recipients of support are engaged in hostilities, and whether each such entity is covered under an authorization for use of military force. Lawmakers took steps to address this omission with an amendment to the 2021 NDAA that includes various other requirements intended to ensure, among other things, that 127e funds are spent in accordance with U.S. priorities.

It is possible that, over time, this incremental approach could also be used to establish or reinforce precedent.⁷⁴ Section 1285, which, as mentioned, mandates a semi-annual report on actions taken pursuant to the 2001 AUMF, also requires a description of “any actions taken to command, coordinate, participate in the movement of, or accompany the regular or irregular military forces of any foreign country or government when such forces are engaged in hostilities or in situations where imminent involvement in hostilities is clearly indicated by the circumstances;” as well as a list of any partner forces with which the United States has taken such actions. Critically, this provision requires the president to comply with these reporting requirements, which align with those under the WPR, any time U.S. armed forces are introduced into hostilities, or in situations where there is a clear risk of imminent involvement in hostilities. In short, Section 1285 simultaneously reinforces existing war powers reporting requirements and reestablishes that these requirements pertain to activities that consecutive administrations have attempted to place outside the bounds of the War Powers Resolution.

Although the NDAA is useful for playing small ball, it has certain limitations. Many of the amendments that lawmakers attempt to add to the NDAA do not make it in. A good number of those that do are stripped out during the conference process of merging the House and Senate provisions. It is not uncommon for an amendment requiring a tough vote to be adopted by one chamber with the knowledge that the other will kill it in conference, where the chairpersons and ranking members of the Armed Services Committees engage in intense horse trading. This appears more likely to occur when the chambers are politically divided and the amendment in question is notably controversial. For example, amendments to repeal the 2002 AUMF, preemptively constrain the president regarding the use of force against Iran, limit arms sales to Saudi Arabia, and prohibit various forms of support to the Saudi-led military campaign in Yemen all failed to make it through the conference process last year.

Lawmakers seeking to use the NDAA to advance a war powers agenda may also confront jurisdictional challenges. It is not necessarily healthy in the long run for U.S. foreign policy that the NDAA has become the vehicle for moving legislation that may fall outside the scope of the Armed Services Committees. Indeed, a fair amount of the provisions in Title XII—Matters Relating to Foreign Nations—implicate the Foreign Affairs and Foreign Relations committees, which have jurisdiction over war powers. Thus, there is a balance to be struck between moving war powers provisions and militarizing them through a vehicle used to authorize the Defense Department. Moreover, because the Armed Services Committees have the final say over the NDAA, they do the most to shape the provisions carried in it, rather than the Foreign Affairs and Foreign Relations committees. Ultimately, Congress will be best served either by finding a way to pass annually a State Authorization Act, or by creating a National Security Authorization Act that empowers the Departments of State and Defense and the Intelligence Community. In lieu of such unlikely action, NDAA is likely to remain a vehicle for moving legislation relating to war powers.

Courses of Action

The preceding sections outline the major issues and competing positions regarding the War Powers Resolution and updating the 2001 and 2002 AUMFs. This report also identifies alternative legislative routes to strengthening congressional war powers. It is almost impossible to contemplate the policy content of legislative action without also addressing the process and relevant politics, including questions about how Congress should prioritize and sync its efforts. This section lays out different courses of action (COAs) for how to pursue war powers reform, address the existing AUMFs, and use legislation to create political checks and advance oversight.

COA 1: Focus on using priority procedures and the NDAA to strengthen oversight, increase transparency, exert political influence, and build a foundation for future legislation to reform the War Powers Resolution and update the existing AUMFs.

This approach emphasizes small fixes to create legislative precedent through the use of repeated, low-cost legislative actions that could garner bipartisan support to shift norms. The aim is to create conditions for larger reforms to succeed in the future, by treating congressional war powers like a muscle that needs to be exercised in order to build strength for heavier lifts. The approach also allows for Congress to experiment with novel ways of influencing war powers issues. For example, operations conducted under the existing AUMFs are largely paid for using Overseas Contingency Operations (OCO)—a debt financing scheme that means taxpayers do not have to foot the bill. Lawmakers could attempt to end OCO financing, or use the NDAA to clarify when, if ever, debt financing would be acceptable for any military operation and require the president to publish an annual estimate of the amount of money spent on operations under the AUMFs. This is just one example of ways to improve transparency and potentially increase public support for reform.

This course of action has notable benefits: it provides lawmakers time to build consensus and flesh out thorny issues; avoids another dispiriting set of losses that destroys faith in the power of reform; and does not consume limited time and attention when lawmakers may need to be focused on other major initiatives. These benefits must be weighed against the limitations of such an approach. Incremental steps yield limited gains, and the longer Congress goes without reforming the WPR or updating the existing AUMFs, the more ground it stands to lose to the executive branch. Moreover, the wait for a propitious time for major legislative action could be interminable. Congress may find there is no time like the present.

COA 2: Continue using priority procedures and the NDAA to strengthen oversight, increase transparency, and exert political influence, while simultaneously introducing legislation to amend or replace the WPR.

This approach recognizes that although lawmakers can use various tools to shape the president’s behavior, political constraints are situational. The legal constraints envisioned by the Constitution are constant, and Congress will not be able to fulfill its constitutional duties until the WPR is amended or replaced. Even with the oversight mechanisms available to it and the NDAA as a vehicle for enhancing them, the level of congressional engagement the drafters intended does not occur, thereby narrowing opportunities for members to seek information from the executive branch, for civil society to engage in the political process, and for journalists to report on deliberations in ways that contribute to a more informed public.

This report identifies three key areas of focus for reform: hostilities, scope of mission and sunset provisions, and enforcement. Hostilities are the lynchpin. Without defining them, Congress will struggle to invoke, much less enforce the WPR. The AUMF debates have highlighted the need for new procedures governing whether, when, and how to expand the scope of future authorizations, as well as the importance of a provision requiring regular review and renewal. Enforcement is arguably the toughest challenge for legal and political reasons. Even if an enforcement mechanism is instituted, it will be difficult to wield if hostilities remain undefined and there are no guardrails on the scope of a mission. Yet the creation of a viable enforcement mechanism will also narrow the power differential between Congress and the president. There are other measures worth pursuing as well, and proponents of war powers reform should hold multiple hearings to inform draft legislation and lay the groundwork for a major legislative push.

The benefits of success would be far-reaching. Even success on one of the three fronts mentioned here could reshape power dynamics between the legislative and executive branches. Moreover, war powers reform would have longer-lasting effects than updates to the existing AUMFs, and could be less controversial. The process of addressing issues such as how to define hostilities or create mechanisms for expanding the scope of future authorizations also could inform follow-on attempts to update the existing AUMFs. It is possible that even an unsuccessful attempt at reform would have an effect on AUMF legislation and the use of the NDAA or other vehicles for smaller fixes. Conversely, it is unclear whether there is sufficient interest or consensus in Congress for a major war powers reform effort to succeed, and another failure, especially if the effort is premature, could further undermine future efforts. Moreover, while war powers reform likely would be more far-reaching than updating the existing AUMFs, it is also more theoretical. This could make it less controversial, but also less exciting for lawmakers looking for immediate impact.

COA 3: Continue using priority procedures and the NDAA to strengthen oversight, increase transparency, and exert political influence, while simultaneously introducing legislation to update the 2001 AUMF and revoke the 2002 AUMF.

This approach acknowledges that without updating, these authorizations will be strained to the point where they no longer have any legitimacy, a deleterious outcome for the legislative and executive branches. The benefits of success will depend on the contours of an update to the AUMF, although even a repeal of the 2002 AUMF would constitute progress. As with war powers reform, Congress should strongly consider a series of formal hearings to look deeply into the AUMFs and the conflicts they authorized, in this case along the lines of the Fulbright Hearings into the Vietnam War. This could help inform and galvanize support for a new AUMF.

First, an updated authorization should specify specific groups and/or countries and include a mechanism for adding new ones. As a compromise between ceding this to the executive and insisting on congressional approval in advance, Congress could authorize a listing system whereby the executive branch must meet certain specified criteria to add new groups under the AUMF and make additions subject to congressional review within a certain time period or on a quarterly basis.⁷⁵ Second, Congress should establish the upper limits, if any, of military force that could be used to address specific and discrete threats before the president has to return to Congress for additional authorization. Third, a new authorization should include a provision stipulating the need for review and renewal every three years, with a default sunset if Congress does not renew the authority.⁷⁶ Fourth, Congress should establish criteria defining when, if ever, the president is authorized by Congress, rather than as a function of Article II authority, to use military force in self-defense of U.S. troops, or when collective self-defense of partners is authorized against entities not covered under the AUMF, for the purpose of enabling efforts against entities that it does cover. Finally, Congress should codify the requirements created for the 2001 and 2002 AUMFs via the NDAA for any new AUMF.⁷⁷

Although there is widespread agreement on the flaws of the current AUMFs, the congressional politics have not changed considerably since recent efforts failed. There are no major indicators that progressives, moderate Democrats, and Republicans are ready to come together on the major issues that reform would entail. The risk also exists that a compromise measure would be so watered down that it does little to change the facts on the ground, and instead provides Congress with a rhetorical victory and a rationale to avoid further engagement on the issue.

COA 4: Continue using priority procedures and the NDAA to strengthen oversight, increase transparency, and exert political influence, while simultaneously introducing legislation to reform the War Powers Resolution, update the 2001 AUMF, and revoke the 2002 AUMF.

The assumption underlying this course of action is that war powers and AUMF reform are part of the same political conversation. AUMF debates have highlighted issues that war powers reform should consider, such as how to protect the scope of future authorized missions, concepts such as collective self-defense, and whether to include automatic sunsets. Similarly, the changing nature of warfare affects not only how a reformed WPR might define hostilities, but also the types of activities Congress may need to authorize for a new AUMF. Thus, a single piece of legislation could be the best method for advancing reform on both fronts. From a political and process perspective, it is also the case that moving two major bills on war powers and AUMF reform, respectively in the near- to medium-term, could be challenging. This approach at least provides the potential to address as many outstanding issues as possible at once, but it also comes with risks. Congress has been unable to pass either WPR or AUMF reform, and tying the two together could be overly complex. It is possible Congress only gets one swing at this, but equally plausible that tying the two together makes it more likely that Congress will swing and miss. Furthermore, this course of action treats war powers and AUMF reform equally, whereas such may not be the case in reality. Congress probably could jettison war powers reform along the way, but dropping AUMF reform might be more difficult once the two have been linked together. As a result, if AUMF reform dies, it could take down war powers reform with it.

Conclusion

Much of the discourse these days regarding the use of military force focuses on ending the “forever wars,” and the need for Congress to undertake AUMF reform. Yet, as this report illustrates, such reform is just one piece of a larger puzzle when it comes to regulating the use of force. Members of Congress and staffers should not consider the legislative options available to them in isolation of one another. They will need to take into account potential tradeoffs, but must also look for opportunities to stitch together different approaches in order to reclaim Article I authority. Perhaps most important, the small number of lawmakers and staff motivated by these issues will need to expand the community of interest that exists for exercising this authority if they have any hope of Congress playing the role envisioned for it in the Constitution.

About the Authors

Richard Fontaine is the Chief Executive Officer at the Center for a New American Security (CNAS). He served as President of CNAS from 2012 to 2019 and as Senior Advisor and Senior Fellow from 2009 to 2012. Prior to CNAS, he was Foreign Policy Advisor to Senator John McCain for more than five years. Fontaine also has worked at the State Department, on the National Security Council, and on the staff of the Senate Foreign Relations Committee.

Loren DeJonge Schulman is an Adjunct Senior Fellow and the former Deputy Director of Studies and Leon E. Panetta Senior Fellow at CNAS. Before joining CNAS, she served in senior staff positions in the White House National Security Council and the Department of Defense.

Dr. Stephen Tankel is an Associate Professor at American University and an Adjunct Senior Fellow at CNAS. He has served on the House Foreign Affairs Committee and in the Office of the Under Secretary of Defense for Policy. Tankel is the author of numerous works, including With Us and Against Us: How America’s Partners Help and Hinder the War on Terror.

Acknowledgments

The authors would like to thank Katie Galgano, Maura McCarthy, and Melody Cook for their invaluable work in bringing this report to life. They are grateful to Stephen Pomper, Mark Iozzi, Matt Duss, Daniel Schneiderman, Jessica Carroll, Mark Mitchell, Shannon Green, Alexis Arieff, Vance Serchuck, Melissa Dalton, Dan Mahanty, and many more for their insights and feedback throughout the project. This series of reports would not have been possible without the support of the Hewlett Foundation and Open Society Foundations.

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