Brian Cox on “Al-Zawahiri Strike, Article 51 Self-Defense, and Future Implications for the AUMF”

Today’s post is the second installment of Lawfire’s^® mini-series about the airstrike that killed Ayman al-Zawahiri.  In yesterday’s post, I gave you some “shortbursts” on my view of a number of legal issues raised by the strike, but today’s essay by Brian Lee Cox gives you another perspective by providing you with a ‘deep dive’ into several key matters.  I think you will find his views thoughtful, scholarly, and provocative!  

Al-Zawahiri Strike, Article 51 Self-Defense, and Future Implications for the AUMF

by Brian Lee Cox

President Joe Biden addressed the Nation Monday night to deliver remarks regarding a “successful counterterrorism operation” that killed the leader of al-Qaeda, Ayman al-Zawahiri, two days earlier, on July 30, 2022. According to information provided to the media by a senior administration official, the drone strike killed al-Zawahiri while he stood on the balcony of a Haqqani safehouse in Kabul, Afghanistan as his family members – none of whom were reportedly injured – were in different rooms of the residence.

Although President Biden did not articulate the domestic or international legal basis for the attack, he did reiterate during his address a promise he made after withdrawing all ground troops from Afghanistan that America “will continue to conduct effective counterterrorism operations in Afghanistan and beyond” even though U.S. troops are no longer present in the country.

Considering that a spokesperson announced that the de facto Taliban government “strongly condemns this attack on any pretext and calls it a clear violation of international principles and the Doha Agreement,” it can be assumed that the consent of host nation does not constitute a potential international legal basis for the attack. Likewise, no current UN Security Council resolution exists that would permit the attack pursuant to Article 42 of the UN Charter.

This leaves self-defense pursuant to Article 51 of the Charter as the sole possible international legal basis for the strike according to the prevailing interpretation of the contemporary use of force construct.

From the perspective of domestic law, it is possible that the administration will seek to justify the strike pursuant to legislation adopted by Congress a week after 9/11 purporting to “authorize” the President “to use all necessary and appropriate force against those…persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001.” This “Authorization for Use of Military Force” (AUMF) has been cited by the administrations of Presidents Bush (43), Obama, and Trump as at least partial justification for various combat operations abroad in the wake of 9/11.

As these linked sources indicate, all three administrations have also referred to authority conferred by Article II of the U.S. Constitution. President Biden has also invoked Art. II “constitutional authority to conduct United States foreign relations and as Commander in Chief and Chief Executive” as a domestic legal basis for geographically and temporally limited attacks since early in his administration.

As a complement to Maj. Gen. (ret.) Charlie Dunlap’s insightful overview of some of the most salient legal issues implicated by the attack, this present post engages in a deep dive of a number of factors that are often hotly debated following what is widely referred to as a “targeted killing” such as the attack on Ayman al-Zawahiri.

After framing the analysis by describing the contours of several unsettled issues in international and U.S. domestic law, controversies related to the international legal basis for the attack are addressed. An analysis of the domestic legal basis and the related perennial challenge of determining the precise balance of constitutional authority between the legislative and executive branches follows the assessment of international law, and then the essay closes with some concluding reflections to situate the substantive subjects addressed below in the broader context of contemporary public discourse and pending congressional legislation.

International Legal Issues Routinely Raised

The attack against Ayman al-Zawahiri will almost certainly spark discussions the contours of which have become rather familiar since the 9/11 attacks more than two decades ago.

Given that Article 51 of the UN Charter textually permits the use of force in self-defense only “if an armed attack occurs against” a Member State (emphasis added), how can the Biden administration rely on Article 51 of the Charter as the sole international legal basis for the strike? Although al-Qaeda has been attempting to or successfully conducting “armed attacks” against the United States since at least the 1993 World Trade Center bombing, there is no indication that al-Zawahiri directly posed an imminent threat against the United States at the time of the strike, which would arguably permit the engagement pursuant to the Caroline doctrine.

Some observers have questioned whether the self-defense provision reflected in Article 51 of the Charter can be utilized as a justification for the use of force against a non-state actor in the territory of another State at all absent host nation consent or Security Council approval.

A number of States have reportedly either explicitly or implicitly endorsed the so-called “unable or unwilling” doctrine pursuant to which a “territorial State is unable or unwilling to confront effectively a non-State actor in its territory so that it is necessary to act in self-defense against the non-State actor in that State’s territory without its consent.” Meanwhile, a number of observers have criticized the legitimacy of the doctrine.

Even if the unable or unwilling doctrine is accepted as legitimate for the sake of argument, it seems rather difficult to describe a drone strike against a presumably unarmed person as he stands on the balcony of a house located in a metropolitan area such as Kabul where there are no active hostilities and in a country where no American troops are present as an act of “self-defense.”

If al-Zawahiri did not himself constitute an “imminent” threat against United States persons or vital property at the time of the strike such that the Caroline doctrine might apply, there was arguably no overt act for which the government could claim the necessity to attack in self-defense, which is a threshold requirement for the unable or unwilling test to apply even if the doctrine is indeed accepted as legitimate.

In the absence of the consent of host nation or a relevant Security Council resolution, self-defense pursuant to Article 51 is the only possible international legal basis for the attack pursuant to the prevailing interpretation of the contemporary use of force model. If the attack does not qualify as self-defense, then, there is potentially no legal basis in international law for the attack according to the prevailing understanding, regardless of whether the unable or unwilling doctrine applies.

Domestic Legal Basis and the AUMF

Turning to the potential domestic legal basis, relying on legislation passed in the immediate aftermath of 9/11 is increasingly tenuous now more than two decades removed from the catastrophic terrorist attack. That would leave only Article II authority, but the arguably questionable international legal basis potentially casts doubt on whether an attack such as the al-Zawahiri strike qualifies as a legitimate act of foreign relations.

Since the al-Zawahiri strike is the first publicly-acknowledged use of force by the U.S. government in Afghanistan since nearly a year ago when the last American troops left the country, this attack will undoubtedly feature prominently in long-running debates regarding the way ahead for the 2001 and 2002 congressional “authorizations” to use military force.

Among the most recent suggestions in AUMF scholarship is a Just Security article in which co-editor-in-chief Dr. Tess Bridgeman conveys support for a pending legislative provision that would express the “sense of Congress” that any new AUMF should include a “date on which the authorization is terminated unless reauthorized by Congress, a.k.a. a sunset.”

The actual pending legislation presents two operative provisions that would express the “sense of Congress.”

First, “inclusion of a sunset provision or reauthorization requirement in authorizations for use of military force is critical to ensuring Congress’s exercise of its constitutional duty to declare war.” (emphasis added)

Second, “any joint resolution enacted to authorize the introduction of United States forces into hostilities or into situations where there is a serious risk of hostilities should include a sunset provision setting forth a date certain for the termination of the authorization for the use of such forces absent the enactment of a subsequent specific statutory authorization for such use of the United States forces.” (emphasis added)

Although the draft legislation expresses that “legal experts who have served in both Democratic and Republic administrations recommend the inclusion of a sunset clause” for future “authorizations” to use military force, the terms I have emphasized above raise significant constitutional concerns related to congressional authority to impose such a requirement.

Domestic Legal Basis and “War in a Constitutional Sense”

While the Constitution vests authority to declare war exclusively in Congress, the “constitutional duty to declare war” is not the same as legislative “authorizations for use of military force.”

As I describe here on Lawfire while analyzing the domestic legal authority to implement a no-fly zone over Ukraine, “as long as the intervention does not constitute war in the constitutional sense, the decision – and the ultimate responsibility for that decision – must rest with just one person, not with 535 plus one.”

After surveying the “broad and deep historical roots” of “unilateral executive authority to employ force in situations short of war,” in that essay I emphasize the “vital importance of distinguishing a ‘war’ requiring a congressional declaration from the more general category of employing military force in armed conflict abroad.”

The implications of the al-Zawahiri strike on the continued viability of the 2001 AUMF and the pending legislation involving congressional “authorizations” to use military force in general likewise demonstrate the “vital importance” of distinguishing “war in a constitutional sense” that would require Article I authorization from other military interventions that do not.

The same is true for the “authorization” to introduce “United States forces into hostilities or into situations where there is a serious risk of hostilities.” This provision invokes the War Powers Resolution (WPR) – legislation adopted in 1973 purporting to require the executive to “terminate any use of United States Armed Forces” within 60 days after introducing U.S. forces “into hostilities or into situations where imminent involvement in hostilities is clearly indicated by the circumstances” unless Congress declares war or grants an extension.

Although the WPR was adopted nearly five decades ago, a report by the Congressional Research Service succinctly notes that “[e]very President since the enactment of the War Powers Resolution has taken the position that it is an unconstitutional infringement on” executive authority. This questionable constitutional foundation of the WPR casts doubt on the legitimacy of a proposed AUMF sunset clause that would establish “a date certain for the termination of” such an “authorization” following the introduction by the executive of U.S. forces into actual or imminent hostilities.

If the WPR itself represents an infringement upon the constitutional authority of the commander-in-chief of the armed forces, a sunset clause purporting to terminate an AUMF on a date certain upon the same conditions established in the WPR would be unconstitutional on the same grounds. Congress alone has the authority to declare war, but actual or imminent hostilities that do not qualify as “war in the constitutional sense” do not require a declaration of war and, as such, are beyond the scope of this enumerated constitutional authority that is unquestionably vested in Congress.

With some enduring challenges related to the international and domestic legal basis for so-called “over the horizon” strikes like the attack on al-Zawahiri thus in focus, I turn now to present suggestions for revising contemporary discourse to more effectively address current and emerging challenges related to the transnational use of force. The suggestions address discourse involving the international legal basis for “over the horizon” strikes first before then considering the domestic legal basis.

Reframing the Prevailing Interpretation of the Standard Use of Force Model

Standard discourse that engages with international law involving the use of force can be depicted as a debate between what Professor Matthew Waxman has described as the “Bright-Liner” and “Balancer” perspectives.

As Prof. Waxman explains, “‘Bright-Liners’ generally favour governing states’ legal authority to use force unilaterally by clear and rigid rules that admit little case by case discretion.” In contrast, “‘Balancers’ generally believe that the legality of unilateral resort to force should be judged by objective but flexible standards that call for weighing contextual factors, thereby vesting in states some discretion to account for competing values.”

A sampling of the discourse that emerged after the attack by U.S. forces that killed General Qassem Soleimani in Iraq in January 2020 provides a practical illustration of the discord between the two camps.

In making the case that the strike was “lawful self-defense, not ‘assassination,’” Maj. Gen. (ret.) Charlie Dunlap presents an analysis that aligns well with Waxman’s description of the Balancer perspective. In contrast, Professor Adil Haque presents an analysis that aligns with the Bright-Liner perspective in offering a critical assessment of the U.S. justification for the attack.

Whether Bright-Liner or Balancer, these competing perspectives share at least one commonality: both are centered on the text of the UN Charter. My initial suggestion for revising contemporary discourse involving the transnational use of force is to depart from the text of the Charter – here, from Article 51 in particular – when an attack is directed against a non-state actor rather than an agent of a Member State.

The “Risk of Obsolescence” of the UN Charter Jus Ad Bellum Construct

This is a suggestion I present in an article that was published last November in the Canadian Yearbook of International Law. In contrast to the general Balancer and Bright-Liner approaches that are prevalent in contemporary discourse, there I suggest a “Reframer” approach that would only apply the text of the Charter in the context of an international, rather than transnational, actual or contemplated use of force.

Applied to the al-Zawahiri strike, the “Reframer” approach would not refer to the text of the Charter – specifically to Article 51 – to determine whether the attack complies with international law. Afghanistan and the United States of America are both Member States of the United Nations, but al-Qaeda is not.

While it is true that the Charter requires Member States to endeavor to “settle their international disputes by peaceful means in such a manner that international peace and security, and justice, are not endangered” (emphasis added), an attack directed against the leader of an organized armed group does not directly involve relations between Afghanistan and the United States simply because the target is located on the territory of Afghanistan.

Reframing the analysis in this manner would further require a more nuanced assessment of the purpose of and justification for national sovereignty that receives textual assurance from the cornerstone of the UN Charter, Article 2(4). The “Purposes and Principles” model I begin to develop in the “Risk of Obsolescence” article represents an essential first step in developing a more nuanced application of state sovereignty.

In short, I suggest in the article that a more comprehensive assessment of values described in Chapter I – “Purposes and Principles” – of the UN Charter should be considered when analyzing an actual or contemplated use of force that is directed against a member of an organized armed group located in the territory of a host nation to determine the impact, if any, on the supreme value of self-determination that is exercised by the Peoples within the relevant territorial boundary.

Along with reframing the analysis to consider compliance with customary international law rather than the text of the Charter when an attack is directed against a member of an organized armed group rather than an agent of a Member State of the United Nations, my second suggestion for enhancing the effectiveness of contemporary discourse is to more accurately determine whether such an attack should actually be described as a use of force in “self-defense” at all.

Enduring Transnational Armed Conflict and Article 51 “Self-Defense”

Although the “reframing” suggestion frees the analysis from the textual confines of the UN Charter when engaging with a transnational, rather than international, use of force, the second suggestion involves eschewing the purported requirement to comply with the self-defense provision of Article 51 of the Charter in the first instance.

To lend practical context to the conceptual analysis, it may be useful to compare the ongoing hostilities between al-Qaeda and the United States to the campaign to liberate Kuwait following the invasion by Iraq in 1990.

There is no question that Kuwait retained a legitimate claim to self-defense in response to an armed attack. By extension, collective self-defense was permissible even before the Security Council adopted Resolution 678, which authorized Member States to use “all necessary means to…to restore International peace and security” unless Iraq voluntarily withdrew from Kuwait by January 15, 1991.

After Iraq invaded Kuwait on August 2, 1990, active hostilities remained ongoing until Iraq was forced to withdraw and accept the terms of a ceasefire established in Security Council Resolution 686 on March 2, 1991. Although Kuwait retained the inherent right to use force in self-defense pursuant to Article 51 of the Charter for the period of six months from invasion to ceasefire from a jus ad bellum perspective, any specific use of force at the tactical or operational level from a jus in bello perspective did not have to be characterized as “self-defense” at all.

That is, after the hostilities in Kuwait were initiated by Iraq, the campaign to dislodge Iraqi forces from Kuwait was for the purpose of defending and restoring Kuwaiti sovereignty. However, an individual attack by, say, a U.S. Air Force F-111 fighter jet engaged in what came to be known as “tank plinking” against an Iraqi T-72 did not necessarily have to constitute “self-defense” in response to an “imminent” threat against coalition forces.

As long as such a strike complied with relevant rules of the law of armed conflict, it did not necessarily need to be justified as a self-defense engagement even though the intent of the campaign was to “defend” Kuwait.

While this analysis and the application of the underlying legal framework is fairly straightforward, the conceptual foundation becomes distorted when converting the text of the Charter to the context of a transnational use of force against members of an organized armed group.

In the context of the al-Zawahiri strike, if it seems rather misleading to characterize the attack as a use of force in “self-defense” in response to an “imminent attack” by al-Qaeda, that is because it is misleading. This is because an attack against members of a reportedly adversarial non-state armed group with which the United States remains engaged in ongoing hostilities is no more an act of “self-defense” than was an F-111 engaged in tank plinking after hostilities were initiated by Iraq in the Gulf War.

Instead of relying on the “inherent right of self-defense” text of Article 51 of the Charter, which arguably does not apply in the first instance if the use of force construct is reframed since transnational rather than international relations are involved, States should refrain from describing as “self-defense” an attack against a member of an organized armed group, such as al-Qaeda in this case, with which the State remains engaged in ongoing hostilities.

Domestic Legal Basis and Implications for the AUMF

With suggestions related to reframing the discussion of the international legal basis for “over the horizon” attacks such as the al-Zawahiri strike thus described, the analysis turns now to assess the domestic legal basis. The starting point for the domestic law discussion begins with a “listing of notable deployments of U.S. military forces overseas from 1798-February 2022” published in a recent Congressional Research Service report.

Of these hundreds of listed examples that span a period of over two centuries, Congress has formally declared war on only 11 occasions, which collectively involve only 5 armed conflicts. From 1798 to 2002, there have been only 12 “key statutory authorizations for the use of military force.” With hundreds of specific examples of the use of military force since the Founding but only 23 total declarations of war or key statutory “authorizations” to use force, the independent Article II constitutional authority of the commander in chief must be rather robust.

If a congressional “authorization” to use force is not an absolute requirement when a military involvement does not amount to “war in a constitutional sense,” what, then, is the value of the congressional legislation?

The short answer is that an AUMF is nothing more than a political declaration of support for a contemplated or ongoing use of force by the executive. To describe why that is, it is useful to recall the famous tripartite description of the balance of power between the executive and legislative branches presented by Justice Robert Jackson in the Youngstown Sheet & Tube Supreme Court decision of 1952.

Justice Jackson on Maximum Power, Zone of Twilight, and the Lowest Ebb

In Justice Jackson’s concurring opinion, he describes three distinct categories of executive power vis-à-vis the legislature. Jackson described the first category by observing, “When the President acts pursuant to an express or implied authorization of Congress, his authority is at its maximum, for it includes all that he possesses in his own right plus all that Congress can delegate.”

For the second category, when Congress is silent on a matter, Jackson describes that “there is a zone of twilight in which he and Congress may have concurrent authority, or in which its distribution is uncertain.”

Finally, for the third category, Jackson explains that when the “President takes measures incompatible with the expressed or implied will of Congress, his power is at its lowest ebb, for then he can rely only upon his own constitutional powers minus any constitutional powers of Congress over the matter.”

In the context of the 2001 AUMF, there is no question that President Bush exercised executive authority at its maximum in October 2001 when attacks by the U.S.-led coalition commenced in Afghanistan.

The AUMF joint resolution had been adopted less than a month earlier by a vote of 98-0 in the Senate and 420-1 in the House. The president exercised his independent Article II constitutional power to order the armed intervention in Afghanistan, while Congress utilized enumerated Article I legislative power to “authorize” the use of military force.

Up until now, each time I have described this congressional legislative power, I have included quotation marks around “authorize.” This is a deliberate detail, as the executive possesses independent constitutional power even in the absence of an “authorization” from Congress. Without an AUMF, the president functions in a “zone of twilight” as Justice Jackson describes.

Even if Congress were to adopt legislation over the president’s veto purporting to prohibit the unilateral use of force by the executive, the commander in chief would still not be entirely barred from doing so. Rather, such an action would be at the “lowest ebb” of the president’s independent constitutional authority.

Surely there would be a political price to pay for using force against an unambiguous expression of congressional disapproval. However, the contemplated action would nonetheless be constitutional and, therefore, lawful.

Given the passage of time and the growing discontent with so-called “zombie authorizations,” it is unlikely that the 2001 AUMF still represents executive power vis-à-vis Congress at its maximum. However, since the legislation does not constitutionally constitute a congressional “authorization” to use military force, Congress would do well to simply repeal all existing AUMFs and replace them with…nothing.

The executive will continue to use force as the president deems necessary, while true “accountability” will continue to be applied where it should be – at the ballot box every four years. If Congress can muster sufficient political consensus to refuse requests by the executive to authorize appropriations for particular military interventions or operations, the legislature would be exercising the other primary enumerated constitutional power in the current context aside from declaring “war” – the power of the purse.

Concluding Reflections

The recent attack on Ayman al-Zawahiri in Kabul will quite likely reignite a debate that has become all too familiar in the post-9/11 era. While President Biden reaffirmed the commitment to continue conducting “effective counterterrorism operations in Afghanistan and beyond,” the international and domestic legal basis for doing so will undoubtedly remain hotly contested.

The familiar debate between Balancers and Bright-Liners, to borrow again from Professor Waxman’s portrayal, may yet unfold again – with much the same result. Those of the Balancer persuasion will find the attack to be a lawful exercise of national self-defense pursuant to Article 51 of the UN Charter, while the Bright-Liner camp will denounce the strike for failing to comply with the “armed attack” requirement established in the text of Article 51.

Familiar though the debate may be, the enduring discord manifests latent limitations inherent in the prevailing penchant for UN Charter formalism.

The time may be ripe – if not now, then perhaps after the next similar high-profile use of transnational force, or the next – to step beyond the text of the Charter to more fully explore the vast uncharted territory of customary law. That is, to reframe the assessment beyond the conventional text of the venerable Charter of the United Nations.

If we – as a community of expert practitioners, scholars, and advocates – do accept, even for the sake of argument, that the unwilling or unable doctrine is a contemporary component of customary law, by exploring the contours of the doctrine in depth we may well identify vital factors that separate “unwilling” from “unable” – even though they are both utilized essentially interchangeably to describe the single doctrine.

There must be something about the comparative infringement of sovereignty that separates the exceptionally volatile reaction among the populace in Iraq after the attack against Qassem Soleimani at the Baghdad International Airport in 2020, for example, from the seemingly rather more subdued response in Syria and beyond to the attack on Iran-backed militias operating on the frontier just beyond the Syria-Iraq border a month or so into President Biden’s term of office.

The latter attack was likely comparatively closer to the “unable” end of the spectrum, while the former closer to the “unwilling” side given the location of both uses of force. The endeavor to chart the potentially meaningful differences between such attacks is effectively stunted by the prevailing resolute reliance on the text of the UN Charter, in particular in this case on Article 51 thereof.

On the domestic front, the path to more productive discussions and debate begins with an honest assessment of what constitutes “war in the constitutional sense” and, as importantly, what does not. The former directly implicates the enumerated constitutional authority of Congress to declare war. The latter is almost certainly the exclusive domain of the executive pursuant to Article II of the Constitution.

While it is understandable for the legislature to strive to manufacture pathways to a more assertive role in important matters such as the extraterritorial use of armed force, the 435 individual interests represented in one chamber and the 100 interests in the other combine to make building consensus ever more challenging in the polarized political climate of today. Passing legislation is incredibly difficult, just as the Framers intended.

The existing paralysis-without-sufficient-consensus environment is suitable for a legislative role, but it is costly in the field of foreign policy.

Congress is, to be quite candid, not competent to decide whether or for how long the United States government should be permitted to engage in attacks such as the strike against the leader of al-Qaeda that took place a few short days ago. Whatever the precise contours of “war in the constitutional sense” may be, an attack of this nature most certainly does not qualify.

If it makes sense as a matter of legislative hygiene to repeal what amounts to a political statement of support that was adopted a week after the 9/11 attack more than two decades ago, Congress should unite behind a joint resolution to do so. It is an act of extreme political cowardice to instead attach what amounts to a rider to the must-pass annual National Defense Authorization Act, as the movement currently afoot seeks to do.

Regardless of the fate of the 2001 AUMF and the even less relevant 2002 legislation, the Biden administration must vigorously challenge efforts by the legislature to encroach upon existing constitutional executive authority. Continuity of purpose and clarity of effort in protecting America’s interests in foreign relations and national security demand nothing less, as the decisive attack against the leader of al-Qaeda a few short days ago demonstrates yet again.

About the author: 

Brian L. Cox is a doctoral candidate lecturer and J.S.D. candidate at Cornell Law School and a visiting scholar at Queen’s Law in Ontario. Brian retired in 2018 from the U.S. Army after 22 years of military service. He served as an airborne infantry soldier, combat camera operator, airborne infantry officer, and for seven years as a military legal advisor. His combat deployments include Iraq from 2003-2004 as a combat camera operator and Afghanistan from 2013-2014 as the chief of international and operational law for Regional Command-East in Afghanistan.

Brian also served as a military prosecutor, federal prosecutor, brigade judge advocate, and military magistrate while he was a military legal advisor. His military awards, decorations, and qualifications include the Ranger Tab, Senior Parachutist Badge, Pathfinder Badge, Air Assault Badge, Bronze Star Medal, Meritorious Service Medal, Basic and Advanced Collateral Damage Estimation Certification, Joint Firepower Certification, and Special Victim Unit Investigator Certification. Brian holds an LL.M. from Queen’s Law and a B.A. (International Relations) and J.D. from the University of North Carolina.

The views expressed by guest authors do not necessarily reflect the views of the Center on Law, Ethics and National Security, or Duke University (see also here).

Remember what we like to say on Lawfire^®: gather the facts, examine the law, evaluate the arguments – and then decide for yourself!