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Use of Force Against Terrorist Groups: The Perils of Conflating Means and Ends

September 28, 2016

Transnational terrorist groups, from al Qaeda to the Islamic State, complicate this framework in numerous ways, in no small part by making it difficult to ascertain when and where armed conflict exists such that wartime targeting and detention rules apply.

International law simultaneously erects a presumption against the right to initiate force and in favor of the right to wield force effectively. This bifurcation is central to the laws governing warfare, which neither privilege fighters whose cause is just, nor penalize those whose regime is ignoble.


The distinction between jus ad bellum, or law governing the resort to force by states, and jus in bello, or law governing the conduct of hostilities, is rooted in the problem of law avoidance. The adoption in the 1949 Geneva Conventions of objective criteria for determining when an armed conflict exists—thereby triggering jus in bello—was intended to deprive warring parties “of the pretexts they might in theory invoke for evasion of their obligations.” The 1977 additional Protocols to the Geneva Conventions reaffirmed the applicability of the signatories’ humanitarian responsibilities, “without any adverse distinction based on the nature or origin of the armed conflict or on the causes espoused by or attributed to the parties to the conflict.”


Given that ongoing hostilities are a good indication of differences of opinion, it was ineffective to tie the law’s urgently needed humanitarian protections to agreement over a war’s underlying legality. Moreover, since the troops engaged in combat—many of whom have historically been conscripts—are instruments rather than makers of state policy, it was both unfair and unworkable to calibrate their status based on their leaders’ moral worth.


As such, the law of war adopts a “posture of startling moral modesty,” wherein soldiers of sovereign states are vested with the same privileges and obligations irrespective of the casus belli. Whether the battlefield rules apply is a purely descriptive matter, remaining neutral as to whether the reason for war was valid or which side (if any) is right. The philosopher Michael Walzer calls this concept “the moral equality of soldiers”; legal scholars refer to it as the principle of equal application.


Even in armed conflicts against non-state actors, in which the right of enemy fighters to take up arms may be contested, the mandate to comply with the dictates of jus in bello is not predicated on reciprocity, nor are violations excused by the other side’s transgressions. The law of war does not permit derogation because it defines a code of conduct specifically applicable in conflict. To say that war exists, and that wartime principles are the prism through which fighters’ conduct will be judged, is not to endorse or justify the resort to arms, but rather to invoke the specialized protections necessary to mitigate war’s worst horrors.


Transnational terrorist groups, from al Qaeda to the Islamic State, complicate this framework in numerous ways, in no small part by making it difficult to ascertain when and where armed conflict exists such that wartime targeting and detention rules apply. The Bush administration, at least in the immediate aftermath of September 11, 2001, posited that some of the law’s humanitarian protections were inapplicable to the War or Terror, and were, in any event, rendered “obsolete” and “quaint” by modern challenges. This position was anathema to the U.S. military, which had long maintained a policy of compliance with law of war principles across the conflict spectrum and regardless of conflict classification (and trained its personnel accordingly). Ultimately, the U.S. Supreme Court rejected the government’s view.


The Obama administration, far from abandoning the war paradigm of its predecessor, dramatically expanded the scope of targeted killing operations, both on and off “hot battlefields.” Top officials pledged fealty to “all applicable law, including the laws of war,” but ran headlong into the problem that had vexed the effort to apply a wartime framework to the terrorist threat in the first place: namely, the rules of warfare only apply when and where an armed conflict is, in fact, ongoing.


To square this circle, the Obama administration proposed that the jus ad bellum right of states to act in self-defense could simultaneously regulate the use of force without the need to consult the rules of jus in bello or determine whether they are triggered. This theory, sometimes referred to as “self-defense targeting” or “naked self-defense,” was notably articulated by the State Department Legal Adviser’s justification of lethal strikes by states “engaged in an armed conflict or in legitimate self-defense.” It rests on the presumption that when a state is entitled to resort to self-defense under customary international law and Article 51 of the United Nations Charter, the jus ad bellum principles that condone the initiation of hostilities are also sufficient to govern how they are conducted.


As scholars have noted, this deliberate conflation of disparate legal doctrines “reflects an unlawful and disturbing tendency” to entangle the justice of a state’s cause with its methods of war. The problem with this approach—as Bob Dylan aptly captured in his 1964 protest song, “With God On Our Side”—is that all sides to a conflict are likely to perceive themselves as in the right, and thereby entitled to take liberties with the rules. The innovation at the heart of the law of war is that it divorces means and ends. A just cause is no license to commit war crimes. This distinction is what enables compliance and ensures accountability. The battlefield rules stand for the notion that we can still make judgments about right and wrong behavior even, or perhaps especially, in war.


Although ad bellum and in bello principles overlap in nomenclature, they have vastly different meanings owing to their divergent perspectives. The concepts of necessity and proportionality in the jus ad bellum context are intended to preserve the norm of peaceful dispute resolution and make war the exception, rather than the rule. Thus, necessity means that force must be a truly last resort, whereas proportionality means that it must be limited to countering the imminent threat.


In contrast, the jus in bello principles assume a backdrop in which violence has already commenced. Here, lethal force may be wielded against lawful targets as matter of first resort. In this context, necessity refers to targeting military objectives only, while proportionality signifies the obligation to mitigate (although not entirely eliminate) collateral damage. These fundamentally incompatible perspectives reflect the disparity between preventing war and regulating it. Indeed, self-defense is an entirely ad bellum concept, with no place in the in bello regime.


As the events of this summer revealed, however, the Obama administration continues to maintain that “national self-defense” is a standalone legal paradigm for conducting military operations, even as it prepares to hand the reins of its counterterrorism architecture to a successor. The Executive Order on combat operations issued in July refers to “the use of force in armed conflict or in the exercise of the nation’s inherent right of self-defense.” The Presidential Policy Guidance on direct action against terrorist targets—released in August under the pressure of litigation by the American Civil Liberties Union—distinguishes between individuals who are targetable in armed conflict or “in the exercise of national self-defense.”


Yet as Sir Daniel Bethlehem has noted, the principles addressing “the threshold for the use of armed force in self-defense” can neither displace nor preempt the principles governing how force is used. Rather, “any use of force in self-defense would be subject to applicable jus in bello principles governing the conduct of military operations.” Simply put, as a nation engaged in the long and hard task of countering terrorist threats, we cannot eschew the hard work of determining when and where armed conflict exists, and which legal regime applies. A legal basis for using force is not synonymous with a legal framework for employing it.




Major Charlie Kels is a judge advocate in the U.S. Air Force Reserve, senior attorney at the American Medical Association, and formerly an attorney for the U.S. Department of Homeland Security. His writings on the law of war have appeared in the National Interest, the Journal of Military Ethics, the Harvard National Security Journal, the National Law Journal, Armed Forces Journal, and the Hill. His views do not reflect those of the U.S. government or AMA.