The Cost of Conflation: Preserving the Dualism of Jus ad Bellum and Jus in Bello in the Contemporary Law of War.

In the first place, I want to express my thanks to the hosts of Opinio Juris and to the editors of the Yale Journal of International Law for the opportunity to discuss this piece in a public forum—and, above all, to Derek Jinks for kindly taking the time to read and comment on it. What animated this article is my sense that we have witnessed, and continue to witness, a largely tacit degradation in the vital axiom of international humanitarian law (IHL) that insists on the analytic independence of jus ad bellum and jus in bello, which, following Michael Walzer, I call the dualistic axiom. In short, that axiom says that in bello rules and principles apply equally to all belligerents, whatever each party’s ad bellum rationale for force (casus belli): be it, to cite the extremes, lawful self-defense or aggressive war in the service of a totalitarian ideology with genocidal designs. The axiom, as just war theorists have long recognized, therefore seems to produce counterintuitive results: as Thomas Hurka wrote, for example, “If military advantage justifies killing civilians, it does so only because of the further goods such advantage will lead to, and how much it justifies depends on what those good are.” So surely, he suggests, more collateral damage should be tolerated in a war against an enemy like Nazi Germany than in the Falklands War. Yet in law, in contradistinction to normative ethics, the injunctions of IHL would be far less effective, and in some cases might even cease to operate, were subjective, ideological, or politicized conceptions of the ad bellum justice or legality of each belligerent’s casus belli smuggled into IHL calculations. Scrutiny of jurisprudence and at least some state practice suggest, however, that such politicized appraisals of the legality or justice of particular conflicts have increasingly eroded the boundary between ad bellum and in bello constraints on war. They have also generated a related, widespread confusion in the application of proportionality, which has conceptually distinct ad bellum and in bello components that should be applied concurrently.

I offer three arguable examples of ad bellum-in bello conflation: the 1999 campaign against Kosovo; the thirty-four day war between Israel and Hezbollah in July 2006; and the resurrection of candidly justified torture in the “Global War on Terror.” What unites each, I suggest, is the often tacit view that ad bellum considerations may justifiably mitigate and perhaps even vitiate in bello constraints—including both context-dependent, flexible constraints such as the in bello principle of proportionality and absolute constraints such as the prohibition of torture or the denial of quarter. For example, the now infamous memorandum of Alberto R. Gonzales (actually, David Addington), asserting that “the war against terrorism is a new kind of war,” which “renders obsolete Geneva’s strict limitations on question of enemy prisoners and renders quaint some of its provisions,” may be understood as a suggestion that ad bellum considerations should justifiably relax, or even vitiate, what some see as anachronistic in bello constraints.

I trace the theoretical source of ad bellum-in bello conflation to familiar twenty-first century themes including the rise of transnational terrorist networks, asymmetrical warfare, geopolitical reconfiguration, and technological progress, as well as to the demise of the dualistic axiom’s traditional rationales: one theological, the other (broadly speaking) positivist. Early just war theorists espoused “probabilism,” the view that all belligerents in war should practice moderation because of epistemic uncertainty about which side fought on the side of divine justice. And in the nineteenth century, the high watermark of legal positivism, international law abandoned even the pretense of a genuine jus ad bellum. This rendered the idea of conditioning the legality of particular means and methods of warfare on a non-existent body of law simply incoherent. But with the reintroduction of a positive jus ad bellum in the postwar era, some scholars openly suggested that the dualistic axiom should indeed be abandoned, lest the Charter regime’s perceived authority suffer, or the elaboration of a new body of IHL rules and principles interfere with the postwar aspiration to abolish war for all time. Yet quickly, as early as 1953, Sir Hersch Lauterpacht recognized that the Charter regime, whatever the hopes of its drafters, would often prove quixotic and therefore that abandoning the dualistic axiom might well lead, in practice, to the demise of IHL, which would “cease to operate if [its rules] were made dependent upon the legality of the war on the part of one belligerent or group of belligerents.” International lawyers, almost without dissent, have since adopted Lauterpacht’s view and nominally affirm the dualistic axiom. But at least three trends, I think, have led to the subtle (and sometimes overt) degradation of the axiom in the actual practice of warfare: (1) an aggressor-defender model of war, whereby one belligerent implicitly denies the dualistic axiom by reference to the maxim ex injuria jus non oritur (a right may not arise from an illegal act), e.g., North Vietnam’s position in the Vietnam War; (2) the conceptual collapse of ad bellum and in bello proportionality, i.e., in effect, the confusion of architectural military objectives with the “concrete and direct military advantage anticipated,” which should be the focus of IHL (a phenomenon evident, for example, in the thirty-four day war between Israel and Hezbollah in 2006 and, more recently, in the tragic conflict in Gaza); and (3) “supreme emergency” arguments, which the ICJ arguably endorsed in Nuclear Weapons, and which underlie, for example, the hackneyed ticking time-bomb torture scenario.

Furthermore, while I lack adequate space here to summarize my critique of the ICJ’s jurisprudence of war, I suggest that the ICJ has done a disservice to IHL by adhering to a contrived (and now dated) view of the Charter’s ad bellum framework (supposedly identical to that of customary international law). It first set out this view in Nicaragua and, to the dismay of many, unreflectively affirmed it more recently in the wholly incongruous context of a virtual world war between states and non-state belligerents fighting in central Africa (Armed Activities on the Territory of the Congo). In effect, the Court has thereby avoided opining on the truly difficult and critical questions of ad bellum and in bello necessity and proportionality in the context of non-traditional warfare by focusing, instead, quite narrowly on an anachronistic vision of self-defense. It has also tended to disregard the dualistic axiom’s insistence that ad bellum analysis does not obviate the need to analyze ad bellum proportionality and the full corpus of the jus in bello.

The dualistic axiom is indispensable to the efficacy of the law of war, such as it may be, because it theoretically ensures that relatively common, if debatable, ad bellum violations do not obviate or diminish the humanitarian potential of jus in bello, modern IHL. Just war theorists, such as Jeff McMahan and Thomas Hurka, have done a superlative job analyzing the normative ethical foundations of the axiom and exposing its theoretical weaknesses. International law, I believe, ignores their analyses at its peril. Yet while such challenges to the dualistic axiom do not prove unassailable even in theory, in the final analysis, I suggest that the dualistic axiom, as a legal principle, remains firmly rooted in experience and an appreciation of the political and moral reality of war—more, to adapt Justice Holmes’s maxim, in experience than in logic. So the dualistic axiom should candidly confront serious objections raised by recent theorists. At the same time, for the axiom to operate most effectively, it must adapt to new geostrategic developments, technological advances, and changes in the nature of warfare. The article concludes by clarifying how the axiom might be conceived and applied today to best serve the values and policies that underwrite it. In particular, I suggest that the axiom, despite both theoretical and practical difficulties at the margins, must be preserved rigorously and self-consciously; that ad bellum and in bello proportionality should be clarified and applied concurrently with greater precision; and that international lawyers should consider whether the values that underwrite a “humanized” IHL and international human rights law alike should ever countenance limited exceptions to the axiom (e.g., in cases of humanitarian intervention or “transformative occupation”). Above all, my hope is that the article, for all its flaws, will help to revive a dialogue about the appropriate relationship between the traditional branches of the law of war in the twenty-first century—for these issues have been conspicuously (and, I think, dangerously) absent from that dialogue.