5 Jus Post Bellum and Proportionality Michael A. Newton* I. Introduction This chapter proceeds from the premise that the proportionality principle as applied in its respective legal usages before the onset of armed conflict (embedded within the jus ad bellum framework) and during armed conflict (jus in bello), cannot and should not be dis- aggregated from the larger question of the desirability of justice following conflict (jus post bellum). Ours is the ‘era of proportionality’ in the sense that the proportionality principle is a ‘legal construction’ that is an integral aspect of legal and moral discourse in every effective legal system.1 The proportionality principle as classically formulated in bothjus ad bellum and jus in bello proceeds from the normative baseline that its value as a methodological tool is grounded on the cornerstone of a ‘proper purpose’.2 Combatants have affirmative rights under interconnected jus in bello principles, yet these rights carry correlative duties re- quiring that the loss of lives must be offset by equally serious matters if the conduct of war is to be justified. Military commanders see jus in bello proportionality as an essential element of professional ethos, providing the necessary latitude to accomplish their strategic and tac- tical mandates. As a necessary legal predicate, the overarching objective driven by the jus ad bellum analysis provides the evaluative template for assessing the legality of the strategic, operational, and tactical decisions necessarily undertaken during the armed conflict. Lawyers, philosophers, and just war scholars have long debated the proper relationship between jus ad bellum principles warranting the resort to force and the jus in bello utility of the proportionality principle. Nevertheless, the lex lata remains firm for the moment that each legal context functions as a distinct and independent body of law.3 Proportionality simultaneously empowers war- fighters and imposes concrete restraints over the conduct of armed conflicts when properly applied. The demonstrable gap between internationally accepted articulations of proportionality and its perceived application is not inevitable. However, the mere invocation of proportionality cannot become an effective extension of asymmetric combat power by artificially crippling combatant capabilities. The purpose of this chapter is to describe the subtle but undeniable role of jus post bellum considerations in linking otherwise disparate invocations of the proportionality principle. * Professor of the Practice of Law at the Vanderbilt Law School. 1 Aharon Barak, Proportionality: Constitutional Rights and Their Limitations (translated from Hebrew by Doron Kalir, Cambridge University Press 2012) 131. 2 Ibid. 3 Serena K. Sharma, ‘Reconsidering the Jus ad Bellum/Jus in Bello Distinction’, in Carsten Stahn and Jan Kleffner (eds), Jus Post Bellum: Towards a Law of Transition From Conflict to Peace (TMC Asser 2008) 9–31. Michael A. Newton, Jus Post Bellum and Proportionality In: Just Peace After Conflict. Edited by: Carsten Stahn and Jens Iverson, Oxford University Press (2020). © The several contributors. DOI: 10.1093/oso/9780198823285.003.0005 80 Michael A. Newton Concepts of proportionality are amongst the most controversial imperatives in waging modern conflicts from the legal, moral, and political perspectives. Their very termino- logical familiarity may result in overly formulaic applications in practice. Jus post bellum provides useful analytical continuity that can become a load- bearing pillar for affirmative articulations of the proportionality principle in a variety of usages. The difficulty in practice is that its parameters remain bounded by contextual challenges in every instance. Aharon Barak, of the Israeli Supreme Court, summarized this aspect of proportionality and its interrelationship with appropriate oversight as follows: The court will ask itself only if a reasonable military commander could have made the decision which was made. If the answer is yes, the court will not exchange the military commander’s security discretion with the security discretion of the court. Judicial re- view regarding military means to be taken is within the regular review of reasonable- ness . [T]he question is not what I would decide in a given circumstance, but rather whether the decision that the military commander made is a decision that a reasonable military commander was permitted to make. In that subject, special weight is to be granted to the military opinion of the officials who bear responsibility for security . Who decides about proportionality? Is it a military decision to be left to the reasonable application of the military, or a legal decision within the discretion of the judges? Our answer is that the pro- portionality of military means used in the fight against terror is a legal question left to the judges . Proportionality is not a standard of precision; at times there are a number of ways to fulfill its conditions . a zone of proportionality is created; it is the borders of that zone that the court guards.4 As noted above, jus post bellum considerations provide an important connecting premise. The precise parameters of this zone of proportionality remain very much in dispute amidst the complexity of modern armed conflicts and the rise of a globalized media. An adversary’s ability to broadcast (or fabricate) allegations of inappropriate conduct also adds an unprece- dented level of difficulty to modern proportionality determinations. Proportionality serves as one of the tendons linking otherwise distinct bodies of law into an interdependent whole. This intertwined relationship between various invocations of proportionality preserves the utility of the principle while ensuring its appropriate role within larger debates over the role for military force and the responsibilities of ethical war-fighters. This chapter addresses recurring confusions that cloud the application of proportion- ality. Section II addresses the oft- repeated misunderstanding of the relationship between the rule of law and the onset of armed conflict as a condition of human conduct. Because peace is the proper object of warfare, Section III describes commonalities of the propor- tionality principle as applied across varying fields of usage, while Section IV details the evo- lution of its modern normative content. Section V concludes by reviewing the role of jus post bellum as an embedded component connecting the invocation of proportionality as an aspect of military practices across domains and usages. 4 Aharon Barak, President (ret’d) Supreme Court of Isr., Address at the Jim Shasha Center of Strategic Studies of the Federmann School for Public Policy and Government of the Hebrew University of Jerusalem (18 Dec. 2007). Jus Post Bellum and Proportionality 81 II. ‘Correcting’ Cicero Embodying the classical conception of hostilities, Hugo Grotius quoted the Roman phil- osopher Cicero for the proposition that Inter bellum ac pacis nihil est medium (‘there is no medium between war and peace’).5 This archaic conception of conflict led to sharp intel- lectual cleavages drawn between the law of war and the law of peace.6 The conception of a legal firewall by which the prevailing body of law is automatically displaced by a wilder and impliedly non- legal set of norms is often said to originate some two thousand years ago from the mind of the famed orator and litigator Cicero. The philosophical and legal notion that antagonists may properly discount legal constraints when facing in extremis situations is captured in the oft-repeated sentiment from Cicero that ‘silent enim leges inter armes’. 7 The quote is often incorrectly attributed to saying that ‘in times of war, the law falls silent’.8 Cicero’s maxim has been invoked to argue that otherwise unlawful conduct may be per- missible in furtherance of a public good (presumably defined in utilitarian terms).9 Other advocates have invoked it to delineate peace (the courts are open and available for recourse) versus war (the courts are closed).10 Early British cases often quoted Cicero as embracing the idea that military matters fall outside the jurisdiction of common law courts.11 Courts in different jurisdictions repeatedly relied upon this same notion during the American Civil War and Reconstruction era cases, most famously in the Union arguments supportive of the suspension of the right to habeas corpus in Ex parte Milligan. In modern times, the phrase is more often used in discourse related to civil liberties during the investigation and prosecu- tion of terrorists. Heated debates over the rejection of civil liberties during recent armed conflicts rest on the fullest implications of the misquoted phrase. Justice Scalia’s dissent in the US Supreme 5 Hugo Grotius, De Jure Belli Ac Pacis [The Law of War and Peace] (first published 1625, trans. Francis W. Kelsey, Oxford Clarendon Press 1925) 832. Modern translation available online at <http:// oll.libertyfund.org/ titles/ grotius- the- rights- of- war- and- peace- 2005- ed- vol- 3- book- iii>; [<https:// perma.cc/ ZK8X- EGU8>] 6 The very title of Hugo Grotius’ classic work framed the issue in precisely this manner because that was the in- tellectual and philosophical fissure that he sought to explicate. 7 Cicero, Pro Milone, IV, xi. See Cicero, Marcus Tullius. M. Tulli Ciceronis pro T. Annio Milone ad iudices oratio (Clarendon Press, 1895). Text available online at <http:// www.thelatinlibrary.com/ cicero/ milo.shtml> ac- cessed 15 December 2019. 8 See e.g. William H. Rehnquist, ‘Dwight D. Opperman Lecture: Remarks of the Chief Justice of the United States’ (1999) 47 Drake Law Review 201, 205– 8 (‘Here we have an illustration of an old maxim of Roman law— Inter Arma Silent Leges—which loosely translated means that in time of war the laws are silent . The courts, for their part, have largely reserved the decisions favoring civil liberties in wartime to be handed down after the war was over. Again, we see the truth in the maxim Inter Arma Silent Leges—in time of war the laws are silent . per- haps we can accept the proposition that though the laws are not silent in wartime, they speak with a muted voice’).