TABLE OF CONTENTS I. INTRODUCTION 868 II. CORRECTING CICERO 869 III. COMMONALITIES AMONG DIFFERENT USES OF 873 PROPORTIONALITY A. The Pervasive Use of Negative Phraseology 873 B. Breadth of Permissible Discretion 875 IV. NORMATIVE CONTENT OF THE PROPORTIONALITY 878 PRINCIPLE A. Additional Protocol I Formulations 880 B. The ICC Crime of Disproportionate 882 Attacks V. CONCLUSION 885 I. INTRODUCTION
Ours is the "era of proportionality" in the sense that proportionality is an integral aspect of legal and moral discourse in every effective legal system. (2) Within the law of war, termed jus in hello, proportionality is centrally important to achieving military efficiency and moral fairness. Combatants have affirmative rights under interconnected jus in bello principles, yet these rights carry correlative duties requiring that the loss of lives must be offset by equally serious matters if the conduct of war is to be justified. Military commanders see proportionality as an essential element of professional ethos that provides the necessary latitude to accomplish their strategic and tactical mandates. Proportionality simultaneously imposes concrete restraints over the conduct of armed conflicts when properly applied.
Proportionality may well be the most controversial imperative in waging modern conflicts from the legal, moral, and political perspectives. This is particularly problematic for war-fighters given the emergence of a globalized system of international accountability. The adversary's ability to broadcast (or perhaps fabricate) allegations of inappropriate conduct worldwide adds an unprecedented level of difficulty to modern proportionality determinations. The demonstrable gap between internationally accepted articulations of proportionality and its perceived application is not inevitable. The mere invocation of proportionality cannot become an effective extension of asymmetric combat power by artificially crippling combatant capabilities.
Rather than serving as a necessary basis for a positive articulation of lawful force as an exception to the norm, jus in bello proportionality delineates the outer boundaries of the commander's appropriate discretion. 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 review regarding military means to be taken is within the regular review of reasonableness.... [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 proportionality 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. (3) The precise parameters of this zone of proportionality are very much in dispute amidst the complexity of modern armed conflicts and the rise of a globalized media. This short essay accordingly seeks to preserve the proportionality principle while ensuring its appropriate role within larger debates over the role for military force and the responsibilities of ethical war-fighters. It will, in seriatum, address confusions that cloud the application of proportionality, describe its commonalities as applied across varying fields of usage, and conclude by reviewing its normative content. The next Part addresses a recurring and oft-repeated misunderstanding of the relationship between the rule of law and the onset of armed conflict as a condition of human conduct. That understanding in turn necessitates consideration in Part III of the broader implications of the proportionality principle as it straddles diverse domains and usages. Part IV outlines the normative parameters that inform invocation of proportionality as an aspect of military practices.
Embodying the classical conception of hostilities, Hugo Grotius quoted the Roman philosopher Cicero for the proposition that Inter bellum ac pacis nihil est medium (e.g., "there is no medium between war and peace"). (4) This archaic conception of conflict led to sharp intellectual cleavages drawn between the Law of War and the Law of Peace. (5) The conception of a legal firewall by which the normally 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 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 "salus populwe supremus est lex (6)... silent enim leges inter armes." (7) The quote is often (incorrectly) attributed to say that "in times of war, the law falls silent." (8)
The phrase has been invoked to argue that conduct that would otherwise be unlawful may be permissible if it is in furtherance of a public good, (9) or in defining times of peace (the courts are open and available for recourse) versus war (the courts are closed). (10) Some early British cases quoted Cicero in embracing the idea that military matters fall outside the jurisdiction of common law courts. (11) Courts in different jurisdictions repeatedly relied upon this notion during the Civil War and Reconstruction era cases, most famously in the government's arguments in favor of suspending habeas corpus in Ex parte Milligan. In modern times, the phrase is more often used in discourse related to civil liberties during investigation and prosecution of terrorists.
Heated debates over rejection of civil liberties during recent armed conflicts rest on the fullest implications of the misquoted phrase. Justice Scalia's dissent in Hamdi v. Rumseld represents one of the more widely known recent incantations:
Many think it not only inevitable but entirely proper that liberty give way to security in times of national crisis--that, at the extremes of military exigency, inter arma silent leges. Whatever the general merits of the view that war silences law or modulates its voice, that view has no place in the interpretation and application of a Constitution designed precisely to confront war and, in a manner that accords with democratic principles, to accommodate it. Because the Court has proceeded to meet the current emergency in a manner the Constitution does not envision. I respectfully dissent. (12) When applied to the law of war domain, Clausewitz famously drew upon the mindset generally attributed to Cicero to postulate that:
war is an act of force, and there is no logical limit in the application of force... Attached to force are certain self-imposed, imperceptible limitations hardly worth mentioning, known as international law and custom, but they scarcely weaken it.... [In fact] kind-hearted people might... think that there was some ingenious way to disarm or defeat an enemy without bloodshed, and might imagine that this is the true goal of the art of war. Pleasant as it sounds, it is a fallacy that must be exposed; war is such a dangerous business that the mistakes which come from kindness are the very worst... (13) As recently as January 2018, a sitting judge on the Appeals Chamber of the International Criminal Court invoked this notion to infer in open court that the appeal of Jean Pierre Bemba from his conviction for war crimes might be unfounded. (14) However, despite its repeated incantations, the argument that Cicero advocated suspension of applicable law in times of warfare is unfounded.
Few lawyers have distinguished the popular mischaracterization from what Cicero actually said in its context. Cicero was arguing in defense of his close friend, Milo, who had been set upon by armed brigands under the leadership of a political foe while travelling. On trial for the killing of Clodius, Cicero argued (not unlike other defense attorneys through the centuries) that a limited right of self-defense displaces other norms that might otherwise prohibit killing. (15) Relying on this theory of self-defense under circumstances that rendered the killing understandable and perhaps even laudable, the relevant portion of Cicero's oration reads as follows:
There is then, judges, a law of this kind--not written, but inborn--which we have apprehended, drank in and extracted from nature herself; in conformity to which we have not been taught, but made; in which we have not been educated, but ingrained; and this law is, that if our life fall under peril from any ambush, violence, or weapon, whether of robbers or of personal enemies, recourse should be had to every honorable means to safety. For the laws are silent in the midst of arms. (16) With respect to jus in bello, the takeaway is plain. Of course the law applies, but it does so in modified form and with an entirely different set of normative benchmarks. Grotius implicitly recognized this truism in the Prolegomena to his classic work by noting that "[i]f laws are silent among arms,' this is true only of civil laws and of laws relating to the judiciary and the...