Richard Melson

August 2006

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Perspectives Paper No. 20, August 15, 2006

Proportionality in the Modern Law of War:
An Unenforceable Norm, or the Answer to our Dilemma?

Amichai Cohen

Executive Summary: "Proportionality" has become a common term, widely used by human rights organizations, politicians, soldiers and laypersons, but its precise legal meaning is little understood. The goal of this paper is to clarify the parameters of the use of the term and identify the problems confronting attempts to apply it. The final section of the paper mentions various solutions to these problems and alludes to the concept’s application in the context of the present war between Israel and the Hizballah.

I. Introduction: The Limits of our Discussion

"Proportionality" has become a common term, widely used by human rights organizations, politicians, soldiers and laypersons. But its precise legal meaning is little understood. NGOs allege that a certain attack was disproportionate because civilians were killed; military officers retort that the action was proportional because the enemy fired first. From a legal standpoint, both claims are inaccurate, and based on irrelevant conceptions of proportionality. The goal of this paper is not to justify or discredit the use of proportionality, but rather to clarify its parameters, and identify the problems confronting attempts to apply it.

It is important to stress at the outset that the body of international law known as "the law of war" uses the term proportionality in several contexts. This short review will not be able to cover all of them and will focus on the principle of proportionality within a war, and hence as part of what is known as the jus in bello (i.e. the ways in which force may legitimately be employed during the course of conflict). The uses of the term in the context of the jus ad bellum, which is concerned with the right to initiate uses of force in self-defense will not be dealt with here.

II. The History and Definition of the Principle of Proportionality

Although the term proportionality does not appear in any international legal text, convention or treaty, it boasts a long pedigree within the rules of war. Some scholars claim that the concept was already a part of the medieval laws of war, which posited that war could be deemed to be just, and hence legitimate, only if its gains exceeded the horrors that it wrought. Proportionality, in this reading, was implicit in the conception that war must be illegal if the ends cannot justify the means.

A more concrete use of the concept is evident in the 1907 Hague Regulations, which are considered customary international law. These adopted as a basic rule the principle of distinction, which outlawed direct attacks against non-military targets (Article 25). But this did not mean that all other attacks, for instance attacks against targets that were both civilian and military, could be undertaken without restraint. Article 23(e) prohibits employing "arms, projectiles, or material calculated to cause unnecessary suffering", while Article 27 directs the attacking army to spare, as far as possible, buildings which have religious or cultural importance.

General agreement about more precise aspects of proportionality was not attained until the Geneva Convention of 1977. The first additional protocol to the document then approved includes several specific clauses, which are considered to embody the concept. The clearest of these is Article 51(5), which states:

5. Among others, the following types of attacks are to be considered as indiscriminate [and therefore prohibited - AC]:
(a) An attack by bombardment by any methods or means which treats as a single military objective a number of clearly separated and distinct military objectives located in a city, town, village or other area containing a similar concentration of civilians or civilian objects; and
(b) An attack which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.

As can be seen, the principle of proportionality, as embodied in this and other similar articles in the first protocol, is based on two complementary ideas. The first is that measures have to be taken to limit the harm that efforts to attain military goals will cause to civilian populations. Geographically, the military target should be defined in the narrowest possible way. Similarly, the attacking power should consider whether there is a way to achieve the military objective with less or no damage to the civilian population. Thus employed, proportionality constitutes a logical extension of the principle of distinction: everything should be done to target only military objectives.

The second section of Article 51(5) is more innovative and embodies a further facet of proportionality. It orders the attacking power to make an audit of its proposed operation, comparing the foreseeable damage to the civilian population with the expected military advantage. This is not merely an extension of the principle of distinction. It requires the army to relinquish a military advantage if its attainment threatens to cause disproportionate harm to the civilian population. Damage to the civilian population becomes prohibited once it is seen to be excessive in relation to the military advantage. It is this last requirement that has generated most of the problems with the concept of proportionality.

III. Problems with the Concept of Proportionality, and some Preliminary Answers

This last section will outline difficulties in terms of implementation and application of the concept of proportionality, and - where relevant - mention some of the solutions that have been applied. Finally, the circumstances in which the concept should be applied in the context of the present war between Israel and the Hizballah will be briefly addressed.

A. The Future is Unclear

The most obvious difficulty generated by the concept of proportionality relates to the feasibility of rational choice in battlefield situations. In essence, the concept of proportionality assumes that the attacker has an option. It can either take action, bringing to bear its full military advantage, or it can relinquish a small part of its military advantage, in order to significantly limit the damage that it will cause to civilians. Confronted with that choice, proportionality requires the attacker to choose the latter course.

In reality, however, military operations very rarely offer such a clear-cut choice. In most cases, the dangers and potential of the battlefield are unknown. The commanding officer simply cannot make an informed assessment of the harm to the civilian population vis--vis the gains from a specific military attack. Hence, the first problem with proportionality is that it seems to place an unrealistic burden on the attacker – to make a cost-benefit analysis in the midst of a battle.

Closer analysis reveals that this criticism is less powerful than it initially appears, for even if armies cannot be expected to make precise assessments with respect to prospective military advantages and harm to civilians, they can be expected to think about civilian casualties and their limitation. In this sense, proportionality mandates an institutional search for creative solutions to the problem of collateral damage.

Studies of how armies actually behave shows that this requirement is sometimes met. Thus, NATO forces in the Kosovo campaign implemented a system of authorization, which, they claimed, reduced civilian casualties to a minimum. It has been reported that every IDF resort to targeted killing requires the authorization of, amongst others, the Judge Advocate General or a member of his staff.

B. What is to be considered a Legitimate Military Advantage?

A further issue relates to the correct application of the term "military advantage". This touches upon several general ramifications, including the entire subject of legitimate targets in war, which cannot be dealt with in the confines of the present paper. More specifically, however, it relates to the application of the concept of proportionality in such areas as the duty to defend one's own soldiers. Let us assume that a military commander knows that his proposed attack on a military objective will necessarily endanger civilian life. He can attack the target in a way that will reduce the harm caused to civilians, but knows that by doing so he will expose his own troops to greater dangers. Can he realistically be expected to risk some of his own soldiers, in order to save the lives of enemy civilians?

Similar questions arise with respect to targeted killings of terrorists. Clearly, commanders of such operations must take into account the likelihood that their implementation endangers anyone in the immediate vicinity of the terrorist who is targeted. However, they must also weigh the threat that the terrorist, unless killed, will inevitably pose to the intended victims of his planned suicide bombing. Is there a gauge for comparing the price to be paid by the two sides?

The answer, of course, is that there is not. The committee appointed by the prosecutor of the International Criminal Tribunal for Former Yugoslavia (ICTY) concluded that protecting one’s own soldiers by using an aerial campaign is allowed, even though it risks a greater number of civilian lives. This legal conclusion is far from being accepted by all international lawyers as a correct statement of international law. However, it signifies a trend towards a realization that international humanitarian law cannot detach itself from the interests of the army, and must acknowledge that if states and military commanders are to apply the rule of proportionality, realistic expectation should take into account their biases.

C. The Manipulation of the Concept of Proportionality

Especially in asymmetric conflicts, where one side is a state and the other a non-state combatant, the principle of proportionality is often manipulated. The non-state actor, sometimes a terrorist organization, sometimes a rebel force, uses civilian populations as a shield to protect its fighters. The latter intentionally take cover within areas of civilian residence in order to prevent the enemy from attacking. This method of war is of course a war crime, and one of the worst ones, at that. Indeed, in this situation the principle of proportionality seems to exercise an adverse effect on the lives of civilians. Precisely because of the norm of proportionality, non-state actors actually use civilians more in battle, instead of using them less.

Some commentators claim that situations such as this mandate fundamental revisions in the laws of war, with the principle of proportionality being thought especially ill-suited to the war on terror. Yet this rush to change the laws of war is a little too hasty. The laws of war, including the concept of proportionality, have shown an ability to adapt to the changing environment without the need to rewrite or discard them altogether. For example it is widely accepted that when terrorists use civilian populations as human shields, it is legal for the attacking party to cause more collateral damage. This must not be taken to imply that if one side in a conflict commits a war crime the other is at liberty to commit a war crime in retaliation. What it does mean is that the correct application of the concept of proportionality changes once terrorists attempt to use civilians as shields from an attack. In these situations the restraints on collateral damage are relaxed, but certainly not altogether abandoned.

D. The Cumulative Effect of Proportionality

A recent development in the issue of proportionality seems to be concerned with the cumulative effects of war. If, on the whole, the number of civilian casualties is larger than appears justified by the military goals of the operation, the operation itself becomes illegitimate.

This possibility was noted by the International Criminal Tribunal for Former Yugoslavia (ICTY), which explicitly stated:

"… in case of repeated attacks, all or most of them falling within the grey area between indisputable legality and unlawfulness, it might be warranted to conclude that the cumulative effect of such acts entails that they may not be in keeping with international law".

The ICTY seems to suggest that even if, individually, each specific action taken by a combatant can be considered arguably legitimate, in the sense that it meets the criteria of proportionality, the totality of civilian casualties caused by the overall campaign can be judged exaggerated. The charge that Israel’s response to Hizballah attacks in the present war in Lebanon has been disproportional seems to rest on similar grounds. The objection is not so much to the operations against Hizballah per se, but rather to the sum total of collateral damage that those operations have caused to Lebanese civilians.

This position is by no means universally accepted. Some claim that cumulative effects merely shift the burden of proof to the attacking party to show that its actions were legitimate. Others strongly reject this widening of the effects of proportionality as a subjective, even hypocritical way to judge the legitimacy of war. How can the importance of a military operation be objectively judged?

This criticism might be misdirected. Quite apart from legal niceties, prudence also suggests that the cumulative test be given due consideration. There is some importance in the fact that the world views a military operation as legitimate. After all, once a war is branded as illegitimate, the conduct of military operations themselves might become more difficult. Even if other countries do not intervene to stop the carnage, as they sometimes may, in a democracy, internal opposition will gather strength. Cumulative proportionality, then, acts as a clear boundary-marker, and in this sense at least, law and wisdom seem to converge.

Dr. Amichai Cohen, LL.M., J.S.D. Yale Law School, teaches international law at the Ono Academic College.

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Begin-Sadat (BESA) Center for Strategic Studies
Bar-Ilan University

Ramat Gan 52900

BESA Perspectives No. 20 Proportionality in the Modern Law of War

Amichai Cohen

Attachment: Perspectives20-AmichaiCohen-Proportionality.pdf (0.19 MB)

Tuesday, August 15, 2006