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Thoughts on Distinction and Proportionality in the December 2016 Revision to the Law of War Manual

The new revisions to the DoD Law of War Manual that the Department of Defense released last week are welcome in several respects.  Four improvements are especially noteworthy:

First, a greatly expanded Section 5.11—like General Counsel Jennifer O’Connor’s recent speech at NYU—offers a much richer discussion of the sorts of precautions that the law of war requires, and of further precautions that the U.S. military often implements, over and above what the law requires, in its efforts to minimize civilian casualties. This section is invaluable, primarily to shape the conduct of military commanders in the future, but also to give those of us outside the military a better sense of the significant efforts the armed forces regularly make to try to minimize harm to civilians.

Second, as Geoff Corn notes, the new revision includes, in Sections and, a substantial treatment of how proportionality assessments are allocated between the commander ordering an attack and the subordinates executing that order. In Geoff’s words, “this is quite beneficial, and reinforces the complexities of combat action, the justifiable presumptive legality of superior orders and accordant expectation that subordinates will normally decisively execute superior orders, and the reality that complex balancing of interests made at one level of command may often be beyond the situational competence of subordinate commands ordered to execute attacks. However, none of this is absolute, and as the Manual notes, there may be times when a subordinate must question, and perhaps even disobey an order to conduct an attack.” Geoff is right to caution, however, that the new text also includes a “dangerous” suggestion that the obligation to disobey unlawful orders “is somehow qualified by the complexity of the [proportionality] rule itself”—a notion that “might . . . create a risk of too much reliance on superior attack judgments.”

Third, Section 5.11.7 explains that “when attempting to achieve a particular military advantage through an attack,” if a commander “confront[s] a choice among several military objectives for achieving that advantage,” the commander must select the object “the attack on which may be expected to cause the least danger to civilian lives and to civilian objects,” “provided that all other factors are equal.”  Sean Watts is concerned that this is too restrictive.  I, however, think it is a welcome illustration of the restrictive effect of the principle of necessity, which traces at least all the way back to Article 14 of the Lieber Code: “Military necessity, as understood by modern civilized nations, consists in the necessity of those measures which are indispensable for securing the ends of the war, and which are lawful according to the modern law and usages of war.”  Of course, “all other factors” will often not be “equal,” in which case the principle of necessity may allow the choice of a targeting option that is expected to cause greater danger to civilian lives than the alternative.  Nevertheless, it is a valuable development for the Manual to remind military decision-makers that the law of war constrains the use of force when there is no military imperative for choosing options that result in greater harm to civilians.  Nor should such a notion be especially problematic:  Most if not all of the applicable Rules of Engagement implemented by the armed services presumably already insist upon minimizing civilian casualties when choosing from among options on how force should be employed.

Fourth, and perhaps most significantly, DoD has eliminated the passages in the previous versions of the Manual, which Oona and I sharply criticized, indicating that civilians in or proximate to military objectives need not be counted in a commander’s proportionality analysis.   Indeed, the Manual now states expressly that those determining whether a planned attack would cause excessive civilian casualties “must consider” such civilians.  Furthermore, it appears that between the time of O’Connor’s speech and last week, DoD eliminated any express suggestion that if and when civilians make a “choice to support military operations in or on a military objective”—such as, presumably, by working in a munitions factory, accompanying the enemy armed forces, or providing medical assistance to such forces—such civilian “choices” “may be weighed by commanders as a factor in the proportionality analysis.”  (Oona, Mike Schmitt and I criticized that idea here.)

For these and other amendments, once again great appreciation is due to Jennifer O’Connor, Principal Deputy GC Bob Taylor, Deputy GC Chuck Allen, and the others at DoD who have been so genuinely welcoming of outside suggestions, and who have been working so diligently to improve the Manual.  Their openness to criticism, and their determination to continue improving the Manual, is rare and laudable.  If only more government agencies did likewise!

Not surprisingly, however, there remains a lot of important work to be done.  In particular, as I’ll explain in the remainder of this post, several new additions in the greatly expanded version of Part 5 of the Manual unfortunately introduce, or inadequately address, several ideas about distinction and proportionality that are mistaken—or at least sharply contested—and potentially very consequential, and the Manual offers little or no support for the proposition that they are consistent with the customary law of war.  What’s more, a handful of new footnotes in the most recent version of the Manual exacerbate such problems–and illustrate why the Manual‘s substantive footnotes are, on the whole, much more problematic than they are helpful.

  1. Distinction

The revision makes several changes to Section 5.4, regarding the principle of distinction, but it fails to address the deeply troubling and inaccurate statement in Section, which we have previously flagged, that “[u]nder customary international law, no legal presumption of civilian status exists for persons or objects.”  Nor do the new revisions address the dubious propositions that customary law does not include the requirement in AP I Article 50(1) that “[i]n case of doubt whether a person is a civilian, that person shall be considered to be a civilian,” and the corresponding provision of Article 52(3), establishing a similar presumption in a case of doubt about whether or not an object is dedicated to civilian purposes.

DoD officials, speaking on background, said that possible changes to these statements in Section were not the subject of this particular update, and that they welcome further comments or analysis on this and any other issue for consideration.

DoD should reconsider those statements sooner, rather than later, not only because the propositions in do not reflect either customary law or DoD practices, but also because, if taken at face value by commanders, they could encourage much less discriminating decisions to use force against persons and objects whose military or civilian character is uncertain.  As Oona, Mike and I wrote shortly before the release of this latest revised text:

The Department should amend the Manual to more accurately reflect customary law concerning how to treat individuals in cases of doubt about their status.  To be sure, it might be difficult to articulate precisely how much doubt is too much doubt to permit the use of force; even so, the Manual should, at a minimum, acknowledge that there is a “legal presumption of civilian status” when the commanding officer has little or no reason to think that a person is part of enemy forces (or a civilian directly participating in hostilities), where the preponderance of evidence points to civilian status, or where the officer is not fairly confident that the person is a lawful target.  We are confident such an amendment would reflect, not contradict, longstanding DoD practices. The recent DoD report on the 2015 airstrike of the Médicins Sans Frontières (MSF) hospital in Kunduz, Afghanistan, for example, explained that until the MSF Trauma Center was confirmed as a lawful target “it should have been presumed to be a civilian compound.”

2.  Proportionality

Systemic errors

Before turning to the specific, problematic applications of the proportionality principle in the revised Manual, it is important to note two other, more systemic mistakes in the Manual that bear on those applications.

First, Section 5.10 of the Manual very oddly, and in my view unhelpfully, insists that two different fundamental law-of-war rules each fall within the broad umbrella of what the Manual calls “the proportionality principle”: (i) the rule that combatants must refrain from attacks in which the expected loss of civilian life, injury to civilians, and damage to civilian objects incidental to the attack would be excessive in relation to the concrete and direct military advantage expected to be gained, and (ii) the rule that combatants must take feasible precautions in planning and conducting attacks to reduce the risk of harm to civilians and other persons and objects protected from being made the object of attack.

The first of these rules—the prohibition on attacks that are expected to cause “excessive” harm relative to the expected direct and concrete military advantage—is, indeed, what all the world recognizes as the “proportionality principle” or “the rule of proportionality.”  The latter rule, however—the requirement to take feasible precautions before attack to minimize civilian casualties—is generally understood as a distinct rule, rather than a component of the proportionality principle.

To be sure, the amended Manual expressly acknowledges that not everyone agrees with its consolidation of the two rules under a single “proportionality” aegis.  The Manual is also correct to note that the two rules are related in some respects, and can be mutually reinforcing:  For instance, compliance with the precautionary principle can “help ensure” that the subsequent attack satisfies the proportionality requirement, by reducing the risk of harm to civilians and other protected parties.  Indeed, AP I Article 57(2) even provides that the decision to refrain from launching an attack in violation of the proportionality (“excessive in relation”) requirement is itself a required “precaution.”

Even so, the two are distinct and independent rules, as the Manual acknowledges (“However, feasible precautions must be taken even when the attack is not expected to cause excessive incidental harm, and, even when feasible precautions have been taken, an attack could still be prohibited as one expected to cause excessive incidental harm.”).  Therefore, in my humble opinion there is little to be gained by confusingly suggesting—especially absent any supporting authority—that the feasible precautions requirement is a variant or component of “the proportionality principle.”[1]

Second, the amended Manual retains the incorrect and misleading notions, in Section 5.2.1, that (i) “the party controlling civilians and civilian objects has the primary responsibility for the protection of civilians and civilian objects,” and (ii) that “[c]ivilians also may share in the responsibility to take precautions for their own protection.” To illustrate these purported “responsibilities,” the appended footnote cites 1991 U.S. comments to the ICRC stating that “[t]he force that has control over the civilians has an obligation to place them in a safe place”; and that “[c]ivilians must exercise reasonable precaution to remove themselves from the vicinity of military objectives or military operations.”

In fact, the laws of war impose no such broad obligations, or responsibilities, upon defenders and civilians. It is of course true that the “controlling” party has an obligation to take certain feasible precautions to protect the civilian population, individual civilians and civilian objects under its control. But does that mean, for example, that DoD itself has an obligation to remove civilians from within and around the Pentagon during an armed conflict?  Of course not. (Indeed, just a few pages later (in Section 5.14.1) the Manual states that “legitimate military reasons often require locating or billeting military forces in urban areas or other areas where civilians are present.  For example, forces may be housed in populated areas to take advantage of existing facilities, such as facilities for shelter, health and sanitation, communications, or power.”)  And do civilians living near the Pentagon have an obligation to move? Surely not.

More to the point, this notion that the defenders and civilians have the “primary” responsibility to eliminate the presence of civilians near military objectives—even in cases in which the defending army has not deliberately forced civilians to be present near such targets for the purpose of deterring enemy attacks, and has not done anything else impermissible—infects the Manual’s subsequent, questionable discussion (see below) of how the proportionality principle purportedly applies with weakened force to such civilians in the proximity of military targets. The Manual’s suggestions about “primary” responsibilities, and responsibilities of civilians themselves, are lisleading and ought to be excised.

Four potentially problematic applications

I’ll now turn to the way in which the Manual applies the principle of proportionality to four different groups of civilians or other protected persons who may not be the subjects of a direct attack.

  1. Protected military personnel, including medical & religious personnel, the sick and wounded, and prisoners

Section 5.10.1 of the amended Manual states categorically that “[t]he principle of proportionality in conducting attacks imposes duties that apply to the protection of persons and objects that may not be made the object of attack.”  This describes some individuals within the military, such as medical and religious personnel, and persons hors de combat, none of whom can be made the object of attack.  Unfortunately, however, the Manual then almost immediately undermines this basic principle by insisting, in Section, that the prohibition on attacks expected to cause excessive incidental harm—that is to say, what all the world knows as the proportionality principle—“generally does not require consideration of military personnel and objects, even if they may not be made the object of attack, such as military medical personnel, the military wounded and sick, and military medical facilities.” (The same idea is repeated, as to non-international armed conflicts, in Sections,, and, and is suggested as to sick, shipwrecked and wounded persons in Section 7.3.3.)

There is a current disagreement about whether this is a proper understanding of the customary international law rule of proportionality with respect to persons who are in the armed forces but who are not subject to attack.  The ICRC argues that it is not (see, e.g., paragraph 1355, respecting the sick and wounded). Others disagree. As I wrote earlier:

From what little I know about this particular topic, the customary law of proportionality (and AP I, too, for that matter) has rarely considered whether and how military personnel who are protected — in the sense that they may not be targeted — must be accounted for in any proportionality analysis. (This category includes not only military religious and medical personnel, but also, e.g., wounded and sick forces, and perhaps some parlementaires, too.) I suspect that custom and treaty have not confronted this question because it has not been much of a problem: the vast majority of commanders — all but the most callous — undoubtedly do, for example, take anticipated harms to medical military personnel and the wounded into account in making targeting decisions, whether or not customary law would require them to do so.

There is probably some support for the notion that a proportionality analysis must take into account expected harm to protected military personnel, including medical personnel. According to the ICRC survey, for example, the Manuals in Australia, Canada, and New Zealand, and France’s Code of Defence, all insist that (in the words of the Australian Manual) “[p]roportionality requires a commander to weigh the military value arising from the success of the operation against the possible harmful effects to protected persons and objects.” And, at a minimum, it certainly would not be a stretch to say that the “dictates of conscience” (cf. the Martens Clause) would prohibit any commander from being completely indifferent to such collateral harms.

Perhaps there is a case to be made for the Manual’s view that the proportionality principle does not protect military personnel who cannot be made the target of attack.  The Manual does not offer any such case, however; indeed, it does not cite any authorities at all.  It merely reasons that “treaty provisions articulating a prohibition on attacks expected to cause excessive incidental harm,” such as the one in API, “do not reflect protections for military personnel who are protected from being made the object of attack.”  That is true, but it does not resolve the customary law question.  (The Manual provisions asserting this proposition as to noninternational conflicts (Sections, and point to an additional functional reason, in passing—namely, that the exclusion of such persons from the proportionality analysis is “due to their deliberate proximity to military objectives.”  That fact, however, cannot be an adequate basis for not considering them, as I explained earlier.).

Moreover, immediately after excluding such persons from the proportionality assessment, Section 5.10.1 then proceeds to insist that the requirement of feasible precautions does apply to such military personnel.  The Manual offers no reason, however, why customary law is best read to draw such a distinction between the proportionality and precaution requirements—insisting upon one but not the other—when it comes to these categories of protected persons.  Geoff Corn writes that this “compromise approach is actually perfectly aligned with the instincts and practices of commanders and their subordinates”—and that may well be so.  The burden is on DoD, however, to demonstrate that this odd halfway measure reflects customary law; and it has not carried that burden.

In this respect, it is noteworthy that the Chairman of the Joint Chief’s “Joint Methodology for Collateral Damage Estimation,” issued in 2009 (see Enclosure D), provides that the law of war “stipulates that anticipated civilian or noncombatant injury or loss of life and damage to civilian or noncombatant property incidental to attacks must not be excessive in relation to the expected military advantage to be gained”—and it specifically defines “noncombatants” to include “[m]ilitary medical personnel, chaplains, and those out of combat, including prisoners of war and the wounded, sick, and shipwrecked.”  The Joint Methodology, then—in contrast to the Manual—explains that the proportionality requirement and the rule of precaution each apply to, and protect, military personnel who may not themselves be targeted.  It does not hint at any two-track differentiation between the two legal restrictions.

I’m not sure how much of practical significance turns on this particular dispute.  It is hard to imagine that U.S. commanders very often, if ever, order a strike in which the expected harm to protected military personnel, such as medical personnel, and the sick and wounded, would be excessive in relation to the expected direct and concrete military advantage—especially after they have implemented feasible precautions. Which is all the more reason for the Manual not to introduce the notion, which might engender confusion and invite unnecessary criticism, that the proportionality rule protects certain categories of protected persons and not others.  This is one case in which there is no apparent need to start carving out exceptions.

2. Civilian medical personnel

What about medical personnel who are in the vicinity of legitimate military targets but who are not themselves part of the armed forces? This was the central concern of Oona’s original post.  Fortunately, the revised Manual has eliminated the earlier, express statements that such persons are not protected by the rule of proportionality.

As Geoff Corn points out, however, the revised Manual unfortunately does not “include a clear reminder that civilian medical facilities and personnel are always protected not only against deliberate attack, but also by both the precautions and proportionality rules.”  Moreover, Section provides that “[t]he incidental killing or wounding of [medical and religious] personnel, due to their presence among or in proximity to combatant elements actually engaged by fire directed at the latter, gives no just cause for complaint,” and that “[m]edical and religious personnel are deemed to have accepted the risk of death or injury due to their proximity to military operations.”  Because Section 7.8.1 describes the “categories of persons who are entitled to respect and protection as medical and religious personnel during military operations” to include “authorized staff of voluntary aid societies”; “staff of a recognized aid society of a neutral country”; and “the religious, medical, and hospital personnel of hospital ships and their crews,” some readers might understand these statements in Section to refer to all “medical and religious personnel,” regardless of whether they are part of the armed forces.  (Likewise, Section states that hospital ships and coastal rescue craft “will act at their own risk”; that such a ship “operating in proximity to combat operations assumes a certain risk of damage as a result of lawful enemy operations, including misidentification by enemy or friendly forces”; and that “the presence of hospital ships or coastal rescue craft does not serve to exempt nearby military objectives from attack due to the risk that the hospital ships or coastal rescue craft would be incidentally damaged.”)

In a background briefing, DoD officials stated that these sections of the Manual ( and are intended to cover those persons who are protected by relevant, cited provisions of the First and Second Geneva Conventions–primarily individuals who are part of the military forces.  Those cited provisions of the Geneva Conventions encompass at least some civilian personnel in some circumstances, such as the authorized staff of voluntary aid societies (e.g., theAmerican National Red Cross) and the staff of a recognized aid society of a neutral country, when they are impressed into the service of the armed forces.  See Manual Sections 4.9, 4.11 (when States choose to “subject such staff to military laws and regulations,” then “such personnel are to be treated like military medical and religious personnel”).  It does appear clear, however, that the provisions in question ( and are not intended to apply to an independent medical organization such as Médecins Sans Frontières.

In its next round of edits, DoD should amend Sections and to clarify that they apply only to military personnel, to specify when, if at all, civilian medical personnel are to be treated the same as military personnel, and, ideally, to expressly state that civilian medical personnel are fully protected by the proportionality principle.  (Likewise, DoD should also delete the passage in footnote 239 implying that the rule of proportionality did not regulate the U.S.’s incidental destruction of the civilian Bach Mai Hospital, outside Hanoi, because it was within a few hundred yards of the enemy’s main command center for air defense.)

3.  Civilians working in or near military objectives

It is very important to stress that the revised Manual has omitted the most troubling passage from Section of the previous iteration:  The Manual no longer states that “[h]arm to certain persons who may be employed in or on military objectives”–including persons authorized to accompany the armed forces, parlementaires, and “civilian workers who place themselves in or on a military objective, knowing that it is susceptible to attack, such as workers in munitions factories”–“would be understood not to prohibit attacks under the proportionality rule.”  The excision of that statement is the most salutary amendment in the new edition of the Manual.

Revised Section 5.12.1, however, now states a more modest, but still mistaken, view of the law, namely, that the “responsibility of the defending force” for the presence of such civilian workers “is a factor that may be considered in determining whether . . . harm to such civilians is excessive.”  (Note that this statement is not even limited to impermissible actions of the defending force–it applies whenever the enemy is “responsible” for the presence of civilian workers.)  Similarly, although Section correctly, and helpfully, confirms that “those determining whether a planned attack would be excessive must consider such [civilian] workers,” a nearby footnote then cites Bothe, et al., for the proposition that “[it] is . . . doubtful that incidental injury to persons serving the armed forces within a military objective will weigh as heavily in the application of the rule of proportionality as that part of the civilian population which is not so closely linked to military operations”; and it then also cites a 1977 conference comment by Burrus Carnahan that “State practice . . . suggests the existence of at least one intermediate category: persons who, while not taking a direct part in hostilities, are so intimately connected with a military objective that they have forfeited the right to be free from risk of collateral damage.”  (To be sure, as I discuss below, the Manual‘s footnotes are not intended to be authoritative, or illustrative of the textual propositions; even so, they too often leave an unwarranted and unfortunate misimpression.  And in this case, the text of Section 5.12.1 itself is problematic.)

For the reasons that Mike, Oona and I have explained, the law of war does not permit or encourage this sort of “relative” weighing of civilian lives in the proportionality calculus, depending on “factor[s]” such as whether the enemy is in part responsible for their presence, or the degree of “connection” between non-DPH civilians and the military effort.  It is not clear why DoD retained the passage in 5.12.1, and the footnote citations in, even after making its most recent changes to the Manual.  The Department should amend or remove them.[2]

4.  “Human shields”

The revised sections and passages on “human shields” include some improvements, but they remain troubling and confusing in other respects.  (For more on this topic, see generally Adil’s post.)

Of greatest significance, Section correctly explains that “[i]f civilians are being used as human shields, provided they are not taking a direct part in hostilities, they must be considered as civilians in determining whether a planned attack would be excessive, and feasible precautions must be taken to reduce the risk of harm to them.”  That is a very welcome addition.

That same section then goes on to say, however, somewhat cryptically, that “the enemy[’s] use of voluntary human shields may be considered as a factor in assessing the legality of an attack”—presumably even in cases in which the shields are not directly participating in hostilities.  (Accord Section 5.16.4.)  Again, this suggestion of variable valuations of civilian harms is not something that the proportionality principle of customary law recognizes.  Moreover, as Janina Dill has explained, the very idea that an attacking force can clearly distinguish between “voluntary” and “involuntary” human “shields” is dubious at the outset—it is helpful as an academic exercise, perhaps, but it’s unrealistic to view it as the sort of determination a commander can confidently make on the battlefield in the overwhelming majority of cases.[3]

As for persons who the enemy is using as “involuntary” human shields (which is what a commander will ordinarily have to assume to be the case), the Manual contains several troubling or confusing statements.  Section, for example, asserts that “[w]hen the attacking force causes harms that are the responsibility of the defending force due to its use of voluntary human shields . . . the responsibility of the defending force is a factor that may be considered in determining whether such harm is excessive.”  A citation to the U.K. Manual in footnote 417 is to similar effect: “Even where human shields are being used, the proportionality rule must be considered.  However, if the defenders put civilians or civilian objects at risk by placing military objectives in their midst or by placing civilians in or near military objectives, this is a factor to be taken into account in favour of the attackers in considering the legality of attacks on those objectives.”[4]  Worse still is the citation to a Hays Parks article in footnote 85: “While an attacker facing a target shielded from attack by civilians is not relieved from his duty to exercise reasonable precautions to minimize the loss of civilian life, neither is he obligated to assume any additional responsibility as a result of the illegal acts of the defender.  Were an attacker to do so, his erroneous assumption of additional responsibility with regard to protecting the civilians shielding a lawful target would serve as an incentive for a defender to continue to violate the law of war by exposing other innocent civilians to similar risk.”).  Footnote 509 contains similar statements.  For example, it cites the following Q&A from a 1975 Army Document: “Question: Suppose we are receiving fire from the enemy, and they are using unarmed civilians as shields. May we fire back, knowing that we will be killing many of these unarmed civilians?  Answer:  Yes.  We may fire since we have the right to defend ourselves.  The responsibility for innocent casualties falls upon those who would violate the law of war by using innocents as shields.”

To the extent these statements are read to suggest that the enemy’s responsibility for the human shields lowers or eliminates the constraints of the rule of proportionality—which might not be the only reading of them, but is the likely way in which many readers will understand them—they would be incorrect.  As Adil Haque explained in his post last week, “[t]he responsibility of the defending force, as such, does not affect the permissibility of the attacking force’s decision to strike.”  And the Manual itself is very clear that both voluntary and involuntary human shields must be counted in the proportionality analysis, even if it also (incorrectly) states that the defender’s responsibility for the proximity of such civilians “is a factor to be taken into account in favour of the attackers.”  In order to eliminate further confusion, I recommend that DoD remove from the Manual the passages quoted above, especially those in the footnotes.

Three additional problems (mostly) in footnotes

For reasons that are not explained, the revised version of Part 5 of the Manual contains several new footnotes that raise concerns about the Manual’s explication of how military decision-makers should apply the proportionality rule.

— Section states, correctly, that there “might be variation in how reasonable persons would apply the principle of proportionality in a given circumstance.”  A new footnote appended to that statement, however, cites an observation from a study by Professor Dill that “Commanders suggest that, proportionality judgements, in reality, often boil down to asking ‘can the estimated collateral damage be further reduced, through timing, choice of weapons or angle of attack?’  If the answer is no, the principle is considered to be fulfilled.”  This is a very troubling addition.  In the cited study, Professor Dill was accurately reporting what some commanders had told her in interviews—in effect, that if a decision-maker seeks to achieve a valid military objective in the way that most minimizes civilian harm, the proportionality requirement is automatically satisfied.  But Professor Dill was not endorsing that view, or suggesting that it is a correct view of customary law—to the contrary, as she has explained:

A . . . surprising narrative [among the commanders she interviewed] centered on the denial that the [proportionality] rule even required balancing military gain and loss of civilian life.  Instead, some commanders argued that proportionality demanded that the attacker made sure they had chosen a truly valuable target and did everything possible to minimize expected incidental harm.  Adequacy (that the attack will likely produce a military advantage) and necessity (that it is the mildest means to achieve this particular advantage) are indeed conditions of an attack’s legality.  Of course, they are not sufficient to make an attack proportionate under international humanitarian law.

(See also this post, in which Professor Dill explains that “[t]he collateral damage expected to be caused by an attack on a military objective even if that damage cannot be avoided—hence when the expected civilian harm is necessary for the achievement of the anticipated military advantage—may still be disproportionate.”)

— To similar effect, Section has been amended to more fully expand on the (somewhat misleading) idea that “[t]he principle of proportionality has been viewed as a legal restatement of the military concept of economy of force.”  Most troublingly, it adds a new footnote stating that “economy of force means that no more—or less—effort should be devoted to a task than is necessary to achieve the objective.”  Like the Dill footnote, this suggests that if a use of force is necessary to achieve a valid objective, it necessarily satisfies proportionality.  To be sure, if the “economy of force” principle is violated, there may well be a proportionality violation, too.  The Manual should not suggest, however—as this does—that proportionality is satisfied as long as no more force is devoted to the task “than is necessary to achieve the objective.”

— Section states, correctly, that a “commander’s decisions on proportionality must be reasonable” and that “for example, the commander must be able to explain the expected military importance of the target and why the anticipated civilian collateral injury or damage is not expected to be excessive.”  That is fine as far as it goes; but the corresponding footnote cites an Air Force Manual to the effect that “if the commander can clearly articulate in a reasonable manner what the military importance of the target is and why the anticipated civilian collateral injury or damage is outweighed by the military advantage to be gained, this will generally satisfy a ‘reasonable military commander’ standard.”  This is misleading:  A reasonable articulation of why the commander acted as he did does not mean that the balance he struck was itself reasonable, which is what the proportionality rule requires.

— Finally, the text of accurately makes the common observation that the proportionality calculus can involve a difficult weighing of seemingly incommensurable factors–a classic apples and oranges problem.  The attached footnote, however, quotes an excerpt from a 2006 DOJ appellate brief suggesting that courts and others can’t second-guess such assessments:  “The plaintiffs argue that the U.S. military’s use of herbicides was unlawful because the harm to persons and property caused by herbicide use was disproportionate to the anticipated military advantage. … In order to adjudicate the plaintiffs’ claims, a court would be required to balance the U.S. military’s interests in protecting our forces from ambush or other attack, and in weakening enemy forces, with the anticipated harms that might be caused by exposure to herbicides.  Even apart from the significant uncertainty about the effects of Agent Orange and other herbicides, this balancing would be inherently subjective since it would involve unlike quantities and values—e.g., the long-term health of civilians or enemy soldiers exposed to herbicides, with the death of U.S. forces and the accomplishment of military objectives.”

The 2006 DOJ brief, however, made this point simply in support of its argument that the proportionality principle “lack[s] the specificity and clear definition needed for an implied private [ATS] cause of action under Sosa”–not that such a calculation is altogether unreviewable.

* * * *

These examples are illustrative of a broader problem with the footnotes in the Manual.  Although section of the Manual states that “[c]itation to a particular source should not be interpreted to mean that the cited source represents an official DoD position, or to be an endorsement of the source in its entirety,” it also states that the footnote sources have been chosen because they “may contain a particularly helpful explanation or illustration,” or to “illustrate U.S. practice or legal interpretation.  Section 1.2.2 further explains that the Manual “cites sources in the footnotes to support or elaborate upon propositions in the main text.”  Far too often, I think, the Manual‘s footnotes at least appear to cite isolated historical actions of the U.S. government, or statements of U.S. officials, in order to suggest that because the U.S. has done or blessed something in the past, ergo it must not be a violation of the law of war.

Notwithstanding all of that, Department of Defense officials explained in a background briefing that readers should not assume the Department approves of, or agrees with, propositions of law contained in the footnotes, including in the new footnotes that raise troubling questions.  They also stressed that, as stated in Section, the footnotes cite particular sources “for a variety of reasons,” including “to help practitioners research particular topics discussed in the main text,” and that “[r]eviewing the cited sources in their entirety may provide additional contextual information, especially where sources are only partially quoted in the footnotes.”

I think it’s important to take these officials at their word concerning the limited authority of the Manual‘s footnotes.  One may hope, therefore, that military officers will not pay much heed to the footnotes–at least not for purposes of explicating the laws of war–but will instead concentrate on the text of the Manual.

In order to make sure there is no misunderstanding in the operational context, however, it would be far preferable for DoD simply to eliminate many of the “substantive” citations and quotations in the footnotes, especially where they merely represent an idiosyncratic or once-stated view of U.S. officials, and do not accurately demonstrate the accuracy of the text’s representation of what the laws of war provide.  Too often, the footnotes merely engender confusion and uncertainty, without offering any corresponding illumination of the law that might be useful for decision-makers in the field.  DoD therefore should seriously consider pruning them back considerably.

* * * *

I hope that DoD will, going forward, consider these new and remaining concerns about the Manual’s treatment of distinction and proportionality as carefully as it has responded to our previous suggestions, and those of many other observers.  Once again, I join the other participants in this Just Security “mini-forum” in extending my heartfelt thanks to the DoD officials who have worked so tirelessly to make the development of the Manual a truly “living” project, in which each iteration offers distinct and meaningful improvements on what has come before.

[1] From all that appears, the Manual engages in this unorthodox conflation of rules in order to support the later assertion that protected military personnel (e.g., religious and medical personnel) are protected by the “proportionality principle,” even though, as explained below, the Manual insists that commanders need not take account of the expected harm to such persons in the “excessiveness” calculus.

[2] The text of Section also includes these sentences: “The expected harm to civilian members of military aircrews on military aircraft or civilian technical advisers on warships does not render military aircraft or warships immune from attack. Similarly, munitions factories have not been deemed to be immune from attack just because of the presence of civilian workers inside the factory.” Because the simple presence of civilians never automatically makes any military target “immune from attack,” these sentences might well be read to suggest that the presence of such civilians cannot make the targets “immune” from attack by virtue of the proportionality rule. Therefore, they, too, should be removed or substantially rewritten.

Worst of all along these lines is footnote 240 of Part 5, which quotes Guenter Lewy’s study of Vietnam for the proposition that “once civilians act as support personnel they cease to be noncombatants and are subject to attack”—even when for example, when they act “under duress,” or when they act only as “porters”! Such a grossly overbroad notion of what we would today call the test for “direct participation in hostilities” is obviously a mischaracterization of the law, and should not appear in the Manual.

[3] Charlie Dunlap agrees about “the sheer impracticality if not literal impossibility of a battlespace determination” of whether and to what extent a “human shield” is acting voluntarily or involuntarily. From this he concludes, however (at least if I am reading him right), that all such “shields” should be deemed to be directly participating in hostilities, which would, if taken to its logical conclusion, not only eliminate the protections of precaution and proportionality, but make them legitimate targets of attack! (Charlie himself only expressly proposes that their lives be discounted in the proportionality analysis: “My suggested approach doesn’t require finding human shields as DPH.”) Needless to say, the Manual does not adopt any such indefensible view of humanitarian law. Nor does Charlie offer any evidence that this is, in fact, a proper understanding of customary law—his is, in effect, a plea for a development of the law in the direction of less protection for civilians in the proximity of lawful targets.

[4] As Adil notes, it is not clear that this statement in the UK Manual is designed as an instruction directed to the attackers themselves, and it is not, in any event “a strong foundation for the view that attackers may discount harm to human shields in determining the proportionality of an attack. Certainly, the UK Manual does not offer any legal reasoning to support such a view. Nor is such legal reasoning easy to find.”


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About the Author

is a professor at the Georgetown University Law Center.