In its new Law of War Manual, the Defense Department takes the position that harm to human shields, no matter how extensive, will be “understood not to prohibit attacks under the proportionality rule.” In my earlier post, I argue that this position is both legally and morally indefensible. In his response, Charlie Dunlap offers no legal defense of this position. Instead, he offers a broadly utilitarian argument that the proportionality rule should disregard harm to involuntary human shields, on the grounds that doing so will discourage their use. I will address this utilitarian argument below.

First, I wish to correct some misunderstandings. Dunlap claims that I “launch an ad hominem attack by denigrating the ‘morality’ of those who take a different view [from my own].” Nowhere in my post do I question the character of the manual’s authors. I am sure that they are fine people. Instead, I question the soundness of the manual’s position.

According to Dunlap, “Haque’s post suggests [that] the manual … exempt[s] the US military from the affirmative duty” to take feasible precautions to avoid harm to civilians. Nowhere in my post do I suggest any such thing. Dunlap later writes that “nowhere in his legal analysis does Haque even mention ‘feasible precautions’.” Arguably, this claim contradicts the previous claim. Finally, Dunlap asks “[i]sn’t that a pretty significant omission?” Since proportionality and precautions are distinct concepts, this is not a significant omission.

While precautions regulate how to carry out an attack, proportionality regulates whether to carry out an attack at all. Even if attacking forces take precautions to avoid harm to civilians, they may not attack if the harm to civilians that they cannot avoid outweighs the military advantage that they seek. Rather than inflict disproportionate harm on civilians, attacking forces must find another way to win. To see this, consider the following scenario:

Hospital: A fleeing combatant takes refuge in a hospital. The most discriminate weapons and tactics available to attackers will destroy half of the hospital, killing half of the patients.

Under international law, such an attack on the hospital would satisfy the precautions rule but violate the proportionality rule. In contrast, according to the manual, since the combatant is using the patients as passive, involuntary human shields, harm to the patients will not render an attack on the hospital disproportionate. This is the position that I reject. To clearly state and narrowly focus on a discrete legal issue is not, as Dunlap writes, “legally defective” but rather the starting point of all sound legal reasoning.

I would argue that the DOD’s position on feasible precautions is both legally and morally defective. Among other things, the manual declares that “if a commander determines that taking a precaution would result in operational risk (i.e., a risk of failing to accomplish the mission) or an increased risk of harm to their own forces, then the precaution would not be feasible and would not be required.” Apparently, the DOD thinks that “feasible” means “costless.” But let us leave that for another day.

Let us turn to Dunlap’s utilitarian argument that the proportionality rule should disregard harm to involuntary human shields in order to discourage their use. In my post, “I reject the view that IHL should strip individual civilians of legal protection in hopes of reducing aggregate harm.” On my view, IHL should offer each and every individual civilian general protection from intentional, unnecessary, and disproportionate harm. For example, on my view, IHL should not permit direct, terroristic attacks on civilians even when doing so would hasten the end of the war, thereby reducing aggregate harm to civilians. I trust that Dunlap will agree. Yet, according to Dunlap, IHL should disregard collateral harm to involuntary shields if doing so will discourage the future use of involuntary shields, thereby reducing aggregate harm to civilians. I find it implausible that civilian immunity can be disaggregated in this way.

In any event, Dunlap’s utilitarian argument fails on its own terms. Dunlap argues that the costs of “acquiring, guarding, feeding, housing, and otherwise supporting hostages” often outweigh the political benefits of doing so, such that many combatants will take hostages only if doing so will render attacking them unlawful. This argument fails, for the obvious reason that most involuntary shields are not hostages. The combatant who takes refuge in a residential building, the group that establishes a command center in a hospital, and the unit that fires rockets from a schoolyard take no hostages yet clearly use civilians as involuntary shields. Since such prototypical uses of human shields carry negligible costs for those who use them, any expected benefit — however small or speculative — will render their use instrumentally rational. If unscrupulous combatants will be targeted whether or not they use human shields but believe — correctly or incorrectly — that the deaths of human shields will redound to their broader strategic advantage, then they will continue to use them. If we seek to discourage the use of human shields then we must impose additional costs on those who use them, for example through punishment for war crimes.

Finally, Dunlap writes that my post “seems oblivious to the obvious moral issue [my] position invites: Who is to be ‘morally’ accountable for the civilian deaths that will inevitably occur when an attack is unnecessarily forgone and the target lives on to orchestrate further mayhem against untold numbers of civilians? Indeed, how many people should we ‘morally’ allow to be killed while waiting for the human shields to be absent?”

Indeed, attackers must balance the harm they expect to inflict on civilians against the harm they expect to prevent their adversaries from inflicting on civilians as well as on fellow soldiers. When the latter outweighs the former, they may attack. When the former outweighs the latter, they may not. There is a name for such a principle. That name is “proportionality.”