Future Tense

The Paradox of Nonlethal Weapons

Under international law, killing an enemy is more permissible than blinding him.

Oakland police officers fire tear gas to control a group of Occupy Wall Street protesters.

CS gas—a type of tear gas—is approved for use by police but not for the military.


Also in Slate: Brad Allenby and Carolyn Mattick explain why new military technologies require that we rewrite the “rules of war.”

Not all weapons are designed to kill; some are just meant to cause injury. Yet under the rules of war—a somewhat haphazard collection of ethical and legal directives—we are sometimes allowed to use lethal weapons even when certain nonlethal weapons are disallowed. In short, the lethal weapons are more permissible on the battlefield. As Donald Rumsfeld once complained “in many instances, our forces are allowed to shoot somebody and kill them, but they’re not allowed to use a nonlethal riot-control agent.” This is the paradox of nonlethal weapons, and it has been around for some time. Yet as military technology becomes increasingly capable of halting an enemy without killing him, it is a situation that international law must reconsider. Isn’t less deadly better?

Restrictions on weapons come from a range of sources. The most basic, though, stems from Additional Protocol I to the Geneva Conventions (§35), which holds, “Parties to a conflict and members of their armed forces do not have an unlimited choice of methods and means of warfare.” There are two general reasons for this, each of which tracks a different school of moral thought.

The first is that we must avoid, in the words of the International Committee of the Red Cross, “means and methods of warfare which … cause superfluous injury or unnecessary suffering” (Rule 70). The thinking here is largely consequentialist: Superfluous injury and unnecessary suffering are inherently wasteful. The stock examples are things like serrated bayonets or exploding bullets. Conventional bayonets and bullets are enough to remove opponents from the battlefield. Their more destructive complements cause substantial internal damage, leading to complicated surgeries, higher mortality, and so on. Since they arguably serve no legitimate military objective, they are prohibited.

Second, we must avoid weapons that are inhumane. Ever since Immanuel Kant, philosophers have wrestled with the notion of inhumanity, which critics allege is poorly explicated. The basic idea, though, is that some weapons evince overt cruelty or a lack of compassion and, therefore, should be proscribed. A principal example here is blinding lasers, which are decried by the ICRC (Rule 86) and Protocol IV to the Convention on Certain Conventional Weapons. Loss of vision is taken to be so merciless that blinding weapons fall beyond the pale and cannot be used among just combatants. Why death should be preferable to blindness is the obvious lacuna, but international humanitarian law is unequivocal.

Other international treaties, such as the Biological Weapons Convention (1972) and the Chemical Weapons Convention (1973), further limit what can be used on the battlefield. Much of the thinking behind these conventions segues with the above considerations, whether superfluous injury and unnecessary suffering—perhaps particularly as applied to collateral damage on noncombatants—or inhumanity. An interesting wrinkle, though, is that the Chemical Weapons Convention restricts the usage of various chemical weapons in armed conflict but not in law enforcement. For example, CS (2-chlorobenzalmalononitrile) and CN (2-chloroacetophenone) cause coughing, choking, headaches, nausea, vomiting, and pain. Law enforcement can use them, but military combatants cannot. It’s the same situation with calmatives like fentanyl.

When it comes to nonlethal weapons, these questions become more complicated. First, consider the notion of “superfluous injury and unnecessary suffering.” What is the benchmark against which these are meant to be measured? Certainly it is not plainly articulated, but the associated discussions usually pertain to removing an enemy from the battlefield. The thinking there—as mentioned above—is that, so long as the combatant can be rendered nonthreatening, any added injury or suffering does not accomplish anything.

However, there are broader considerations worth exploring. Those engaged in war want to limit the length of the conflict, the number of casualties, the expense, and so on. And it is possible that causing “superfluous injury and unnecessary suffering” to individual combatants could, in the long run, serve these goals—for example, by undermining the morale of the enemy and hastening the end of conflict. This need not escalate all the way to the controversial terror bombings of Germany during WWII, but, conceptually, a focus on individual combatants is too myopic. To be sure, combatants matter; they’re just not all that matters.

 Second, considerations of inhumanity—another way in which law might try to limit the use of certain nonlethal weapons—often rest upon the highly dubious assumption that injury is worse than death. The aforementioned blinding-weapons ban is a perfect example: We may be justified in annihilating an enemy force, but not in blinding it. But the scientific literature establishes that the ill effects of blindness on happiness are mostly ephemeral. Some period after blinding, subjects report that their happiness essentially returns to pre-injury levels. Given these sorts of results, it is curious that the ICRC sanctions killing ahead of blinding.

Third, why have different rules for law enforcement and for the military? Why do we let the military shoot but not incapacitate, especially since we let law enforcement incapacitate? If the issue were one of inhumanity—and such an argument has to be dubious—then incapacitation should be disallowed by both. The more obvious resolution, though, is to allow incapacitation by both, rather than disallow by both or allow by only one.

As military technologies develop, nonlethal weapons offer much promise. Riot control and other dispersing technologies—such as the Active Denial System, which is a millimeter-wave transmitter used for crowd control—can de-escalate conflict and, with it, limit human costs. Nevertheless, the ICRC and international humanitarian law take a dim view of at least some nonlethal weapons, despite allowing lethal counterparts. In doing so, though, these bodies owe an answer to a quite basic question: How can lethal weapons be preferable to nonlethal weapons? Of course it would be better if we didn’t have to use either. But until conflict can be eradicated like smallpox, we need to disarm the paradox.

This article was inspired by the 2012 Chautauqua Council on Emerging Technologies and 21st Century Conflict, sponsored by Arizona State University’s Consortium for Emerging Technologies, Military Operations, and National Security and Lincoln Center for Applied Ethics and held at the Chautauqua Institution in New York. Future Tense is a partnership of Arizona State, the New America Foundation, and Slate magazine.