Guest Post: Henderson & Cavanagh on Self-Defense During Armed Conflict

Guest Post: Henderson & Cavanagh on Self-Defense During Armed Conflict

[Charles Kels is a major in the U.S. Air Force Reserve and an attorney for the Department of Homeland Security. He is writing in his personal capacity and his contribution is not meant to represent the views of the Department of Homeland Security, Air Force or Defense.]

Group Captain Henderson and Squadron Leader Cavanagh’s series of posts comparing and contrasting the Law of Armed Conflict (LOAC) and self-defense under criminal law (first, second, third, and fourth parts, along with the responses to posts one and four) provides an excellent analysis of how the legal basis for the application of force impacts the conditions upon its lawful use.

It is hard to argue with the central premise of the discussion: simply put, self-defense is not a part of LOAC. As the authors note, it is a term applicable to specific scenarios—namely, as a defense under criminal law and as a justification for the resort to force by states—and has different meanings depending upon the context in which it is invoked. This, by the way, is why I think the concept of “naked self-defense” as a standard for targeted killings is misplaced: it impermissibly (and I would argue counterproductively) conflates the jus ad bellum with the jus in bello.

The same can be said about the related issue of imminence. It has one meaning under a state’s right of self-defense, and another meaning under the law enforcement “force continuum,” but I’m unaware of any relevance to status-based targeting under LOAC. This is why some of the Obama administration’s pronouncements regarding imminent threats in the midst of what it deems an armed conflict have at times been so confusing.

The inapplicability of self-defense to LOAC is aptly encapsulated by Professor Ohlin vis-à-vis its interplay with the combatant’s privilege: the latter trumps the former, thereby rendering reliance upon it both unnecessary and self-defeating. Claiming self-defense in the face of criminal or disciplinary proceedings is essentially an excuse, but a privileged combatant who has exercised lethal force in compliance with LOAC has no need for vindication. In fact, he or she may be in line for a medal.

Yet, I am left wondering whether the discussion thus far elides a larger issue, rooted not in LOAC per se, but in the moral framework that undergirds it. That is, to what extent does the internal logic of LOAC as a coherent legal regime rest upon a generalized notion of individual self-defense? To the extent this insight has merit, I of course can’t take credit for it, although I have tried to flesh out its implications for remotely-waged warfare. It stems from Walzer’s famous formulation  (p. 34) of the “moral equality of soldiers,” and has found perhaps its most eloquent expression in the writing of legal philosopher Paul Kahn.

Essentially, Walzer’s notion is that “the capacity to injure” is what makes combatants legitimate targets in war. Kahn takes that argument to its logical conclusion, claiming that “the internal morality of warfare” is based upon the principle of “self-defense within conditions of reciprocal imposition of risk.” As such, what we lawyers call the combatant’s privilege is at heart “the soldier’s privilege of self-defense.”

Of course, given the irrelevance of imminence to LOAC, the risk posed by the identified enemy need not be immediate—hence another of Walzer’s well-known examples, the “naked soldier” (p. 138). Presumably, however, when that soldier gets dressed, he just may try and kill you (and may even be obligated to do so). This is what differentiates him from those who are hors de combat. So better to shoot him now, while you have the chance. What Michael Ignatieff calls the “tacit contract” of “kill or be killed” (p. 161) is still intact, even if attenuated.

One way to respond to Walzer, Kahn, and Ignatieff, et al. is simply to say that they’re wrong. Mutual risk has nothing to do with LOAC. To the extent that LOAC is concerned with promoting reciprocity, it’s a reciprocity of compliance, not physical peril. The jus in bello principle of proportionality, of course, imposes no requirement whatsoever with respect to parity in casualty rates among opposing forces.

Even so, it’s hard to deny that the reductive notion of combat as self-defense has intrinsic appeal, if nothing else than for providing a conceptually digestible précis of LOAC for those who actually have to implement its tenets in less than ideal circumstances. After all, the true value of LOAC is not just that it forbids some inhumane practices, but also that it legitimates certain acts of violence so that soldiers can do their jobs “without resorting to their own personal moral codes” or becoming paralyzed by principled indecision. This is especially so where, as in today’s conflicts, exhortations to abide by LOAC in order to incentivize compliance by the enemy are likely to fall on deaf ears (not to mention fail the straight-face test). At the end of the day, adhering to LOAC is about preserving our own humanity, not performing a risk-benefit analysis.

None of this detracts from the cogency of Henderson and Cavanagh’s observations, nor does it obviate the importance of avoiding confusion with respect to both the different contextual meanings of self-defense and their divergence from wartime targeting rules. However, I’m not sure that it’s possible to get away completely from accounting for permutations of self-defense when we talk about war-fighting. Otherwise, we risk being legally correct in the technical sense, while losing sight of the larger discussion over what it means to fight honorably.

Notify of

Moral arguments can be fun but even more confusing — and whose morality? a set of generally shared morality, logic unbound, nonsense posed as morality?
By the way, the phrase “imminent threat” logically and necessarily relates to something that is not even an actual threat at this time — no way in heck can such form a justification for use of force in self-defense under UN 51 or CIL.

Jens David Ohlin

This is an interesting post. Many of these issues are articulating in the writings of Jeff McMahan, as well as other philosophers writing in the revisionist Just War Tradition. The underlying impulse of this school of thought is that the morality of warfare depends on individual self-defense. The logical conclusion of JM’s view is that soldiers fighting on behalf of an unjust cause are not entitled to engage in combatancy because, as aggressors, they have no right of self-defense. I’m simplifying here, of course, but that’s the gist of the framework.


Jens: this is precisely the problem — logified personal preferences (or minority preferences) substitued for actual patterns of opinio juris about a specific matter. Check out Westlaw, secondary sources (law reviews) re: an “earthly morality” [which still would be reflecting of actual patterns of morality that are generally shared in the intenational community as opposed to actual patterns of opinio juris that are generally shared). Both sets of patterns are potentially dynamic (not “eternal”) and both may not be purely “logical.” The Realists in the 1920s and thereafter demonstrated by logic alone is unrealistic and can hide choice, preferences, and so forth.
Whose morality is an important issue, esp. when there may be a north/south divide or a westcentric set of moral preferences as opposed to others, and so forth.


instead of “by” I meant to type: why

Charles, thanks for the interesting post. I’m pleased that you appear to agree about the relevance of the law of self-defence during an armed conflict.

My concern about considering self-defence as a more abstract concept and tying that to fighting honourably is I would now be stepping away from the role of the legal advisor. I see my role as setting the legal left and right of arcs for the commander, and it is then for the commander to make decisions, including moral decisions, within that framework — although I know this view is not shared by all of my colleagues.

As this point goes to the role of the law and the role of the legal advisor, it is an extremely important debate and I am glad your post adds to the discussion.

[PS: As Bryan is enjoying leave on tropical island, the above are my views only]