Further Debate Over Whether There is a “Least Harmful Means” Rule in the Law of Armed Conflict

As readers of Opinio Juris know, Ryan Goodman argues in a forthcoming article in the European Journal of International Law  that:

“the modern law of armed conflict supports the following maxim: if enemy combatants can be put out of action by capturing them, they should not be injured; if they can be put out of action by injury, they should not be killed; and if they can be put out of action by light injury, grave injury should be avoided.”

Whether an obligation under the law of armed conflict (LOAC) to use the least harmful means possible against enemy belligerents exists has been the subject of much debate on this blog (1, 2, 3) and at Lawfare (see, for example, this)  and Jens Ohlin has also explored similar issues in his scholarship on the duty to capture.  I want to give readers a “heads-up” that Geoff Corn, Laurie Blank, Christopher Jenks, and Eric Talbot Jensen, who participated in the Lawfare discussion of Ryan’s piece (go to this link for a list that includes their posts, or go directly to their first post), have just posted to SSRN a full length article being published in the U.S. Naval War College’s International Law Studies on the question of whether a “least harmful means” rule exists. Their short answer is in the title: “Belligerent Targeting and the Invalidity of the Least Harmful Means Rule.” Here’s the abstract:

The law of armed conflict provides the authority to use lethal force as a first resort against identified enemy belligerent operatives. There is virtually no disagreement with the rule that once an enemy belligerent becomes hors de combat — what a soldier would recognizes as “combat ineffective” — this authority to employ deadly force terminates. Recently, however, some have forcefully asserted that the LOAC includes an obligation to capture in lieu of employing deadly force whenever doing so presents no meaningful risk to attacking forces, even when the enemy belligerent is neither physically disabled or manifesting surrender. Proponents of this obligation to capture rather than kill, or use the least harmful means to incapacitate enemy belligerents, do not contest the general authority to employ deadly force derived from belligerent status determinations. Instead, they insist that the conditions that rebut this presumptive attack authority are broader than the traditional understanding of the meaning of hors de combat embraced by military experts, and include any situation where an enemy belligerent who has yet to be rendered physically incapable of engaging in hostilities may be subdued without subjecting friendly forces to significant risk of harm.

This essay offers our collective and — we hope — comprehensive rebuttal of this least harmful means LOAC interpretation. First, Section I reviews the fundamental principles of the LOAC that permit status-based attacks against enemy belligerents with combat power highly likely to cause death unless and until the enemy is rendered physically incapable of participating in hostilities. Section II thoroughly analyzes the affirmative prohibitions on the use of force that the LOAC — and specifically Additional Protocol I — does require, and also highlights what Additional Protocol I does not require. In particular, the fact that Additional Protocol I — by any account the most humanitarian-oriented LOAC treaty ever developed — did not impose any affirmative least harmful means obligation vis à vis belligerents undermines any assertion that such an obligation may be derived from the positive LOAC. Finally, and perhaps most importantly, Section III emphasizes how this least harmful means concept, especially when derived from an expanded interpretation of the meaning of the concept of hors de combat, is fundamentally inconsistent with the tactical, operational, and strategic objectives that dictate employment of military power.

The LOAC must, as it has historically, remain rationally grounded in the realities of warfare. We are confident that anyone grappling with this issue understands that decisions related to the employment of combat power are not resolved in the quiet and safe confines of law libraries, academic conferences, or even courtrooms; they are resolved in the intensely demanding situations into which our nation thrusts our armed forces. The law must, as it always has, remain animated by the realities of warfare in the effort to strike a continuing credible balance between the authority to prevail on the battlefield and humanitarian objective of limiting unnecessary suffering. The clarity of the existing paradigm achieves that goal and does not include any legal obligation to use the least harmful means in targeting enemy belligerent personnel.