I recently authored an essay called The Duty to Capture, forthcoming in the Minnesota Law Review. A draft of the essay is available on ssrn and the final version will be published shortly. As Ken Anderson correctly notes at Lawfare, some readers might be misled by my title into thinking that I argued in favor of a broad reading of the duty to capture. Instead, I spend most of the essay expressing skepticism about various arguments that purport to find a duty to capture during many targeted killing or armed conflict operations. In that sense, the essay might be more appropriately titled "Is there a Duty to Capture?"
Of course, there is a duty to capture, and it applies during domestic law enforcement actions which are subject to the constitutional requirements of the Fourth and Fifth Amendments. There is also, arguably, a duty to attempt capture during situations governed by international human rights law. Consequently, I attempt to provide in the essay a complete understanding of this duty, when it arises, and what facts or legal requirements might displace or block it.
In particular, I spend much time analyzing attempts to "co-apply" international human rights law with the law of armed conflict. This "co-application" doctrine has gained increasing traction in recent years, with several scholars suggesting that both legal regimes can and should be applied at the same time. Consequently, rules from human rights law should be applied right along with the rules of armed conflict. The co-application view is especially prominent in cases of non-international armed conflict, which has relatively few codified rules; several scholars argue that the gaps should be filled by human rights law. This might be one way of finding a duty to capture during armed conflict situations.
In the "Duty to Capture," I express concern regarding these co-application doctrines. In particular, I argue that the concept of necessity in human rights law and the law of war mean completely different things. This is relavent because the duty to capture allegedly applies when killing an enemy combatant is no longer truly necessary. The question is what is meant by necessity in this context?
In human rights law, necessity often means "the least restrictive means." In other words, there is no other alternative, or at least not one with less infringement on the individual's liberties. So the action is necessary if no other action would achieve the desired results for the government actor in question.
In contrast, necessity in the law of war means something completely different. At least since the Lieber Code, necessity has been defined as "military necessity," which "admits of all direct destruction of life or limb of armed enemies," in the words of the Lieber Code. This definition is fundamentally incompatible with the least-restrictive means definition of necessity.
However, in a recent article, forthcoming in the European Journal of International Law, NYU Prof. Ryan Goodman argues that a least-restrictive means definition of necessity can be found in the laws of war, and he argues that support for this concept can be found in the travaux preparatoires for the Geneva Convention Additional Protocols. The practical consequence to this argument, if true, is that the law of war imposes a duty to attempt capture of enemy combatants where feasible.
I am very skeptical of this argument and am preparing a full response. Until then, various responses and replies by Prof. Goodman have been catalogued here (follow the links in the itemized list to read the full exchange).