The DOD airstrike that may have killed Taliban leader Mullah Mansour is interesting, from a legal perspective, at many levels. From an international law perspective, as Marty Lederman explains here, it looks to be another example of action under color of the much-discussed unwilling/unable principle (unless of course there was consent from Pakistan and the denials in the public record are mere theater for domestic consumption). As for U.S. domestic law: that seems to be an uninteresting question. As Marty notes in his post, the 2001 AUMF rather-obviously applies. But what if the AUMF did not apply, or had been repealed? It's an interesting thought experiment, useful for focusing attention on some key questions surrounding Article II authority.
It is not an entirely abstract question. The U.S. military (particularly SOF) is deployed to perform advise-and-assist mission in a wide variety of locations, many of which involve support to host governments facing insurgency or other forms of violence--and many of which thus involve a genuine risk of attack both on the military or security services we are there to support and on U.S. personnel themselves. Not all those circumstances relate to the 2001 AUMF. To what extent does Article II provide domestic law authority to use force in such cases?
Most would agree that U.S. personnnel are empowered to use force in immediate, personal self-defense in the event they actually are attacked, or when at attack on them is imminent in a strict, temporal sense. Change those assumptions, though, and things get tricky:
- Is the same true with respect to collective self-defense of the host-state personnel U.S. forces are there to advise-and-assist?
- Even if there is no Article II collective self-defense concept, does Article II at least permit self-defense force if one or more U.S. personnel choose to go into the field with a host-state unit (in an advisory capacity) and that unit then comes under attack?
- Is it necessary to show an actual or strictly-imminent attack, or is it enough to show there is a "continuing" threat of attack in the sense that we do not know the particulars of when the next attack will occur, but we do know/believe that the target has the intention and means to attack sooner or later?
I don't have anything to say right now about the collective self-defense questions above, other than that they are important and underexamined. Instead, I'll comment on the continuous-threat conception of self-defense.
I argued several years ago that the "continuous threat" concept of Article II self-defense has roots in U.S. legal thinking going back at least a few decades, up through and definitely including the Obama administration. This matters because there may be many instances of force conducted under color of the AUMF--such as the Mansour strike (which Secretary Kerry described as a "continuing imminent threat" scenario, and quite understandably so)--which in theory could have been conducted under Article II just as well (though obviously the politics and diplomacy of using force are better served by acting under an AUMF than under Article II standing alone).
That's something to bear in mind whenever there is talk about repeal of the AUMF. But of course the AUMF is still with us. So does this matter in the here-and-now? Yes, because AUMF-covered operations that take place outside areas of active hostilities are subject, for now, to contraints imposed by President Obama's Presidential Policy Guidance. The PPG among other things states that force should not be used absent a continuing, imminent threat to U.S. lives. The Mansour case can probably be viewed as an illustration of that test being applied--and satisfied--in a relatively-uncontroversial way.