The recent lawsuit filed by the estate of Al-Aulaqi against Panetta et al, over his targeted killing in Yemen, contains many different legal theories in an attempt to sustain at least one that would yield relief. (For recent commentary on the lawsuit, see here and here). But I find it particularly interesting that the lawsuit argues that "[a]t the time of the killing, the United States was not engaged in an armed conflict with or within Yemen." However, the lawsuit also goes on to assert that even assuming the existence of an armed conflict, the killing was illegal under international humanitarian law (IHL) because he was not directly participating in hostilities at the time he was killed.
What interests me most is the claim that the United States is not involved in an armed conflict in Yemen. Obviously, this is carefully worded. The lawsuit does not claim that there is no armed conflict in Yemen, because that stronger claim would offer little additional benefit to Aulaqi's legal claim. It is enough for the plaintiffs to assert that since the US was not party to the conflict, IHL did not govern the US killing of Aulaqi.
There are several different routes towards finding an armed conflict -- or several armed conflicts -- in Yemen. Presumably, plaintiffs will attempt to argue in this case that all of these routes are foreclosed. First, there is the obvious argument that the US is directly engaged in an armed conflict with al-Qaeda as a non-state actor, and that Aulaqi's killing took place as part of that armed conflict. The plaintiffs might assert that global al-Qaeda is too fractured to constitue a single non-state actor, or that Aulaqi was not a member of al-Qaeda "core" in Afghanistan and Pakistan when he was killed. But the U.S. government could always argue -- assuming the case is argued on merits rather than on procedural grounds -- that the U.S. government was engaged in an armed conflict with AQAP at the time of the killing, and it is unclear to me how the plaintiffs could block that argument from succeeding. At the very least, the government could argue that its drone strikes against AQAP in Yemen are part of that armed conflict. The only way of defeating that argument is for plaintiffs to argue that the AQAP is not sufficiently organized to constitute a party to an armed conflict, though that is a factual claim that might be difficult to sustain.
Of course, there is a completely different route to the same result. The US officials can also argue that there is a non-international armed conflict in Yemen between its government and insurgent forces; this claim seems difficult to deny. The drone strikes against Aulaqi and others could be pitched as an American intervention into that non-international armed conflict on the side of the Yemeni government, thus internationalizing the previously non-international armed conflict. Whether this then counts as a single armed conflict (Yemen and the US against the insurgents) or two parallel armed conflicts, would be immaterial. Either way, the US would be a party to an armed conflict and IHL would apply to the drone strikes.
As a final point, I was somewhat surprised that the complaint outlines completely different standards for the government's use of force under IHL and outside the context of armed conflict (i.e. peacetime). Although this is my view as well (separate standards apply whether IHL applies or not), there is a growing wave of legal thought in Europe that views IHL and human rights law as co-applicable in many situations like this. Although this co-application idea is well-regarded in many parts of the world it is much less accepted in the United States, so it is perhaps wise for the plaintiffs to have avoided it explicitly in the complaint. But it will be interesting to see if the co-application strategy nonetheless shows up in subsequent arguments in the case.