Last week, Marty Lederman addressed the legality and wisdom of CIA engagement in targeted killings under domestic law. Applicable international law, however, suggests that CIA targeted killing, whether or not it’s legal, is surely unwise.

Marty does note that “the 2001 and 2002 AUMFs arguably provide authority for the President to employ both the CIA and DoD to use force against ISIL, in particular, in conformity with the laws of war” (emphasis added). One may quibble (and I do) with whether the 2001 AUMF, which concerns those who conducted the 9/11 attacks and those who harbor them, and the 2002 AUMF, which concerns the threat posed by Saddam Hussein’s alleged weapons of mass destruction, can possibly authorize hostilities against entities that didn’t even exist back then. But those are questions of domestic law and the separation of powers. International law, specifically the law of armed conflict, doesn’t care about whether Congress has authorized war or whether the executive has exceeded its constitutional powers in going to war. It cares about how hostilities in war are conducted, and about the protection of persons, like civilians and prisoners of war, not engaged in hostilities.

The principle of distinction is perhaps the single most significant aspect of the international law of armed conflict. While combatants (e.g., US armed forces) may be targeted, civilians (e.g., those working for the CIA) are immune from targeting, but lose their civilian protection while they directly participate in hostilities. Thus, it’s true that the international law of armed conflict does not categorically prohibit the CIA, despite its status as a civilian agency, from engaging in targeted killings, so the phrase “in conformity with the laws of war,” whether meant as a seal of approval or as a caveat, may be appropriate.

But it’s also worth noting that the US has been somewhat schizophrenic on the question of whether the law of armed conflict permits or prohibits civilian participation in hostilities. While it uses the CIA — and private contractors — to perform acts that may well amount to direct participation in hostilities, it has spent considerable energy trying to convince itself and the world that the law of armed conflict prohibits civilian participation in hostilities, even against what that body of law understands to be legitimate military objectives — namely, US soldiers. For example, in the ill-conceived Jawad and Khadr Guantánamo military commission cases, civilians were accused of murder “in violation of the laws of war” for engaging in hostilities against US forces.

The false notion that civilian participation in hostilities violates the laws of war is the natural consequence of the Bush administration’s decision to label detainees “unlawful enemy combatants” in order to deprive them of the rights of either combatants or civilians — the two categories recognized in the Geneva Conventions. While the Obama administration has put lipstick on that pig by changing the nomenclature to “unprivileged enemy belligerents,” the US military stubbornly persists in hewing to the false notion that “UEB” constitutes some kind of a third legal category that is neither combatant nor civilian.

So long as the US takes umbrage at civilians engaging in hostilities against US forces, it would be churlish, to say the least, for the US to authorize its civilians to engage in hostilities against its enemies in armed conflict. This kind of cherry-picking and cavalier treatment of international legal norms rightly causes other governments to plead “gimme a break” when the US lectures them about international law. More importantly, blurring the lines between combatant and civilian — as occurs when the CIA directly participates in hostilities — creates a precedent that undermines the principle of distinction, even if that participation is not unlawful. This puts civilians at risk in all armed conflicts, everywhere.  “Thank you,” says Saudi Arabia in Yemen, and Syria in Syria, and so on.

Not so long ago, then-Department of State Legal Adviser Harold Koh noted a category of official behaviors he termed “lawful but awful.” The CIA participating in targeted killings is an excellent candidate for that club.