Take a Rare Look at How Obama Decides to Send Drones to Kill Americans

Put simply, the government believes that a lethal drone attack against an American citizen is justified if the targets are a) "senior operational leaders" of al-Qaeda or b) "an associated force."
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But what does "an associated force" mean? It seems like the guy who sells the terrorists bomb supplies would probably qualify, but what about the unknowing neighbor or the hired hand? Can we just kill them too in good conscience? Quite unfortunately, the government isn't exactly sure. The memo suggests that anyone who "present[s] an 'imminent' threat of violent attack against the United States" qualifies for assassination "a lawful killing in self defense," but that "does not require the United States to have clear evidence that a specific attack on U.S. persons and interests will take place in the immediate future." In other words, an "informed, high-level" official can order the killing of any American citizen that was "recently" involved in threatening "activities." As Isikoff points out, the memo fails to define both of those terms.

"This is a chilling document," said Jameel Jaffer, deputy legal director of the American Civil Liberties Union. "Basically, it argues that the government has the right to carry out the extrajudicial killing of an American citizen. … It recognizes some limits on the authority it sets out, but the limits are elastic and vaguely defined, and it's easy to see how they could be manipulated."