Not that anyone pays any attention to my opinion, but I think that the complaints about using drones for targeting killing are probably largely misplaced. Drones are bombs. Bombs are instruments of war. If one believes that we are at war with a stateless army, then killing members of that army with drones is preferable to the alternatives (e.g., cluster bombs, saturation bombing, and so on).
The real problem is that we have not really declared war. We have this strange Authorization of Military Force (see here for legal analysis), which probably applies to the Taliban in Pakistan and Afghanistan, and almost certainly does not apply to Al Qaida in the Arabian Peninsula and other groups that formed subsequent to 9/11. If the Executive wants to continue to use drone strikes–or make war by any means outside of the AfPak region– he should ask for an updated AUMF. This is not a nicety. It’s one major means by which we prevent presidents from becoming tyrants.
As for assassinating American citizens, or any non-combatant, military or not, that’s plainly illegal. The claim for killing Anwar al-Awlaki was that he was serving as a chaplain for AQAP. Would we accept the targeting of an American chaplain as a legitimate action by an enemy? On many levels [fn], this was a war crime. Add one more level of wrongness for the killing of his son. The fact that drones were used is irrelevant to the basic legal issues and when the left focuses on the technology, it undermines its arguments against targeted killing.
They do have a better case against Israeli action, since Operation Cast Lead and subsequent events made it abundantly evident that Israel is involved in collective punishment against an occupied nation, not warfare.
As I say, not that anyone will listen.
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fn. Lack of authorization for action against AQAP. lack of due process, since in principle al-Awlaki might have been a hostage rather than an active collaborator. Lack of evidence that he was an active combatant. For son, add targeting of a minor. More broadly, there’s the question of whether there’s even adequate oversight over who gets put on the kill list and whether there’s oversight over issues of “collateral damage,” i.e., dead innocent people.