Well, I'm back from the American Library Association conference, to find that Dick Cheney is on the hot seat for creating an assassination team. This article by Jeremy Scahill shows that assassination has been a tool of Presidents, both Democrat and Republican, for decades, in spite of laws prohibiting it.
Is it ever justifiable? Even asking that question feels ethically uneasy. But if we know where a terrorist is, and that terrorist has killed in the past and is going to kill in the future, is it more moral than doing nothing and letting more die? On the other hand, assassination kills innocents as well as terrorists. This is one of those ethical questions that doesn't have a good choice. The West Wing dealt with the question in an interesting arc over months, in which President Bartlett, after agonizing over it, approved the assassination of a terrorist leader who was a member of a Middle Eastern, supposedly friendly, government. The secret came out after several months and the President's daughter was kidnapped in retaliation. Have I mentioned yet how much I like that show? ;-).