That is no small step for an American president. Yet there has been little discussion of assassination in Congress or in the media. There should be more. It is worth looking at the history of assassinations and asking whether the president and Congress really want the United States to support efforts to kill heads of state, even wicked ones such as Gaddafi. Aside from the moral questions, assassination invites instability and blowback…

As Ward Thomas, a professor at the College of the Holy Cross, writes in “The Ethics of Destruction,” the norm against assassination gradually loosened after World War II. It was recognized that heads of state could be terrorists and war criminals — if not human monsters. In 1986, after Gaddafi was held responsible for a terrorist attack that killed American servicemen in a nightclub in Berlin, the United States bombed Gaddafi’s tent in Libya, killing some of his relatives. In the opening blow of the 2003 Iraq war, American bombers attempted to kill Saddam Hussein, believing, thanks to faulty intelligence, that he was at a location outside Baghdad. The U.S. executive order banning assassinations, adopted after earlier CIA plots against Cuba’s Fidel Castro and others were exposed in 1975, does not apply in wartime. “The laws of war clearly permit states to use lethal force against the chain of command of military forces who are engaged in armed conflict,” says former CIA general counsel Jeffrey H. Smith. “But we need to be very careful how we use that force, to make sure we are not setting a dangerous precedent.”