It has become legal for the US president to assassinate US citizens, as long as they are Muslim

" The CIA sequence for a Predator strike ends with a missile but begins with a memo. Usually no more than two or three pages long, it bears the name of a suspected terrorist, the latest intelligence on his activities, and a case for why he should be added to a list of people the agency is trying to kill. The list typically contains about two dozen names, a number that expands each time a new memo is signed by CIA executives on the seventh floor at agency headquarters, and contracts as targets thousands of miles away, in places including Pakistan and Yemen, seem to spontaneously explode. No U.S. citizen has ever been on the CIA's target list, which mainly names Al Qaeda leaders, including Osama bin Laden, according to current and former U.S. officials. But that is expected to change as CIA analysts compile a case against a Muslim cleric who was born in New Mexico but now resides in Yemen. Anwar al Awlaki poses a dilemma for U.S. counter-terrorism officials. He is a U.S. citizen and until recently was mainly known as a preacher espousing radical Islamic views. But Awlaki's ties to November's shootings at Ft. Hood and the failed Christmas Day airline plot have helped convince CIA analysts that his role has changed." (thanks Dina)