Obama's Order to Kill

As one who was thrilled with Obama's election, it pains me to say this: but if he has ordered the killing/murder of an American citizen then he has violated the law and should be impeached. It does not matter that we MAY be at war (I do not think we are); if we are at war, then we shall always be - which means no end to limits on power. Further, if the President - any President - can order someone killed, then we have no law, no Constitutional limitations on our executive. The law would be what the President says it is, a Nixonian idea.