Judge Andrew P. Napolitano: Obama's Secret Court for Killing

http://www.informationclearinghouse.info/article33940.htm

International law and the law of war, to both of which the U.S. is bound by treaty, as well as federal law and the Judeo-Christian values that underlie the Declaration of Independence (which guarantees the right to live) and the Constitution (which permits governmental interference with that right only after a congressional declaration of war or individual due process) all provide that the certainty of the identity of a human target, the sincerity of the wish for his death, the perception of his guilt and imminent danger are insufficient to justify the government's use of lethal force against him. The president may only lawfully kill after due process, in self-defense or under a declaration of war.

The reasons for the constitutional requirement of a congressional declaration of war are to provide a check on the president's lust for war by forcing him to obtain formal congressional approval, to isolate and identify the object of war so the president cannot kill whomever he pleases, to confine the warfare to the places where the object's military forces are located so the president cannot invade wherever he wishes, and to assure termination of the hostilities when the object of the war surrenders so the president cannot wage war without end.