saab-bob and conehammer bring up a legitimate concern.
"But our own law may not be the only law that determines what happens in this country. At the very moment when Americans were so preoccupied with debates about the meaning of perjury or the requirements for impeachment, a series of events around the world offered a foretaste of what may become the next subject of heated legal debate for the United States: the proper reach of international law.
In Britain, the House of Lords decided last December that Augusto Pinochet could be held for extradition to Spain, where a magistrate sought to try the former Chilean dictator for tortures and murders committed by the Chilean government during Pinochet's period as chief of state. Meanwhile, halfway around the world, the government of Australia struggled to defend itself before a UN authority, which condemned the Australian government for allowing a uranium mine to be developed in the vicinity of an Australian national park. And here in the United States, the U.S. Supreme Court, after repeated displays of its own impatience with judicial second-guessing of capital sentences, suddenly ordered a halt to an execution in Texas and agreed to hear an appeal claiming that capital punishment in this case would violate international standards." source:
http://findarticles.com/p/articles/m...5/ai_54336464/ (a very interesting and informative read in its entirity)
If you google something like "International Law vs. US laws" you can find all kinds of examples of how International Law is already being considered when our courts, including our Supreme Court, render decisions.