I am not a lawyer, but Glenn Greenwald is.
The U.S. really has bound itself to a treaty called the Convention Against Torture, signed by Ronald Reagan in 1988 and ratified by the U.S. Senate in 1994. When there are credible allegations that government officials have participated or been complicit in torture, that Convention really does compel all signatories -- in language as clear as can be devised -- to "submit the case to its competent authorities for the purpose of prosecution" (Art. 7(1)). And the treaty explicitly bars the standard excuses that America's political class is currently offering for refusing to investigate and prosecute: "No exceptional circumstances whatsoever, whether a state of war or a threat or war, internal political instability or any other public emergency, may be invoked as a justification of torture" and "an order from a superior officer or a public authority may not be invoked as a justification of torture" (Art. 2 (2-3)).
(crossposted from the Woodshed)