Bring on the trials
Unless it wants to become an isolated international pariah with which no other nation will sign agreements of any kind, the United States had better collect its excrement into a single place and start prosecuting people for torture. It has a legal obligation under several international treaties to do so and unless it plans to repudiate its treaty obligations, and thus invalidate all international treaties it has signed, it must fulfil those obligations.
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)).