This is the reason the US has refused to ratify the treaty governing War Crimes:

Former US Secretary of Defense Donald Rumsfeld got an unpleasant surprise during his visit to France today when human rights groups filed a complaint with the Paris Prosecutor before the “Court of First Instance” (Tribunal de Grande Instance) charging the chief architect of President George W. Bush's "war on terror" with ordering and authorizing torture.

International Federation for Human Rights (FIDH) along with the Center for Constitutional Rights (CCR), the European Center for Constitutional and Human Rights (ECCHR), and the French League for Human Rights (LDH) filed the complaint while Rumsfeld was in Paris for a talk sponsored by Foreign Policy magazine, and under French law, an investigation must be opened if an alleged torturer is inside France.

“France is under the obligation to investigate and prosecute Rumsfeld’s accountability for crimes of torture in Guantanamo and Iraq," said FIDH President Souhayr Belhassen. "France has no choice but to open an investigation if an alleged torturer is on its territory. I hope that the fight against impunity will not be sacrificed in the name of politics. We call on France to refuse to be a safe haven for criminals.”

“The filing of this French case against Rumsfeld demonstrates that we will not rest until those U.S. officials involved in the torture program are brought to justice," said CCR President Michael Ratner. "Rumsfeld must understand that he has no place to hide. A torturer is an enemy of all humankind.”