Maybe if they keep trying, they’ll find a country that will prosecute him:

The Paris prosecutors’ office has dismissed a suit against Donald Rumsfeld accusing the former U.S. defense secretary of torture, human rights groups who brought the case said on Friday.
The plaintiffs, who included the French-based International Federation of Human Rights Leagues (FIDH) and the U.S. Center for Constitutional Rights (CCR), said Rumsfeld had authorized interrogation techniques that led to rights abuses.

(via)