The U.S. Supreme Court has rejected an appeal by two U.S. citizens seeking to sue former Defense Secretary Donald Rumsfeld after they were allegedly tortured at a U.S. military prison in Iraq. Donald Vance and Nathan Ertel were detained in 2006 after collaborating with an FBI investigation into gunrunning by their employer, the Iraqi-owned firm Shield Group Security. They said they were subjected to extreme sleep deprivation, cold temperatures and prolonged interrogation before being released without ever being charged with a crime. Vance and Ertel said Rumsfeld was responsible for their mistreatment because he personally approved torture techniques used by U.S. forces in Iraq. But Monday’s decision maintains a lower court ruling that Rumsfeld is not liable.