The federal government can use deadly force during a riot under specific circumstances, as outlined by the Posse Comitatus Act and the Insurrection Act. The Posse Comitatus Act, passed in 1878, prohibits the use of military forces for law enforcement on U.S. soil unless expressly authorized by Congress. The Insurrection Act, invoked by the president, allows for the use of military forces to suppress insurrections, domestic violence, unlawful combinations, or conspiracies.