— A judge on Friday narrowed the Metro transit system’s potential liability in a lawsuit brought by victims of the June 2009 crash that killed nine people, ruling that Metro can’t be faulted under federal law for using older rail cars. U.S. District Judge Reggie B. Walton said that because Metro is a quasi-government agency, it cannot be found liable for deciding to keep using the older rail cars that federal investigators found unsafe because they crumpled in crashes.