Following a compliance review or investigation under Sec. 36.502, or at any other time in his or her discretion, the Attorney General may commence a civil action in any appropriate United States district court if the Attorney General has reasonable cause to believe that--
(a) Any person or group of persons is engaged in a pattern or practice of discrimination in violation of the Act or this part; or
(b) Any person or group of persons has been discriminated against in violation of the Act or this part and the discrimination raises an issue of general public importance.