The Department of Justice sued to block Proposition 50, Californias newly approved congressional map, arguing that mapmaker Paul Mitchell and state leaders used race to create Latino-majority districts and asking a federal panel to bar the map before the candidate filing deadline later this month.Supporters including Gavin Newsom and spokesman Brandon Richards say voters adopted the plan to correct partisan gerrymanders and that the lawsuit is an effort by the California GOP to overturn voters will, while analysts such as Sean Trende and scholars including Richard L. Hasen warn that proving racial predominance over partisanship will be legally difficult.