The U.S. District Court for the District of Columbia issued the ruling. The state maps, passed by the Republican-dominated Texas legislature, redrew districts in a way that reduced the influence of minority voters, the court ruled.
November's election will likely use interim maps drawn by a federal court in San Antonio instead.
The Obama administration in 2011 blocked the maps, arguing they violated the 1965 Voting Rights Act, a law designed to protect the voting rights of minorities, primarily blacks in Southern states.
In rejecting the maps, the court could have stopped at ruling that they had a discriminatory effect, but it took the further step of ruling that the Texas legislature had a discriminatory intent in its drawing of the maps.
