The Texas attorney general, Greg Abbott, who is representing the state, said he would appeal the decision. “Today’s decision extends the Voting Rights Act beyond the limits intended by Congress and beyond the boundaries imposed by the Constitution,” Mr. Abbott said in a statement.

Michael Li, an election law lawyer in Dallas who runs a Web site following the case, Txredistricting.org, said that because the Washington court had no power to fix the maps — only to decide whether to grant or deny preclearance — the case now moves back to Texas, where the federal judges in San Antonio will most likely fix the problems identified by the Washington court. They also may let the Legislature try to redraw the maps.

The judges in Washington found that one largely Hispanic Congressional district in South Texas that includes Corpus Christi had its minority voting strength diluted when it was redrawn to a majority-Anglo district. In the 23rd Congressional District in West Texas, the judges ruled that drawers “consciously replaced many of the district’s active Hispanic voters with low-turnout Hispanic voters in an effort to strengthen the voting power of C.D. 23’s Anglo citizens,” reducing Hispanic voting power “without making it look like anything in C.D. 23 had changed.”

The judges found that the Congressional map as a whole was enacted with a “discriminatory purpose,” and they cited the concerns of black and Hispanic members of Congress who testified that they were excluded from the process of drafting the maps. In addition, several minority Congress members had the economic generators of their districts and their own district offices removed in the maps, though, as the judges pointed out, “no such surgery was performed on the districts of Anglo incumbents.”

Lawyers for Mr. Abbott argued that the maps were drawn to help Republicans maintain power but not to discriminate, and that drawers did not know where district offices were located.