Hispanic and black voters in Texas were vindicated on Tuesday when a federal three-judge panel rejected the state’s new redistricting plans for Congressional and state legislative seats. A panel of the United States District Court in the District of Columbia properly found that the maps, based on the 2010 census, had a discriminatory purpose and effect in reducing the ability of minority voters to elect candidates they favor.

The evidence of the discrimination was stark. Almost 90 percent of the 4.3 million growth in the state’s population in the last decade came from minority residents. That growth qualified Texas for four additional Congressional seats, and it required the state to create new voting districts. Yet instead of adding districts in which minority voters could elect candidates of their choice, the Republican-controlled Legislature drew the districts in a way that reduced the number represented by members of minority groups. About some districts, the panel said, the plans maintained “the semblance of Hispanic voting power,” but the mapmakers actually diluted it.

Texas is covered under Section 5 of the Voting Rights Act for its history of voting discrimination. It was in court because it had to get prior approval for any changes to its voting procedures from a federal court or the Justice Department — and it could receive permission only if it could prove that the changes would not have a discriminatory effect. The judges, sensibly, said no.

As the court’s majority opinion noted, no major surgery was performed by the lawmakers on the Congressional districts of white incumbents. But there was “unchallenged evidence” that in four minority districts, the Legislature performed surgery to cut out “economic engines” and harm the districts. In a couple of cases, the Republicans cut out the district offices of the members of Congress.