The fractured decision was a small victory for Democratic and minority groups who accused Republicans of an unconstitutional power grab in drawing boundaries that booted four Democratic incumbents from office.
Justice Anthony M. Kennedy, writing for the majority, said Hispanics do not have a chance to elect a candidate of their choosing under the plan. The vote was 5-4 on that issue.
Republicans picked up six Texas congressional seats two years ago, and the court's ruling does not seriously threaten those gains. Lawmakers, however, will have to adjust boundary lines to address the court's concerns.
On a different matter, the court ruled 7-2 that state legislators may draw new maps as often as they like, not just once a decade as Texas Democrats claimed. That means Democratic and Republican state lawmakers can push through new maps anytime there is a power shift at a state capital.
The Constitution says states must adjust their congressional district lines every 10 years to account for population shifts. In Texas the boundaries were redrawn twice after the 2000 census, first by a court, then by state lawmakers in a second round promoted by DeLay after Republicans took control.
That was acceptable, the justices said.
"We reject the statewide challenge to Texas redistricting as an unconstitutional political gerrymander," Kennedy wrote.
However, he said the state's redrawing of District 23 violated the Voting Rights Act.
"You can say the Democrats won because any help on political matters from this conservative court has to be considered a surprise. Or you can say the Republicans won because the vast majority of the plan was upheld and certainly the Justices have signaled that similar plans in the future also are likely to be okay," CBS News legal analyst Andrew Cohen said.