WASHINGTON (Reuters) - The U.S. Supreme Court sided with Republicans in Texas and North Carolina on Monday in two more cases on the contentious issue of politicians manipulating electoral district boundaries for political gain, known as gerrymandering.

Trees cast shadows outside the U.S. Supreme Court in Washington, U.S., June 25, 2018. REUTERS/Toya Sarno Jordan

The justices upheld a batch of Republican-drawn legislative districts in Texas, including two in the U.S. House of Representatives, that had been thrown out by a lower court for diluting the power of black and Hispanic voters. The ruling was 5-4, with the conservative justices in the majority and the liberals dissenting.

Separately, the justices threw out a lower court ruling that had struck down North Carolina’s Republican-drawn U.S. House districts, directing that the decision be revisited in light of its ruling in a Wisconsin gerrymandering case last week that also preserved a Republican-drawn electoral map.

The North Carolina dispute differed from the Texas case decided on Monday in that it focused on the redrawing of electoral maps by state legislators to give one party a lopsided advantage, in this case the Republicans, rather than for racial discrimination.

The decisions will not affect the maps used for this year’s elections. Democrats have accused Republicans of escalating partisan gerrymandering this decade, helping President Donald Trump’s party maintain control of the U.S. House of Representatives and many state legislatures.

The Supreme Court last week declined to use high-profile cases from Wisconsin and Maryland to restrict partisan gerrymandering.

Its decision to send the North Carolina case back to the lower court indicates the justices are no closer to delivering a comprehensive ruling on whether courts can curb partisan gerrymandering when it is done in such an extreme way that it deprives certain voters of their constitutional rights.

Civil rights activists decried the Texas ruling, in part because it comes just before the once-every-decade redistricting process is set to begin again in 2020.

“A clear message should be sent that racial discrimination has no place in the redistricting process. Unfortunately, the Supreme Court fell short,” said Kristen Clarke, executive director of the Lawyers’ Committee for Civil Rights Under Law.

The Supreme Court for decades has invalidated state electoral maps due to racial discrimination but has been reluctant to intervene over district boundaries drawn purely for partisan advantage.

The court ruled in the Texas case that the challengers had not done enough to show that the Republican-led Texas legislature acted with discriminatory intent when it adopted new electoral maps in 2013 for state legislative and U.S. House seats. The court did rule, however, that one of the eight challenged state legislature districts was unlawful.

Trump’s administration had backed Texas in the case.

The high court last year put on hold lower court rulings that had invalidated various Texas electoral districts.

‘LEGAL ERROR’

In Monday’s ruling, conservative Justice Samuel Alito said the lower court had “committed a fundamental legal error” in analyzing the dispute. Liberal Sonia Sotomayor, the court’s only Hispanic justice, fired back in a dissenting opinion.

“It means that, after years of litigation and undeniable proof of intentional discrimination, minority voters in Texas - despite constituting a majority in the state - will continue to be underrepresented in the political process,” Sotomayor wrote.

In the North Carolina case, the high court had previously put on hold the lower court’s order that a new map be drawn.

The three-judge panel in Greensboro, North Carolina ruled unanimously in January that the Republican-drawn map of North Carolina’s 13 U.S. House districts violated the constitutional guarantee of equal protection under the law. Two of the judges found it also ran afoul of the Constitution by discriminating based on political belief and association.

Critics have said gerrymandering is becoming more extreme through the use of precise voter data and computerized modeling to devise maps that dilute the clout of voters who tend to favor the party not in power. Critics in both parties have said gerrymandering distorts democracy by stifling large segments of the electorate.

On June 11, the Supreme Court also revived Ohio’s policy of purging infrequent voters from registration rolls, a ruling that detractors called another blow to voting rights.