The Supreme Court on Monday threw out a North Carolina court ruling that upheld Republican-drawn electoral districts for state and congressional lawmakers.

The justices ordered the state Supreme Court to consider anew whether the North Carolina legislature relied too heavily on race when it redrew voting districts following the 2010 census.

The high court issued a similar ruling last month involving a complaint from black Alabama Democrats that the Republican-dominated legislature illegally packed black voters into too few voting districts.

In Alabama, the justices said a lower court used the wrong test when it upheld legislative districts and determined that race was not the primary motivating factor in drawing boundary lines.

The Supreme Court said judges in North Carolina must revisit their ruling in light of the Alabama decision.

In both states, Republicans strengthened their grip on power through redistricting.

Election and civil rights advocacy groups and Democratic voters in North Carolina sued over the maps and argued that lawmakers created oddly shaped districts to create clusters of Democratic-leaning black voters. The redrawing of the map had the effect of benefiting Republicans elsewhere in the state. Republicans said the districts were lawful and designed to protect the state from legal claims under the federal Voting Rights Act.