The Supreme Court on Tuesday declined to impose new limits on state courts reviewing certain election-related issues by ruling against Republicans in North Carolina fighting for a congressional district map that would heavily favor their candidates.

The justices ruled in a 6-3 vote that the North Carolina Supreme Court was acting within its authority in concluding that the map constituted a partisan gerrymander under the state Constitution.

In doing so, the court declined to embrace a hitherto obscure legal argument called the “independent state legislature” theory, which Republicans say limits the authority of state courts to strike down certain election laws enacted by state legislatures.