The Supreme Court ruled on Thursday that a South Carolina congressional map accused of racial gerrymandering can stand, reversing a district court decision that struck down the lines for Rep. Nancy Mace‘s (R-SC) district.

Justice Samuel Alito wrote the 6-3 decision in Alexander v. South Carolina State Conference of the NAACP, finding that South Carolina’s Congressional District 1 did not violate the Constitution when the state’s Republican-controlled legislature enacted the map to ensure the district remained safe for Republicans. The ruling creates a higher bar for determining when a map can be considered a racial gerrymander, rather than a partisan gerrymander.