The Supreme Court has blocked a lower-court ruling in a redistricting dispute in North Dakota that would gut a landmark federal civil rights law for millions of people.

The U.S. Supreme Court agreed to prolong a temporary freeze on North Dakota’s legislative district map — hinting that the justices may be interested in hearing a tribal voting rights case against the state.

The Supreme Court blocked an appeals court ruling that would gut a key provision of the Voting Rights Act in a case brought by Native American tribes challenging a North Dakota legislative map.