The Supreme Court on Thursday handed an unexpected victory to Black Alabamians who had challenged the state's new congressional map for diluting their voting power, with two of the court's conservatives teaming up with the liberal minority to lay down a key marker for Section 2 of the Voting Rights Act.

The surprise 5-4 decision was written by Chief Justice John Roberts Jr. He was joined by Justice Brett Kavanaugh, a fellow Republican appointee, and the court's three liberal justices to form a majority over the dissents of the four remaining conservatives.