If there was any doubt that Chief Justice John Roberts Jr. is the pivotal vote on the U.S. Supreme Court, he erased it Thursday, the last sitting of the court’s term.

In Rucho v. Common Cause, Roberts held fast to his longstanding position that refereeing disputes over partisan gerrymandering is not the business of federal courts. It was a 5-4 decision that reflected his view that the Supreme Court has “no commission to allocate political power.”