National Geographic Style Manual has moved to
The official title of the presiding judge of the U.S. Supreme Court is chief justice of the United States, not chief justice of the Supreme Court. Capitalize as a title when it immediately precedes a personal name; otherwise lowercase, including appositives.
The chief justice heads the entire federal judiciary, not just the Supreme Court:
Chief Justice John Roberts
Associate Justice of the Supreme Court Ruth Bader Ginsburg
Associate Justice Ginsburg
the associate justice