Harlan Fiske Stone
He had been a classmate at Amherst College of future President Calvin Coolidge, and was Coolidge's only appointment to the U.S. Supreme Court. Rather than serving as a conservative jurist one might expect from President Coolidge, Justice Stone became a loyal supporter of President Franklin Delano Roosevelt's New Deal. He was rewarded when President Roosevelt elevated him to be Chief Justice when that vacancy occurred.
Justice Stone's most influential opinion for the Court was United States v. Carolene Products Co., 304 U.S. 144 (1938), in which he penned a "footnote 4" that became increasingly popular to justify judicial activism with respect to social issues.