10. John Marshall
John Marshall was an important figure in the administrations of George Washington and John Adams, serving as the latter’s Secretary of State before being appointed to the Supreme Court. In 1803 Marshall led the court to its decision in the case known as Marbury vs. Madison, which established the principle of judicial review and the authority of the Supreme Court to prevent states and the federal government from implementing laws which violate the Constitution. Marshall’s decision established the Supreme Court as an independent but equal branch of the government. He remains the Chief Justice with the longest tenure on the court in American history.