What were John Marshall's biggest contributions to American society?

John Marshall’s biggest contribution to American society was as Chief Justice of the United States Supreme Court. He served in this capacity for an astonishing 34 years, right up until his death. To date, Marshall is the longest-serving Chief Justice in American history.
Before Marshall was appointed Chief Justice, the Supreme Court was very much a minor player in the American system of government, wholly unequal to the executive and legislative branches. But that all changed in 1803, with the landmark Supreme Court decision of Marbury v Madison. Under Marshall’s astute leadership, the Court gave itself the power to strike down laws and government actions it deemed to be unconstitutional. This is what’s known as judicial review. Though immensely controversial at the time, and remaining so ever since, this decision elevated the judicial branch to parity with the executive and the legislature, making it a strong and essential part of the American system of government.
John Marshall, in his role as Chief Justice, was more responsible for this ground-breaking development in American legal, political, and constitutional history than any other individual. His abiding legacy is a judicial branch that, though never far from controversy, is nonetheless a vitally important element in American public life.