Marbury v. Madison, legal case in which, on February 24, 1803, the U.S. Supreme Court first declared an act of Congress unconstitutional, thus establishing the doctrine of judicial review. The court's opinion, written by Chief Justice John Marshall, is considered one of the foundations of U.S. constitutional law.
The issue directly presented by Marbury v. Madison can only be described as minor. By the time the court heard the case, the wisdom of Jefferson's desire to reduce the number of justices of the peace had been confirmed (and the Judiciary Act of 1801 had been repealed) Marbury's