Judicial Review became a precedent because of the landmark case Marbury v. Madison
. This case established the right of the Judicial Branch of the government to declare a law unconstitutional. John Marshall
, Chief Justice of the Supreme Court ruled that the portion of the Judiciary Act of 1789 allowing for the Writ of Mandamus was unconstitutional. This decision helped put the Judicial Branch on a more even footing with the Legislative Branch and later the Executive Branch as its power has grown of the years.