The case of Marbury v. Madison (1803) The case of Marbury v. Madison (1803) was the first time the U.S. Supreme Court declared an act of Congress to be unconstitutional. Chief Justice John Marshall relied almost exclusively on the specific language of the Constitution, saying that it was the “paramount law of the nation” and that it constrained the actions of all three branches of the national government. The whole point of a written Constitution, Marshall asserted, was to ensure that government stayed within its prescribed limits: “The powers of the Legislature are defined and limited; and [so] that those limits may not be mistaken or forgotten, the Constitution is written.” In cases where a law conflicted with the Constitution, Marshall wrote, then “the very essence of judicial duty” was to follow the Constitution. Marshall also asserted that the courts had the responsibility to understand and articulate what the Constitution means: “It is emphatically the province and duty of the judicial department to say what the law is.”