Marbury v. Madison (1803)
This case was the first time that the Supreme Court declared an act of Congress (a section of the Judiciary Act of 1789) to be unconstitutional. This is an exercise of the power of judicial review—the power of the federal courts to interpret laws in light of the Constitution.
Chief Justice John Marshall explaine>d, “[T]he Constitution of the United States confirms and strengthens the principle… that a law repugnant to the Constitution is void.” Furthermore, the Supreme Court is the proper authority to decide if a law is in conflict with the Constitution. He called this responsibility “the very essence of judicial duty.” In the Federalist Papers, Alexander Hamilton discussed “the rights of the courts to pronounce legislative acts void, because contrary to the Constitution.” He explained in Federalist No. 78, “No legislative act, therefore, contrary to the Constitution, can be valid…” Although the Founders, including Hamilton, considered the courts the weakest branch of government, their power to identify and invalidate unconstitutional laws is essential to the preservation of constitutional law.