Which landmark case established the principle of judicial review?

The landmark case that established the principle of judicial review is Marbury v. Madison. This case, decided in 1803, is pivotal in U.S. legal history as it was the first time the Supreme Court asserted the power to declare an act of Congress unconstitutional. The ruling provided the courts with the authority to interpret the Constitution and ensured that the judiciary could check the powers of the other branches of government.

The origin of this principle lies in the case's background, where William Marbury was denied his commission to become a justice of the peace, leading him to sue Secretary of State James Madison. Chief Justice John Marshall’s decision articulated that it was the duty of the judicial system to say what the law is and that any law contrary to the Constitution is void. This fundamental principle of judicial review allows the Supreme Court to maintain the supremacy of the Constitution and is a cornerstone of the American legal system.