Which Supreme Court case established the principle of judicial review?

The principle of judicial review was established in the landmark Supreme Court case Marbury v. Madison. This case, decided in 1803, marked a significant turning point in the balance of power within the American government. Judicial review is the authority of the Court to examine laws and actions by the executive and legislative branches and determine whether they are unconstitutional.

In Marbury v. Madison, Chief Justice John Marshall asserted that it is the duty of the judiciary to ensure that no law or act of government can violate the Constitution. The case arose when William Marbury sued Secretary of State James Madison to compel him to deliver his commission as a justice of the peace. The decision concluded that while Marbury had a right to his commission, the law that permitted him to bring his claim to the Supreme Court was itself unconstitutional, thereby establishing the key concept that the Supreme Court has the power to invalidate laws that it finds to be inconsistent with the Constitution.

This foundational ruling set a precedent for the judiciary as an equal branch of government, responsible for safeguarding the Constitution and asserting its principles against any acts contrary to it.