What principle was established by the Supreme Court case Marbury v. Madison?

The principle established by the Supreme Court case Marbury v. Madison is judicial review. This landmark decision, delivered in 1803 by Chief Justice John Marshall, asserted the power of the Supreme Court to review and invalidate laws and actions of Congress and the President that are found to be unconstitutional.

Judicial review is significant because it allows the judiciary to uphold the Constitution as the supreme law of the land, ensuring that no law or act can contravene the constitutional framework. This power has enabled the courts to act as a check on legislative and executive branches, thus maintaining the rule of law and protecting individual rights against legislative overreach. The establishment of this principle has had a lasting impact on the balance of power within the American government and has shaped the role of the judiciary in interpreting the law.