Judicial review is the power of courts to assess whether a law, executive action, or other governmental act conforms to a written constitution, and to refuse to enforce acts found inconsistent with it. In the United States, the term most commonly refers to the authority of federal courts, and ultimately the United States Supreme Court, to invalidate legislation or executive conduct that conflicts with the Constitution of the United States. The precise scope of this power-how aggressively courts should exercise it, and what interpretive methods should guide its use-is contested; see Constitutional Interpretation and the viewpoints below.
Judicial review is exercised by federal and state courts throughout the United States and is a well-established feature of American constitutional government. The Supreme Court asserted this power for federal courts over acts of Congress in *Marbury v. Madison* (1803), though the Constitution's text does not explicitly grant it. Courts at all levels routinely consider constitutional challenges to statutes and government action, and Supreme Court decisions on such questions are treated as binding precedent unless later overruled.
The practice remains debated on several fronts: the legitimacy and proper limits of judicial review relative to the elected branches (the Administrative State and Separation of Powers), the interpretive methods judges should use, and historical episodes-such as the Roosevelt Court-Packing Plan and the broader Court Packing 1937 - Debate-in which the scope or composition of the reviewing court itself became a matter of political contest. For historical development, see Judicial Review - History.