Which precedent did the Supreme Court establish in Marbury v. Madison?

The Supreme Court established the precedent of judicial review in the landmark case of Marbury v. Madison in 1803. Judicial review is the power of the courts to examine the actions of the legislative and executive branches of government and to determine whether such actions are consistent with the Constitution. If the courts find that a law is unconstitutional, they have the power to invalidate it.

In Marbury v. Madison, the court, led by Chief Justice John Marshall, ruled that an act of Congress that was in conflict with the Constitution was not law and therefore was void and of no effect. This case established the principle that the Supreme Court had the final authority in interpreting what the Constitution means and solidified the judiciary as an equal branch of the government with a crucial role in checking and balancing the powers of the other branches.