Marbury v. Madison was a landmark case in which the United States Supreme Court asserted its authority to review acts of Congress and determine their compliance with the Constitution. This case arose from a conflict during the transition between Presidents John Adams and Thomas Jefferson. At the end of his presidency, Adams appointed several judges, including William Marbury, but many of their commission papers were not delivered before Jefferson took office. Jefferson's new Secretary of State, James Madison, refused to deliver the commissions, leading Marbury to petition the Supreme Court for a writ of mandamus to compel the delivery of his commission.

The Court, led by Chief Justice John Marshall, faced a significant dilemma: if it ruled in favor of Marbury, there was a risk that Jefferson and Madison would ignore its ruling, which could undermine the authority of the Court. Conversely, denying Marbury's request could also weaken the Court's standing. In a carefully crafted decision, Marshall ruled that while Marbury was entitled to his commission, the provision of the Judiciary Act of 1789 that granted the Court the power to issue such a writ was unconstitutional. Thus, the Court established the doctrine of judicial review, asserting its authority to nullify laws that are in conflict with the Constitution.

This pivotal moment not only established the judiciary as an equal branch of government but also set a precedent for the expanded role of the Supreme Court in American government. By declaring an act of Congress unconstitutional, the Court positioned itself as a check on legislative powers, ensuring that all laws adhered to constitutional principles. The implications of this decision reverberated through U.S. history, influencing numerous future court cases and solidifying the judiciary's integral role in American democracy.