In Marbury v. Madison, the Supreme Court declared an act of Congress unconstitutional for the first time, forming the basis of judicial review in the United States.

Marbury v. Madison, 5 U.S. 137 (1803), was a landmark decision of the U.S. Supreme Court that established the principle of judicial review, meaning that American courts have the power to strike down laws and statutes they find to violate the Constitution of the United States. Decided in 1803, Marbury is regarded as the single most important decision in American constitutional law. It established that the U.S. Constitution is actual law, not just a statement of political principles and ideals. It also helped define the boundary between the constitutionally separate executive and judicial branches of the federal government.

The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that turn on questions of U.S. constitutional or federal law. It also has original jurisdiction over a narrow range of cases, specifically "all Cases affecting Ambassadors, other public Ministers and Consuls, and those in which a State shall be Party." In 1803, the court asserted itself the power of judicial review, the ability to invalidate a statute for violating a provision of the Constitution via the landmark case Marbury v. Madison. It is also able to strike down presidential directives for violating either the Constitution or statutory law.

An act of Congress is a statute enacted by the United States Congress. Acts may apply only to individual entities, or to the general public. For a bill to become an act, the text must pass through both houses with a majority, then be either signed into law by the president of the United States, be left unsigned for ten days while Congress remains in session, or, if vetoed by the president, receive a congressional override from 2⁄3 of both houses.