United States v. Lopez, legal case in which the U.S. Supreme Court on April 26, 1995, ruled (5–4) that the federal Gun-Free School Zones Act of 1990 was unconstitutional because the U.S. Congress, in enacting the legislation, had exceeded its authority under the commerce clause of the Constitution.

A high school senior was convicted for bringing a gun to his school, which Congress made a federal crime under the Gun Free School Zones Act.

UNITED STATES, PETITIONER v. ALFONSO LOPEZ, Jr. on writ of certiorari to the united states court of appeals for the fifth circuit [April 26, 1995] Chief Justice Rehnquist delivered the opinion of the Court.. Following is the case brief for United States v. Lopez, 132 S. Ct. 945 (2012). The Fifth Circuit Court of Appeals reversed the conviction, finding that the federal law was unconstitutional. In United States v.Lopez (1995), the United States Supreme Court declared the Gun-Free School Zones Act of 1990 an unconstitutional overreach of the implied powers of Congress under the Commerce Clause.The 5-4 divided decision preserved the system of federalism and reversed the Supreme Court’s 50-year trend of rulings that expanded the powers of Congress.