United States v. Lopez

United States v. Lopez, 514 U.S. 549 (1995), is a landmark United States Supreme Court decision interpreting the Commerce Clause of Article I, Section 8, Clause 3 of the U.S. Constitution. Writing for a 5–4 majority, Chief Justice William Rehnquist held that the Gun-Free School Zones Act of 1990, which criminalized possession of a firearm within 1,000 feet of a school, exceeded Congress's authority to regulate interstate commerce. The case is historically significant because it marked the first time since NLRB v. Jones & Laughlin Steel Corp. (1937) — the start of the post-New Deal expansion — that the Court invalidated a federal statute on the ground that it transgressed the outer limits of the commerce power. Alfonso Lopez Jr., a twelfth-grade student in San Antonio, Texas, had been convicted under the Act; the Court reversed.

The majority synthesized prior doctrine into three categories of activity Congress may regulate under the Commerce Clause: (1) the use of the channels of interstate commerce; (2) the instrumentalities of interstate commerce, or persons and things in interstate commerce; and (3) activities that "substantially affect" interstate commerce. The Court reasoned that mere possession of a gun in a school zone fell into none of these. It was a criminal statute that "by its terms has nothing to do with commerce or any sort of economic enterprise." The Court rejected the government's argument that gun violence affects education and thereby the national economy, warning that accepting such reasoning would convert the commerce power into a general police power and leave no activity beyond federal reach — collapsing the distinction between national and local concerns essential to federalism. Justice Anthony Kennedy concurred, and Justice Clarence Thomas wrote separately urging reconsideration of the "substantial effects" test. Justices Breyer, Stevens, Souter, and Ginsburg dissented.

Lopez inaugurated what scholars call the Rehnquist Court's "New Federalism" or "federalism revolution," reasserting state sovereignty as a limit on enumerated federal powers. It was reinforced by United States v. Morrison (2000), which struck down the civil-remedy provision of the Violence Against Women Act on the same non-economic-activity rationale. The doctrine was later tested and partly distinguished in Gonzales v. Raich (2005), upholding federal regulation of homegrown medical marijuana as part of a broader economic scheme, and in NFIB v. Sebelius (2012), where Chief Justice Roberts invoked Lopez's logic to hold that the Commerce Clause does not permit Congress to compel inactivity into commerce (the individual mandate), though it survived under the taxing power. As of 2026 Lopez remains binding precedent and a foundational marker of Commerce Clause limits.

For the FSOT and U.S. Government sections of civil-service examinations, Lopez is tested in the federalism and judicial-review portions. Typical question angles ask candidates to identify it as the first modern limit on the Commerce Clause, to recall the three-category framework, to pair it with Morrison and contrast it with Raich, or to distinguish "economic" from "non-economic" activity. Examiners frequently use it to assess understanding of the enumerated-powers principle and the balance between national authority and state police powers.