Skip to main content

United States v. Lopez


UNITED STATES V. LOPEZ, 514 U.S. 549 (1995), curtailed congressional regulatory authority under the Commerce Clause (U.S. Constitution, Article 1, section 8) and called into question the post-1937 understanding of judicial review and the separation of powers. From 1880 through 1937, the Supreme Court had often restrained congressional commerce power, relying on an artificial distinction between "manufacturing" and "commerce," as well as a supposed state sovereignty acknowledged by the Tenth Amendment. After 1937, however, the Court seemingly authorized unrestricted congressional power to regulate economic matters under its commerce power.

Chief Justice William H. Rehnquist's opinion for a 5-4 majority in Lopez therefore came as a surprise, holding unconstitutional the federal Gun-Free School Zones Act on the grounds that school violence did not "substantially affect" interstate commerce. The majority relied on a distinction between "commercial" and "noncommercial" activity to delineate federal power. Justice Clarence Thomas, concurring, tried to disinter the manufacturing-commerce distinction. The dissenting justices would have upheld the statute, finding an adequate connection between interstate commerce and the effects of school violence.

United States v. Morrison (2000) confirmed the assumption that Lopez signaled a significant departure from previous commerce clause precedent. In striking down the federal Violence Against Women Act, Chief Justice Rehnquist for the same 5-4 majority extended the doctrine of Lopez to distinguish "truly national" from "truly local" activities. He ignored a former criterion that relied on the aggregate effects of the regulated activity and thereby seemed to be returning to a pre-1937 understanding of the commerce clause.


Lessig, Lawrence. "Translating Federalism: United States v. Lopez." Supreme Court Review 5 (1996): 125–215.

Tribe, Laurence H. American Constitutional Law. 3d ed. Mineola, N.Y.: Foundation Press, 2000.

William M.Wiecek

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"United States v. Lopez." Dictionary of American History. . 23 Mar. 2018 <>.

"United States v. Lopez." Dictionary of American History. . (March 23, 2018).

"United States v. Lopez." Dictionary of American History. . Retrieved March 23, 2018 from

Learn more about citation styles

Citation styles gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, cannot guarantee each citation it generates. Therefore, it’s best to use citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.