United States v. Alfonso D. Lopez, Jr., 514 U.S. 549 (1995), was a landmark case of the United States Supreme Court concerning the Commerce Clause. It was the first case since 1937 in which the Court held that Congress had exceeded its power to legislate under the Commerce Clause. In his dissent, Associate Justice Stephen Breyer argued that Congress could regulate handgun possession under the Commerce Clause because gun violence could have a significant effect on interstate commerce by impairing educational environments.