United States v. Lopez

In United States v. Lopez, 514 U.S. 549 (1995), the U.S. Supreme Court rejected the argument that Congress could regulate social activities merely if they are related to the economic productivity of its citizenry. The vote was 5-4, with Chief Justice William Rehnquist writing the majority opinion and Justices Stephen Breyer, John Paul Stevens, David Souter, and Ruth Bader Ginsburg all dissenting.

The Court invalidated the Gun-Free School Zones Act of 1990, which made it a federal offense "for any individual knowingly to possess a firearm at a place that the individual knows, or has reasonable cause to believe, is a school zone."

The Court rejected an argument that enhancing “productivity” would justify federal regulation of social activities. The Court rejected this argument in part because that would justify federal regulation of “family law (including marriage, divorce, and child custody),” which the Court would not allow. 514 U.S. at 564.

This decision became the leading precedent for rulings against the federal government in favor of federalism or "states' rights."