In March 1992, Alfonso Lopez, Jr., a twelfth-grade student at Edison High School in San Antonio, Texas, arrived at school carrying a concealed .38-caliber handgun and five bullets. Acting on an anonymous tip, school authorities confronted Lopez, who admitted possessing the weapon. Local police arrested him and charged him under Texas law with firearm possession on school premises.
The following day, state charges were dismissed after federal agents charged Lopez with violating the Gun-Free School Zones Act of 1990. A federal grand jury indicted him on one count of knowing possession of a firearm at a school zone. Lopez moved to dismiss the indictment, arguing that the statute exceeded Congress's power to legislate control over public schools.
The district court denied the motion, concluding that the statute was a constitutional exercise of Congress's power to regulate activities affecting commerce because the business of schools affects interstate commerce. After a bench trial, the court found Lopez guilty and sentenced him to six months' imprisonment and two years of supervised release.
Lopez appealed to the Court of Appeals for the Fifth Circuit, which reversed the conviction, holding that the statute was beyond Congress's power under the Commerce Clause. The Supreme Court granted certiorari to review the case.