In the case of United States v. Lopez, decided in 1995, the Supreme Court addressed the limits of federal power under the Commerce Clause. Alfonso Lopez, a high school student, was charged for carrying a firearm on school grounds, violating the Gun-Free School Zones Act of 1990. He argued that the federal government did not have the authority to regulate this activity. The Supreme Court ruled in a 5-4 decision that the Gun-Free School Zones Act exceeded Congress's authority under the Commerce Clause. The Court emphasized that carrying a gun in a school zone did not substantially affect interstate commerce, thus reinforcing the principle of federalism and state powers.