What legal principle was established in the case of United States v. Lopez?

The case of United States v. Lopez is pivotal in constitutional law as it marked a significant limitation on federal authority under the Commerce Clause. In this 1995 decision, the Supreme Court ruled that Congress had overstepped its bounds by enacting the Gun-Free School Zones Act of 1990, which prohibited the possession of firearms in school zones. The Court determined that such an activity did not substantially affect interstate commerce, thereby asserting that the federal government could not regulate this behavior under the Commerce Clause.

This case is notable because it was one of the first instances since the New Deal era where the Supreme Court curtailed the expansion of federal powers, signaling a shift toward a more defined boundary between federal and state jurisdiction. The ruling reinforced the principle of federalism by upholding the rights of states to regulate activities that do not have a significant impact on interstate commerce, emphasizing the limits of federal legislative power. This decision has since been used as a precedent in subsequent cases to argue against federal overreach and to advocate for the preservation of state authority in areas traditionally governed by state law.