In the case of United States v. Lopez, the majority offered the explanation that the Gun-Free School Zones Act of 1990, which made it a federal offense to possess a firearm in a school zone, exceeded Congress's power under the Commerce Clause of the United States Constitution. The majority argued that the Act did not have a substantial effect on interstate commerce and therefore could not be justified under Congress's authority to regulate interstate commerce. According to the majority, the regulation of firearms in a school zone was a matter traditionally left to the states, rather than the federal government. This decision was significant as it marked a limitation on the scope of Congress's commerce power.
