Alfonso Lopez , Ir . , a 12 th-grade student at Edison High School in San Antonio Texas went to school carrying a concealed 38 - caliber handgun and five bullets School officials , acting on an anonymous tip , confronted Lopez . Lopez admitted that he had the gun . He was arrested and charged with violation of Federal law , the Gun - Free School Zones Act of 1990 . Lopez moved to dismiss his indictment on the grounds that the provision of the Gun-Free School Zones Act with which he was charged was unconstitutional in that it was beyond the power of Congress to legislate controls over public schools . The district court found the statute to be a constitutional exercise of congressional authority . Lopez was found guilty and sentenced to two years in prison . He appealed and challenged his conviction on the basis of the commerce clause . The Court of Appeals agreed with Lopez , found the Gun - Free School Zones Act an unconstitutional exercise of congressional authority , and reversed the conviction . The U.S . Attorney appealed . Who should win at the U.S . Supreme Court and why