Police Officer K.I. Fromme stopped and attempted to frisk John H. Hill, Jr. (defendant). The detention was illegal because Fromme was acting only on an anonymous tip and had no other reason to suspect Hill of illegal conduct. Hill resisted the frisk and hit Fromme. Other police officers arrived on the scene and subdued Hill. The Commonwealth of Virginia (plaintiff) successfully prosecuted Hill for assault and battery of a law-enforcement officer. Hill appealed his conviction to the Virginia Court of Appeals, which ruled that Hill had a right to use reasonable force in resisting an illegal detention and reversed the conviction. The Commonwealth appealed to the Supreme Court of Virginia.