In 1916, Congress enacted a federal statute that permitted banks to sell insurance in small towns. Subsequently, in 1974, Florida enacted a state statute that prohibited banks from selling insurance. In 1993, Barnett Bank of Marion County, N.A. (Barnett Bank) (plaintiff) bought a licensed Florida insurance agency and began selling insurance. Based on the Florida statute, Florida State Insurance Commissioner Bill Nelson (Commissioner) (defendant) ordered Barnett Bank to stop selling insurance. Barnett Bank filed an action for declaratory and injunctive relief in federal district court. The district court found in favor of the Commissioner, and the court of appeals affirmed. The United States Supreme Court granted certiorari.