The Gramm-Leach-Bliley Financial Modernization Act (GLBA), 15 U.S.C. § 6801 et seq., created privacy protections that required financial institutions to keep their customers’ information confidential. The GLBA authorized the Federal Trade Commission (FTC) (defendant) and other federal agencies to promulgate implementing regulations. The GLBA’s definition of financial institutions referenced a list of financial activities contained in the Bank Holding Company Act of 1965 (BHCA), 12 U.S.C. § 1843(k). The BHCA list incorporated a long list of nonbanking activities identified as closely related to banking by a Federal Reserve Board regulation (Regulation Y), 12 C.F.R. § 225.28, including providing services related to real-estate transactions and preparing taxes. Although neither the GLBA nor the FTC’s implementing regulations mentioned regulating the practice of law, attorneys became concerned that the FTC intended to regulate their field. The American Bar Association (ABA) (plaintiff) sent a letter to the FTC questioning the propriety of the FTC’s apparent intention to regulate the practice of law. The FTC rejected the ABA’s request to be exempted from regulation and identified the GLBA as the source of the FTC’s claimed power to regulate attorneys. The ABA brought an action against the FTC in federal district court, seeking a judicial determination that the FTC lacked statutory authority to regulate the practice of law. The district court granted summary judgment to the ABA. The FTC appealed, arguing that any institution engaged in financial activity as defined in the BHCA was a financial institution subject to the GLBA.