18 U.S.C. § 436: Convict labor contracts

Whoever, being an officer, employee, or agent of the United States or any department or agency thereof, contracts with any person or corporation, or permits any warden, agent, or official of any penal or correctional institution, to hire out the labor of any prisoners confined for violation of any laws of the United States, shall be fined under this title or imprisoned not more than three years, or both.