The United States Marshals Service (USMS) is a U.S. federal law enforcement agency within the U.S. Department of Justice (see 28 U.S.C. § 561). The office of U.S. Marshals is the oldest American federal law enforcement agency. The U.S. Marshals office was created by the Judiciary Act of 1789. The Marshals Service is part of the executive branch of government, and is the enforcement arm of the U.S. federal courts. The U.S.