49 U.S.C. § 525: Disobedience to subpoenas

A motor carrier, motor carrier of migrant workers, or motor private carrier not obeying a subpoena or requirement of the Secretary of Transportation under this chapter to appear and testify or produce records shall be fined at least $1,000 but not more than $10,000, imprisoned for not more than one year, or both. The Secretary may withhold, suspend, amend, or revoke any part of the registration of a person required to register under chapter 139 for failing to obey a subpoena or requirement of the Secretary under this chapter to appear and testify or produce records.