7 U.S.C. § 6208: Investigations and power to subpoena

for the effective carrying out of the responsibilities of the Secretary under this chapter; or to determine whether a person subject to the provisions of this chapter has engaged or is engaging in any act that constitutes a violation of any provision of this chapter, or any order, rule, or regulation issued under this chapter. For the purpose of an investigation made under subsection (a), the Secretary may administer oaths and affirmations and may issue a subpoena to require the production of any records that are relevant to the inquiry. The production of any such records may be required from any place in the United States. For the purpose of an administrative hearing held under section 6206 or 6207 of this title, the presiding officer is authorized to administer oaths and affirmations, subpoena witnesses, compel their attendance, take evidence, and require the production of any records that are relevant to the inquiry. Such attendance of witnesses and the production of any such records may be required from any place in the United States. In case of contumacy by, or refusal to obey a subpoena to, any person, the Secretary may invoke the aid of any court of the United States within the jurisdiction of which such investigation or proceeding is carried on, or where such person resides or carries on business, in order to enforce a subpoena issued by the Secretary under subsection (b). The court may issue an order requiring such person to comply with such a subpoena. Any failure to obey such order of the court may be punished by such court as a contempt thereof. Process in any such case may be served in the judicial district of which such person resides or conducts business or wherever such person may be found. The site of any hearings held under section 6206 or 6207 of this title shall be within the judicial district where such person is an inhabitant or has a principal place of business.