appropriate district court of the United States. (d) Additional remedies The remedies provided in this Act shall be in addition to, and not exclusive of, other remedies that may be available. 10. Investigation and power to subpoena (a) Investigations The Secretary may conduct such investigations as the Secretary considers necessary for the effective administration of this Act, or to determine whether any person has engaged or is engaging in any act that constitutes a violation of this Act or any order or regulation issued under this Act. (b) Subpoenas, oaths, and affirmations (1) Investigations For the purpose of conducting an investigation under subsection (a) , the Secretary may administer oaths and affirmations, subpoena witnesses, compel the attendance of witnesses, take evidence, and require the production of any records that are relevant to the inquiry. The production of the records may be required from any place in the United States. (2) Administrative hearings For the purpose of an administrative hearing held under section 8(a)(2) or section 9(c)(4) , the presiding officer may administer oaths and affirmations, subpoena witnesses, compel the attendance of witnesses, take evidence, and require the production of any records that are relevant to the inquiry. The attendance of witnesses and the production of the records may be required from any place in the United States. (c) Aid of courts (1) In general In the case of contumacy by, or refusal to obey a subpoena issued under subsection (b) to, any person, the Secretary may invoke the aid of any court of the United States within the jurisdiction of which the investigation or proceeding is conducted, or where the person resides or conducts business, in order to enforce a subpoena issued under subsection (b) . (2) Order The court may issue an order requiring the person referred to in paragraph (1) to comply with a subpoena referred to in paragraph (1) . (3) Failure to obey Any failure to obey the order of the court may be punished by the court as a contempt of