Any such oath, affirmation, affidavit, or examination, when certified under the hand of any such employee by whom it was administered or taken and authenticated by the seal of the Department, may be offered or used in any court of the United States and without further proof of the identity or authority of such employee shall have like force and effect as if administered or taken before a clerk of such court.

In case of disobedience to any such subpoena, the aid of any district court of the United States may be invoked in requiring the attendance and testimony of witnesses and the production of documentary evidence, and such court within the jurisdiction of which the inquiry is carried on may, in case of contumacy or refusal to obey a subpoena issued to any officer, agent, or employee of any corporation or to any other person, issue an order requiring such corporation or other person to appear or to give evidence touching the matter in question; and any failure to obey such order of the court may be punished by such court as a contempt thereof.