((a)) Any person subject to any order issued under this subchapter may file with the Secretary a petition stating that any such order or any provision of such order or any obligation imposed in connection therewith is not in accordance with law and requesting a modification thereof or an exemption therefrom. The petitioner shall thereupon be given an opportunity for a hearing on the petition, in accordance with regulations issued by the Secretary. After such hearing, the Secretary shall make a ruling on the petition, which shall be final if in accordance with law.

((b)) The district courts of the United States in any district in which such person is an inhabitant or carries on business are hereby vested with jurisdiction to review such ruling, if a complaint for that purpose is filed within twenty days from the date of the entry of such ruling. Service of process in such proceedings may be had on the Secretary by delivering a copy of the complaint to the Secretary. If the court determines that such ruling is not in accordance with law, it shall remand such proceedings to the Secretary with directions either (1) to make such ruling as the court shall determine to be in accordance with law, or (2) to take such further proceedings as, in its opinion, the law requires.