An order issued by the Administration under this section shall be final and conclusive unless within thirty days after the service thereof the licensee, or other person against whom an order is issued, appeals to the United States court of appeals for the circuit in which such licensee has its principal place of business by filing with the clerk of such court a petition praying that the Administration’s order be set aside or modified in the manner stated in the petition. After the expiration of such thirty days, a petition may be filed only by leave of court on a showing of reasonable grounds for failure to file the petition theretofore. The clerk of the court shall immediately cause a copy of the petition to be delivered to the Administration, and the Administration shall thereupon certify and file in the court a transcript of the record upon which the order complained of was entered. If before such record is filed the Administration amends or sets aside its order, in whole or in part, the petitioner may amend the petition within such time as the court may determine, on notice to the Administration. The filing of a petition for review shall not of itself stay or suspend the operation of the order of the Administration, but the court of appeals in its discretion may restrain or suspend, in whole or in part, the operation of the order pending the final hearing and determination of the petition. The court may affirm, modify, or set aside the order of the Administration. If the court determines that the just and proper disposition of the case requires the taking of additional evidence, the court shall order the Administration to reopen the hearing for the taking of such evidence, in such manner and upon such terms and conditions as the court may deem proper. The Administration may modify its findings as to the facts, or make new findings, by reason of the additional evidence so taken, and it shall file its modified or new findings and the amendments, if any, of its order, with the record of such additional evidence. No objection to an order of the Administration shall be considered by the court unless such objection was urged before the Administration or, if it was not so urged, unless there were reasonable grounds for failure to do so. The judgment and decree of the court affirming, modifying, or setting aside any such order of the Administration shall be subject only to review by the Supreme Court of the United States upon certification or certiorari as provided in section
1254 of title
28.