In American Constr. Co. v. Jacksonville, T. & K. W. R. Co., 148 U. S. 372 (1893), a judgment of the Circuit Court of Appeals was challenged because one member of that court had been prohibited by statute from taking part in the hearing and decision of the appeal. The Supreme Court succinctly observed: "If the statute made him incompetent to sit at the hearing, the decree in which he took part was unlawful, and perhaps absolutely void, and should certainly be set aside or quashed by any court having authority to review it by appeal, error or certiorari." 148 U. S., at 387. The American Constr. Co. rule was again applied in William Cramp & Sons Ship & Engine Building Co. v. International Curtiss Marine Turbine Co., 228 U. S. 645 (1913), even though the parties had consented in the Circuit Court of Appeals to the participation of a District Judge who was not permitted by statute to consider the appeal. Id., at 650. Rather than sift through the underlying merits, we remanded to the Circuit Court of Appeals "so that the case may be heard by a competent court, [organized] conformably to the requirements of the statute." Id., at 651.