Opinion of the Court. 235 U.S. Federal Constitution, must be by subsequent legislation, and no mere change in judicial decision will amount to such deprivation. Ross v. Oregon, 227 U. S. 150, 161; Moore-Mansfield Construction Company v. Electrical Installation Company, 234 U. S. 619, 624; and cases cited on p. 625. An examination of the record shows that the Federal right set up in the Court of Common Pleas, and considered in the Circuit Court, the latter judgment being affirmed by the Supreme Court without opinion, concerned an alleged change of decision in the Supreme Court of Ohio, construing a statute concerning the contract upon which the railroad companies relied, the effect of which, it was alleged, would be to do violence to the contract clause of the Federal Constitution. It was not set up that subsequent legislation had impaired the obligation of the contract of the railroad companies. Therefore, in the light of the decisions of this court above quoted, no Federal right was alleged to be impaired within the meaning of the Constitution of the United States, and no such right was passed upon in the decisions of the courts. The contention is made that the presence of the Federal right set up and denied as violative of this clause of the Constitution is shown by the certificate of the Supreme Court, contained in its journal entry affirming the judgment of the Circuit Court. An examination of the certificate, however, does not show that any contention that contract rights were impaired by subsequent state legislation, was passed upon adversely to the railroad companies, but shows only that the contention was that the claim of the city, in respect to the contract of September 13, 1849, sustained by the judgment of the Circuit Court, and affirmed by the Supreme Court, was in contravention of the defendants' rights under said contract, and impaired their rights under said contract, in violation of the Constitution of the United States, particularly the tenth section of Article I thereof; "which said claims fully appear in the pleadings and record herein, and that such claims were considered by the court and decided adversely to said plaintiffs in error." The character of the claims thus made we have already described. Moreover, a mere certificate of this character cannot bring an additional question into the record, where the record does not otherwise show it to exist. Marvin v. Trout, 199 U. S. 212. It follows that the writ of error must be dismissed. MR. JUSTICE HOLMES took no part in the consideration and decision of this case. UNITED STATES v. MAYER, JUDGE OF THE DISTRICT COURT OF THE UNITED STATES FOR THE SOUTHERN DISTRICT OF NEW YORK. CERTIFICATE FROM THE CIRCUIT COURT OF APPEALS FOR THE SECOND CIRCUIT. No. 462. Argued October 22, 23, 1914. Decided November 16, 1914. While their jurisdiction is exclusively appellate, Circuit Courts of Appeals may issue writs which are properly auxiliary to their appellate power. While this court may not be required through a certificate under § 239, Judicial Code, to pass upon questions of fact or mixed questions of law and fact, or to accept a transfer of the whole case, or to answer questions of objectionable generality, a definite question of law may be submitted even if decisive of the controversy. The general principle obtains, in the absence of statute providing otherwise, that a court cannot set aside or alter its final judgment after the expiration of the term at which it was entered unless the proceeding for that purpose was begun during that term; and this case does not fall within the exceptions to that rule. Statement of the Case. 235 U. S. Whether a Federal court can grant a new trial after the end of the term is a question of power and not of procedure, and state statutes are not applicable. When a writ of error has been issued to review a judgment of conviction of the District Court in a criminal cause, the Circuit Court of Appeals has jurisdiction to issue a writ of prohibition against the District Court entering an order for new trial after expiration of the term on newly discovered evidence. When a writ of error has been issued to review its judgment of conviction in a criminal cause, the District Court has not jurisdiction, upon motion made after the term at which it was entered, to set the judgment aside and order a new trial on facts discovered after the end of the term and not appearing in the record. When a District Court has itself raised the question of its jurisdiction to entertain a motion made after expiration of the term to vacate a judgment of conviction, the consent of the United States attorney to consider the case on the merits does not confer jurisdiction, nor debar the United States from raising the question of jurisdiction, to vacate the judgment. THE facts stated in the certificate may be summarized as follows: On March 14, 1913, one Albert Freeman with two other individuals, was convicted in the District Court, Southern District of New York, on five indictments for violation of the statutes relating to the use of the mails and for a conspiracy. On that day judgments of conviction were entered and sentences were imposed as to certain of these indictments, or counts therein, sentence being suspended as to others; and on March 24, 1913, the defendant Freeman sued out a writ of error from the Circuit Court of Appeals to review the judgments of conviction. Assignments of error were filed; and on May 13, 1913, the plaintiff in error was admitted to bail by the appellate court. No bill of exceptions has been settled or filed or argument had. On January 12, 1914, the plaintiff in error gave notice of application in the District Court to set aside the judgments of conviction, and for the quashing of the indictments, or for a new trial. The grounds were, among 235 U.S. Statement of the Case. others, (1) that the defendant had been deprived of a fair trial by the misconduct of an assistant United States attorney and (2) that one juror when examined on his voir dire concealed a bias against the defendant. It is found as a fact by the District Judge, that neither the defendant nor his counsel had knowledge of the facts on which the motion was based until after the conclusion of the trial and the expiration of the term as to those counts upon which sentence had been imposed, and that these facts could not have been discovered earlier by reasonable diligence. Upon the hearing of the application, District Judge Mayer raised the question of the jurisdiction of the District Court to entertain it, in view of the fact that the term had expired. Thereupon the United States attorney submitted a memorandum tendering his consent that the application be heard upon the merits. The application was heard and District Judge Mayer handed down his decision granting a new trial, "on the ground that defendant had not had a trial by an impartial jury for the reason that one of the jurors at the time of his selection entertained a bias against the defendant resulting from the juror's observations of the conduct of the defendant and other corporate officers in relation to the production of certain corporate records before a grand jury of which he had been a member, the juror having concealed his bias on his examination on the voir dire for the purpose of securing the jury fees and the events of the trial having been such as to strengthen and confirm this bias." The order vacating the judgments of conviction and granting a new trial has not yet been entered, the District Judge having filed a memorandum stating in substance that the question of jurisdiction was an important one and that the order would be withheld until the United States attorney had an opportunity to raise the question in a higher court. Statement of the Case. 235 U.S. Thereafter, and on April 6, 1914, the United States attorney procured an order in the Circuit Court of Appeals directing District Judge Mayer to show cause why a writ of prohibition should not be issued from that court forbidding the entry of an order vacating the judgments of conviction and granting a new trial upon the ground that the District Court was without jurisdiction to enter it. Certain of the facts upon which the motion for a new trial was granted do not appear in the record of the previous trial. The questions certified are: "" QUESTION I. "A. When a writ of error has been issued to review a judgment of conviction in a criminal cause entered in a District Court and thereafter, upon a motion made in the District Court after the expiration of the term at which the judgment was entered, said District Court has indicated its intention to enter an order vacating the judgment and ordering a new trial on facts discovered after the expiration of said term and not appearing in the record of the previous trial, has the Circuit Court of Appeals jurisdiction to issue a writ of prohibition against the entry of such order by the District Court, when, in the opinion of the Circuit Court of Appeals, the District Court is without jurisdiction to enter such order? "B. Or has the Supreme Court of the United States sole jurisdiction to issue such writ of prohibition, under the circumstances above stated? "In case question I A be answered in the affirmative, then "QUESTION II. "When a writ of error has been issued to review a judgment of conviction in a criminal cause entered in a District Court, has the District Court, upon a motion made after |