delivered the opinion of the Court:

The claim of relator to intervene in the interference between Forsyth and Clark is based upon its alleged ownership of the Forsyth invention, the title to which had been adjudged in relator by the decision of Judge Day in the suit in the United States district court in Ohio. To grant the writ, it would be necessary to require the Commissioner to set aside the award of priority to Clark and reopen the proceedings to permit relator to intervene and contest the interference according to the procedure of the Patent Office. Delator, during the existence of this interference, was in privity with Forsyth, as the equitable owner, at least, of the Forsyth invention. Delator made application to the Commissioner for leave to intervene, which was denied. Hence relator is not here seeking to compel the Commissioner to make a decision commanded by law, but to compel him to reverse a decision duly made in the discharge of his official duty. The decision, though it may be erroneous, cannot be reviewed in this proceeding.

The writ is sought also for the purpose of compelling the Commissioner to declare an interference in favor of relator. Section 4904, U. S. Dev. Stat. U. S. Comp. Stat. 1901, p. 3389, provides: “Whenever an application is made for a patent which, in the opinion of the Commissioner, would interfere with any pending application, or with any imexpired patent, he shall give notice thereof to the applicants, or applicant and patentee, as the case may be, and shall direct the Primary Examiner to proceed to determine the question of priority of invention. And the Commissioner may issue a patent1 to the party who is adjudged the prior inventor, unless the adverse party *183appeals from the decision of the Primary Examiner, or of the board of Examiners in Chief, as the case may be. within such time, not less than twenty days, as the Commissioner shall prescribe.”

The determination of the existence of an interference is confided by statute to the judgment and discretion of the Commissioner of Patents; and whether in the exercise of that judgment in the present case he was right or wrong, the conclusion was a possible one, and is not subject to review by mandamus. United States ex rel. Ness v. Fisher, 223 U. S. 683, 56 L. ed. 610, 32 Sup. Ct. Rep. 356.

Since the patent has been issued to Clark, relator has a double remedy,—one for infringement, and a special remedy provided by sec. 4918, U. S. Rev. Stat. U. S. Comp. Stat. 1901, p. 3394. Indeed, it may well be that relator has still an avenue of procedure open in the Patent Office thrpugh which he could reopen the proceedings in such manner as to reserve the questions here presented for consideration on appeal from a decision of the Commissioner. The writ of mandamus, however, cannot be substituted for an appeal or writ of error.

Neither are we impressed with the contention of counsel for relator, to the effect that the writ should be issued to compel the Commissioner to recognize and give effect to the decision of Judge Day. In the remedies open to relator, that adjudication can be availed of in so far as it may be beneficial to it. The Commissioner acts in these matters in a quasi judicial capacity, and while he may err in not following the adjudications of a certain question by the courts, his judgment cannot be controlled by mandamus simply because it is in conflict with the decision of a court.

The judgment is affirmed, with costs. Affirmed.