delivered the opinion of the Court:
It is. conceded in the brief of counsel for appellee that “the judgments of the Primary Examiner, unappealed from, were as final as would have been the judgments of the Examiners-in-Chief on appeal, or of the Commissioner on appeal, had appeals been taken to those tribunals;” but it is contended that the judgment of the Primary Examiner dissolving the interferences on the ground that neither Thompson nor Lemp had the right to make the claims was an interlocutory, and not a final, judgment, because it did not decide the question of priority. It is true, as contended by appellee, that in several cases decided by this court prior to Podlesak v. McInnerney, 26 App. D. C. 399, it was in effect held that in interference cases the right of either party to make the claims of the issue, except under extraordinary circumstances, would not be considered. In the Podlesak Case, however, upon careful consideration we modified our earlier views, and ruled that, inasmuch as the right of a party to make a claim goes to the foundation of an interference, a judgment of the Primary Examiner denying that right might be appealed to this court, and that we would take jurisdiction to determine that question “as an ancillary question to be considered in awarding priority of invention.” The opinion states: “If it be incorrectly held that such party has a right to make the claim, priority may be awarded to him, and his adversary be deprived of a substantial right in that he is not given a claim where he necessarily is the prior inventor, his adversary never having made the invention.” Allen v. United States ex rel. Lowry, 26 App. D. C. 8, relied upon by *471appellee, in no way conflicts with the decision in the Podlesak Case. Lowry, one of the parties to the interference, was granted a patent, and an interference was subsequently declared between his patent and the application of one Spoon. Lowry moved to dissolve the interference upon the ground that Spoon’s press was inoperative, and therefore that Spoon had no right to make the claims in issue. The Primary Examiner granted the motion, and an appeal was prosecuted to the Examiners-in-Chief, who affirmed the decision. Spoon thereupon petitioned the Commissioner of Patents, who remanded the case to the Primary Examiner for further consideration, and that officer, upon the filing of additional affidavits, decided that Spoon had a right to make the claims in issue. An appeal was taken to the Board of Examiners-in-Chief, which was dismissed by that Board for the want of jurisdiction. Lowry then petitioned the Commissioner to take jurisdicton of the appeal, whch petition was denied. The supreme court of the District of Columbia was then petitioned to issue a writ of mandamus commanding the Commissioner of Patents to direct the Examiners-in-Chief to reinstate and take jurisdiction of the appeal, and the petition was granted. This court, on appeal, reversed the lower court, and our ruling was affirmed by the Supreme Court of the United States (203 U. S. 476, 51 L. ed. 281, 27 Sup. Ct. Rep. 141) the ground of both decisions being that appeals are only allowed to the Examiners-in-Chief, and from them to the Commissioner, from “final decisions, and not such as are made in interlocutory matters.” The Supreme Court quoted with approval the following from the decision of the Acting Commissioner: “It is to be particularly noted that there has been no decision as to the rival claims of the parties to this interference. It has not been decided which party is entitled to the patent. If it should at any time be decided that Spoon is entitled to the patent, Lowry will have the right of appeal, but until such final decision is rendered the statute gives him no right of appeal. It would seem upon general principles of law that Lowry could then present for determination by his appeal any question which in his opinion vitally affects the question which party is entitled to the pat*472ent. The only ground upon which he can reasonably claim the right of appeal on this motion is that the question vitally affects his claimed right to a patent, and if it does that, he can raise it at final hearing and contest it before the various appellate tribunals, including the court of appeals.” It is obvious that the decision of the Primary Examiner in the Lowry Case was-purely interlocutory, for it eliminated neither party to the interference, and deferred final judgment on the question of priority until each party had taken testimony. It was still possible, therefore, for Lowry to prevail on the merits and receive the award of priority. Neither does the case of Union Distilling Co. v. Schneider, 29 App. D. C. 1, conflict with Podlesak v. McInnerney, for the reason that the appeal in that case was taken to this court before the subject-matter in dispute had been awarded to either party.
It is further contended that because sec. 4904, Rev. Stat., provides that whenever “in the opinion of the Commissioner” an interference exists, notice shall be given the parties, etc., a nondelegable duty is imposed upon the Commissioner. This question was considered in Allen v. United States, supra, and it was there held that the Commissioner, “for any reason which he considers may be in the interest of the public or the parties,” may delegate to the Primary Examiner the duty of determining primarily whether an interference in fact exists, and that “in so doing he is not thereby depriving any party of any statutory right to have all questions passed upon at final hearing, and on appeals therefrom, which are necessary for a correct determination of the question of priority, which is the sole question for which interferences are declared.” To adopt the view of the appellee would revérse a practice which has prevailed in the Patent Office since the statute was enacted in 1870, and would in effect render the statute nugatory, since it would be a physical impossibility for the Commissioner personally to pass upon all these preliminary questions. He was given assistants for that purpose. Moreover, the Primary Examiner is skilled in the particular art, and therefore peculiarly qualified to pass upon a question involving the right of either party to make the *473claims of the issue. We think the demands of the statute fully met when it is provided that at some stage in the proceedings the personal opinion of the Commissioner may be invoked by either party.
It is next contended by the appellee that the judgment of the Primary Examiner was not a final judgment because, under the provisions of secs. 4909-4911, Rev. Stat. U. S. Comp. Stat. 1901, pp. 3390, 3391, the applicant is entitled to a reconsideration and second rejection of his claims by the Primary Examiner. These sections read as follows:
“Sec. 4909. Every applicant for a patent or for the reissue of a patent, any of the claims of which have been twice rejected, and every party to an interference, may appeal from the decision of the Primary Examiner, or of the Examiner in charge of interferences in such case, to the Board of Examiners-in-Chief; having once paid the fee for such appeal.
“Sec. 4910. If such party is dissatisfied with the decision of the Examiners-in-Chief, he may, on payment of the fee prescribed, appeal to the Commissioner in person.
“Sec. 4911. If such party, except a party to an interference, is dissatisfied with the decision of the Commissioner, he may appeal to the supreme court of the District of Columbia, sitting in banc.”
It will be necessary to examine secs. 4903 and 4904, Rev. Stat. IT. S. Comp. Stat. 1901, p. 3389, in discussing the merits of this contention. These sections read as follows:
“Sec. 4903. Whenever, on examination, any claim for a patent is rejected, the Commissioner shall notify the applicant thereof, giving him briefly the reasons for such rejection, together with such information and references as may be useful in judging of the propriety of renewing his application or of altering his specification; and if, after receiving such notice, the applicant persists in his claim for a patent, with or without altering his specifications, the Commissioner shall order a re-examination of the case.
“Sec. 4904. Whenever an application is made for a patent which, in the opinion of the Commissioner, would interfere *474with any pending application, or with any nnexpired 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 patent to the party who is adjudged the prior inventor, unless the adverse party appeals 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.”
In Allen v. United States, supra, sec. 4909 was construed “as though it read, every applicant for a patent, or for the reissue of a patent, any of the claims of which have been twice rejected, may appeal from the decision of the Primary Examiner, and every party to an interference may appeal from the decision of the Examiner in charge of interferences in such case, to the Board of Examiners-in-Chief. In other words, to abbreviate and make the section more succinct, the words ‘may appeal from the decision’ were used but once, but we think that thereby clearness was sacrificed for brevity.” This interpretation negatives the contention of appellee that the provision giving an applicant the right to have his claim twice rejected applies in inter partes cases. In an ex parte case arising under sec. 4903 the applicant in the first instance has no knowledge as to the references and reasons of the rejection by the Primary Examiner of his claim, and has no opportunity to be heard before action has been taken by that official. The notice of rejection contains his first information of what has taken place in the Patent Office. The statute therefore very properly provides in effect that upon the receipt of such notice the applicant may have an opportunity to meet the objections raised by the Primary Examiner. Under sec. 4904, however, it is made the duty of the Commissioner to give notice to parties thought to be in interference, and to “direct the Primary Examiner to proceed to determine the question of priority of invention.” The statute therefore imposes upon the Commissioner the duty of notifying the parties prior to the first hearing before the Pri*475mary Examiner so that, when the hearing is had, both parties have a right to be present, and, in the event a motion for dissolution is made, the applicant affected has knowledge of the grounds for the motion, and ample opportunity for hearing and argument. No more reason exists for a second hearing than exists for a second hearing in any other case between two parties litigant where due notice has been given and all the forms and requirements of the law have been complied with. The Commissioner in his opinion said: “I am of the opinion that the proceedings in the Thompson application since the withdrawal of the appeal to the Examiners-in-Chief in the interference were contrary to the evident spirit of the rules, and that to sustain such proceedings would be in opposition to the requirements of good practice and to the interests of applicants generally. If parties can waive their rights of inter partes appeal in the interference, and then proceed by ex parte appeals to try the same questions which they could have tried by the inter paries appeals, the provision of rule 124, that appeals shall be heard inter partes, is rendered ineffective. If the inter partes hearing upon appeal is to be escaped, the usefillness of motions for dissolution will be slight, except in those cases where parties voluntarily take the inter partes appeal. Why should motions be brought, or even permitted, if decisions granting them can be set aside upon appeal without opportunity for the moving parties to be heard, and, presumably to a large extent, without consideration of the arguments upon which the conclusions appealed from are based? It is no sufficient answer to say that if the decision of the Primary Examiner is reversed, the motion may be brought again when the interference is reinstated or redeclared; if reinstated, a new motion brought and granted would presumably be followed by another ex parte appeal and another reversal of the decision. There would be no logical conclusion to such proceedings, and to permit them would be absurd. The practice of permitting motions for dissolution to be brought is believed to be good. If appeals upon these motions are to be permitted, the prosecution thereof must be inter partes, to save the whole proceedings *476upon the motion from becoming farcical. The rules at present do provide for appeals, and it is not deemed expedient to change them in this respect at the present time.”
We conclude, therefore, that the provisions relating to ex parte applications do not apply to inter partes actions, and that when the appeal from the decision of the Primary Examiner was abandoned, his decision became final and binding upon the parties.
But it is insisted that mandamus is not the proper remedy. When the decision of the Primary Examiner that Thompson and Lemp had no right to make the claims in issue became final and res judicata, those parties were eliminated from the case, and appellant was entitled to go hence in the full and uninterrupted enjoyment of the patent. Under the statute, the jurisdiction of the Commissioner attaches when he directs the declaration of an interference, and he still retains jurisdiction to award priority to the successful party after his adversary has been eliminated. It would indeed be an anomalous situation, if his determination that one party to an interference has m> right to make the claims in issue, and therefore is not entitled to a judgment of priority, operates to deprive him of jurisdiction to award priority to the other party, who has the right to make «the claims in issue, and who is entitled to an award of priority. The remedy of the defeated party is by way of appeal. He has no right whatever thereafter to prosecute the claims of the issue in an ex parte case. It follows, therefore, that when Thompson and Lemp abandoned their appeals from the decision of the Primary Examiner denying their right to make the claims in issue, that decision became final and res judicata as between the parties to the interference, and that thereafter the Commissioner was without authority to direct the Primary Examiner to readjudicate, in Thompson’s and Lemp’s ex parte applications, the question whether they had the right to make the identical claims of the issue in the interference proceeding. If this remedy is denied it, appellant will be again compelled to litigate with Thompson and Lemp in the Patent Office the same question which we have held has already been finally de*477termined in its favor. All this will involve expense, delay, and loss. The Commissioner, being without authority to direct a readjudication of the question involved in the former interference, has no discretion in the premises, for "whether the former decision was right or wrong, or was induced by the want of the particular evidence that was offered in the present case, is not the question. However that might be, it was final and put an end to the litigation in the first interference.” Blackford v. Wilder, 28 App. D. C. 551.
It is no answer to the petition of appellant, that the Commissioner deemed himself possessed of the authority he exercised, if no discretion in the premises was committed to him and he was in fact acting beyond his authority and without warrant of law. Garfield v. United States, 30 App. D. C. 177; United States ex rel. Daly v. Macfarland, 28 App. D. C. 552.
Seymour v. United States, 10 App. D. C. 567, confidently relied upon by appellee to defeat appellant’s right to the writ, is not in point. That case, like this, involved an interference between an application and unexpired patent, but in that case the decision dissolving the interference had been acquiesced in by the junior party, leaving the senior party in full possession and enjoyment of his patent. This court very naturally held that the patentee was not entitled to a writ of mandamus to compel the Commissioner of Patents to reinstate the interference proceeding, because he had suffered no legal injury whatever, and because he remained “in full possession of all his legal rights to the same extent as before he was summoned to defend those rights.”
In the instant case a second attack, not authorized by law, has been instituted against appellant’s patent, and necessarily has impaired that patent. There being no other adequate and speedy remedy, we think appellant entitled to the relief sought.
The judgment of the court below must be reversed, and the cause remanded to that court, with directions to issue the writ as prayed.
Reversed,.
A writ of error to the Supreme Court of the United States» was allowed March 18, 1908.