The defendant in error, petitioner below, on June 9, 1920, filed a petition in the Supreme Court of the District of Columbia, praying for a writ of mandamus against respondents requiring them to issue to her a permit to erect a building for business purposes on a lot situated on a residence street in Washington. Prior to filing the petition she made preparations to erect the building and applied to the building inspector for a permit, which he declined to issue, upon grounds not necessary to be stated here.

The plaintiffs in error, respondents below, filed an answer to the petition and return to the rule to show cause, and to the answer a demurrer was interposed. On July 6, 1920, the demurrer was overruled, the rule to show cause discharged, and petition dismissed. Upon appeal to the Court of Appeals this judgment was, on February 7, 1921, reversed and the cause remanded, with directions to issue the writ as prayed. Schwartz v. Brownlow, 50 App. D. C. 279, 270 Fed. 1019. On March 19, 1921, an application for a rehearing was overruled, and on June 13th following, this writ of error was allowed.

On March 14th, after the decision of the Court of Appeals, but before the allowance of the writ of error, the permit demanded by petitioner was issued by the building inspector, and thereupon the building was constructed. It had been fully completed when the writ of error was allowed. On June 2, 1921, petitioner conveyed all her interest in the property to persons not parties to this cause.

It thus appears that there is now no actual controversy between the parties—no issue on the merits which this court can properly decide. The case has become moot for two reasons: (1) Because the permit, the issuance of which constituted the sole relief sought by petitioner, has been issued and the building to which it related has been completed; and (2) because, the first reason aside, petitioner no longer has an interest in the building, and therefore has no basis for maintaining the action.

This court will not proceed to a determination when its judgment would be wholly ineffectual for want of a subject matter on which it could operate. An affirmance would ostensibly require something to be done which had already taken place. A reversal would ostensibly avoid an event which had already passed beyond recall. One would be as ain as the other. To adjudicate a cause which no longer exists is a proceeding which this court uniformly has declined to entertain. See Mills v. Green, 159 U. S. 651, 16 Sup. Ct. 132, 40 L. Ed. 293; Codlin v. Kohlhausen, 181 U. S. 151, 21 Sup. Ct. 584, 45 L. Ed. 793; Little v. Bowers, 134 U. S. 547, 556, 10 Sup. Ct. 620, 33 L. Ed. 1016; Singer Manufacturing Co. v. Wright, 141 U. S. 696, 699, 12 Sup. Ct. 103, 35 L. Ed. 906; American Book Co. v. Kansas, 193 U. S. 49, 24 Sup. Ct. 394, 48 L. Ed. 613; United States v. Hamburg-American Co., 239 U. S. 466, 475, 36 Sup. Ct. 212, 60 L. Ed. 387; Berry v. Davis, 242 U. S. 468, 470, 37 Sup. Ct. 208, 61 L. Ed. 441; Board of Public Utility Com'rs v. Compania General de Tabacos de Filipinas, 249 U. S. 425, 39 Sup. Ct. 332, 63 L. Ed. 687; Commercial Cable Co. v. Burleson, 250 U. S. 360, 39 Sup. Ct. 512, 63 L. Ed. 1030; Heitmuller v. Stokes, 256 U. S. 359, 41 Sup. Ct. 522, 65 L. Ed. 990.

It is urged that the permit was issued by the inspector of buildings only because he believed it was incumbent upon him to comply with the judgment of the Court of Appeals and avoid even the appearance of disobeying it. The motive of the officer, so far as this question is concerned, is quite immaterial. We are interested only in the indisputable fact that his action, however induced, has left nothing to litigate. American Book Co. v. Kansas, supra. The case being moot, further proceedings upon the merits can neither be had here nor in the court of first instance. To dismiss the writ of error would leave the judgment of the Court of Appeals requiring the issuance of the mandamus in force—at least apparently so—notwithstanding the basis therefor has disappeared. Our action must, therefore dispose of the case, not merely of the appellate proceeding which brought it here. The practice now established by this court, under similar conditions and circumstances, is to reverse the judgment below and remand the case with directions to dismiss the bill, complaint, or petition. United States v. Hamburg-American Co., supra; Barry v. Davis, supra; Board of Public Utility Com'rs v. Compania General de Tabacos de Filipinas, supra; Commercial Cable Co. v. Burleson, supra; Heitmuller v. Stokes, supra.

Following these precedents, the judgment below should be reversed, with directions to the Court of Appeals to remand the cause to the Supreme Court, with instructions to dismiss the petition, without costs, because the controversy involved has become moot, and therefore is no longer a subject appropriate for judicial action.

And it is so ordered.