It is a fundamental principle at the foundation of our judiciary system that courts sit only to decide actual controversies, and not to answer moot questions of law or fact, nor to declare abstract principles or rules of law not applicable to issues or controversies actually before them. 2 Ency. of Pl. & Pr. 342 et seq.; Little v. Bowers, 134 U. S. 547; Washington Market Co. v. District of Columbia, 137 U. S. 62; Singer Mfg. Co. v. Wright, 141 U. S. 696; California v. S. P. & T. R. Co. 149 U. S. 308; Mills v. Green, 159 U. S. 651; Plainfield v. Plainfield, 67 Wis. 525. No less thoroughly established is it that the appellate jurisdiction of this court cannot be successfully invoked unless rights of the appellant are substantially prejudiced by the act appealed from. Benson v. Waukesha, 74 Wis. 31; White v. Sherry, 37 Wis. 225; McGregor v. Pearson, 51 Wis. 122.
Further, it has often been held in Wisconsin that an error *108in the court below will receive no attention on appeal where-it has been corrected by the voluntary act of the favored party before the appeal was perfected. Duffy v. Hickey, 68 Wis. 380; Reinig v. Hartman, 69 Wis. 28; Littlejohn v. Turner, 73 Wis. 113; German M. F. F. Ins. Co. v. Decker, 74 Wis. 556.
The question of practice whether, if the entire error upon which the appeal is based has.been corrected, the appeal should be dismissed, or the act of the court below be affirmed, seems not to have been expressly passed on in Wisconsin, for the reason probably that in all cases where such a correction has been presented other issues were also brought up by the appeal. The practice of dismissal, where the entire controversy has been disposed of by the elimination of the error below, is, however, approved repeatedly by the supreme court of the United States, and was the practice followed in all of the cases cited from that court. We see no reason why. that practice should not be pursued. A party whose entire ground of complaint has been removed by action of either the adverse party or the court below has: no justification for appealing to this court, and, if he does so,, should be at once dismissed, upon the fact being made fully to appear. That is shown here. The consent of the plaintiff on file in the circuit court for La Crosse county would have accorded to the defendant all the relief which could result from the filing of a remittitur from this court reversing the judgment below and ordering dismissal of the complaint, and, upon the dismissal of this appeal,, that relief is still at its disposal.
By the Court.— Appeal dismissed.