Wis. Stat. § 32.10

If any property has been occupied by a person possessing the power of condemnation and if the person has not exercised the power, the owner, to institute condemnation proceedings, shall present a verified petition to the circuit judge of the county wherein the land is situated asking that such proceedings be commenced. The petition shall describe the land, state the person against which the condemnation proceedings are instituted and the use to which it has been put or is designed to have been put by the person against which the proceedings are instituted. A copy of the petition shall be served upon the person who has occupied petitioner’s land, or interest in land. The petition shall be filed in the office of the clerk of the circuit court and thereupon the matter shall be deemed an action at law and at issue, with petitioner as plaintiff and the occupying person as defendant. The court shall make a finding of whether the defendant is occupying property of the plaintiff without having the right to do so. If the court determines that the defendant is occupying such property of the plaintiff without having the right to do so, it EMINENT DOMAIN 32.1217 shall treat the matter in accordance with the provisions of this subchapter assuming the plaintiff has received from the defendant a jurisdictional offer and has failed to accept the same and assuming the plaintiff is not questioning the right of the defendant to condemn the property so occupied.