Utah Code § 78B-6-809: Proof required of plaintiff -- Defense.

(1) On the trial of any proceeding for any forcible entry or forcible detainer the plaintiff shall only be required to show, in addition to the forcible entry or forcible detainer complained of, that the plaintiff was in actual peaceable possession at the time of the forcible entry, or was entitled to the possession at the time of the forcible detainer.

(2) In defense, the defendant may show that the defendant or the defendant's ancestors, or those whose interest in the premises is claimed, had been in the quiet possession of the property for the space of one entire year continuously before the commencement of the proceedings, and that his interest is not ended or determined, and that this showing is a bar to the proceedings.

(3) An action for unlawful detainer may also be brought in the form of a counterclaim .