Wis. Stat. § 782.19

The prisoner may move to strike the return or may deny any of the material facts set forth in the return to the writ or allege any fact to show either that the imprisonment is unlawful or that the prisoner is entitled to a discharge, which allegations and denials shall be verified by oath; and the court or judge shall proceed in a summary way to examine into the facts contained in the return and to hear the allegations and proofs of the parties in support of such imprisonment or against the same.