Wis. Stat. § 972.02: Jury trial; waiver.

(1) Except as otherwise provided in this chapter, criminal cases shall be tried by a jury selected as prescribed in s. 805.08, unless the defendant waives a jury in writing or by statement in open court or under s. 967.08 (2), on the record, with the approval of the court and the consent of the state.

(2) At any time before the verdict, the parties may stipulate in writing or by statement in open court, on the record, with the approval of the court, that the jury shall consist of any number less than 12.

(3) In a case tried without a jury the court shall make a general finding and may in addition find the facts specially.

(4) No member of the grand jury which found the indictment shall be a juror for the trial of the indictment.