Wis. Stat. § 971.06: Pleas.

(1) A defendant charged with a criminal offense may plead as follows:

(a) Guilty.

(b) Not guilty.

(c) No contest, subject to the approval of the court.

(d) Not guilty by reason of mental disease or defect. This plea may be joined with a plea of not guilty. If it is not so joined, this plea admits that but for lack of mental capacity the defendant committed all the essential elements of the offense charged in the indictment, information or complaint.

(2) If a defendant stands mute or refuses to plead, the court shall direct the entry of a plea of not guilty on the defendant’s behalf.

(3) At the time a defendant enters a plea, the court may not require the defendant to disclose his or her citizenship status.