Wis. Stat. § 23.81: Effect of plea of no contest.

Forfeiture of deposit under s. 23.75 (3) (b), an accepted plea of no contest under s. 23.70, or a stipulation of no contest under s. 23.75 (3) (c) to a charge of violation of a natural resources law shall not be admissible in evidence as an admission against interest in any action or proceeding arising out of the same occurrence.