Wis. Stat. § 939.43
The prosecution of an individual who relied on a governmental official's statutorily required legal opinion would impose an unconscionable rigidity in the law. State v. Davis, 63 Wis. 2d 75, 216 N.W.2d 31 (1974). Mistake is not a defense to criminal negligence. A defendant's subjective state of mind is not relevant to determining criminal negligence. State v. Lindvig, 205 Wis. 2d 100, 555 N.W.2d 197 (Ct. App. 1996), 96-0235.