Wis. Stat. § 895.049
Notwithstanding s. 895.045 , failure by a person who operates or is a passenger on a utility terrain vehicle, as defined in s. 23.33(1) (ng) , a motorcycle, as defined in s. 340.01(32) , an all-terrain vehicle, as defined in s. 340.01(2g) , or a snowmobile, as defined in s. 340.01(58a) , on or off a highway, to use protective headgear shall not reduce recovery for injuries or damages by the person or the person's legal representative in any civil action. This section does not apply to any person required to wear protective headgear under s. 23.33(3g) , 23.335(8) (a) or (b) , or 347.485(1) .
Wis. Stat. § 895.049
When this section applies to prohibit a reduction of damages, it necessarily also precludes a person's failure to wear a helmet from being considered a form of negligence. Hardy v. Hoefferle, 2007 WI App 264, 306 Wis. 2d 513, 743 N.W.2d 843, 06-2861.