Wis. Stat. 323.20
Liability: Emergency Use of Vehicles Allowed
When an emergency declaration is in effect and following a request for aid, an individual who operates any boat or motor vehicle in the state, even if the vehicle is not registered in Wisconsin, will not be held legally responsible.
Emergency Use of Vehicles
In responding to an official request for help during any declared state of emergency, any person may operate a boat or any motor vehicle, including a snowmobile, all-terrain vehicle, or utility terrain vehicle, that is not registered in this state.