Wisconsin Statutes Vehicles (Ch. 340 to 351) § 349.02. Police and traffic officers to enforce law

(2)(a) Notwithstanding sub. (1), a police officer, sheriff, deputy sheriff, traffic officer or motor vehicle inspector may not stop or inspect a vehicle solely to determine compliance with a statute or ordinance specified under par. (b) unless the police officer, sheriff, deputy sheriff, traffic officer or motor vehicle inspector has reasonable cause to believe that a violation of a statute or ordinance specified under par. (b) has been committed. This paragraph does not limit the authority of a police officer, sheriff, deputy sheriff, traffic officer or motor vehicle inspector to make an arrest or issue a citation for a violation of any statute or ordinance specified under par. (b) observed in the course of a stop or inspection made for a lawful purpose. This paragraph does not apply to a traffic officer or motor vehicle inspector in the performance of duties under s. 110.075(2).

(b) The statutes and ordinances covered under par. (a) are all of the following:

(c) Notwithstanding par. (a), a law enforcement officer may not stop a vehicle solely because the vehicle's color differs from the color stated in the application for registration of that vehicle. This paragraph does not limit the authority of a law enforcement officer to issue a citation for improper registration of a vehicle whose color differs from the color stated in the application for registration of the vehicle, if the difference is observed in the course of a stop or inspection made for other purposes.

(3)(a) In this subsection, “photo radar speed detection” means the detection of a vehicle's speed by use of a radar device combined with photographic identification of the vehicle.

(b) Notwithstanding sub. (1), the state and local authorities may not use photo radar speed detection to determine compliance with any speed restriction imposed by s. 346.57, 346.58, 346.59, 346.595 or 349.11 or a local ordinance in conformity therewith.