A blue light illuminating the rear license plate is an apparent equipment violation and thus justified the stop of Hansen’s car. Once stopped, the officer had reasonable suspicion to extend the stop to investigate whether Hansen was operating while intoxicated.
Section 347.13(3) requires vehicles operating on Wisconsin highways to have a white light illuminating the rear license plate, but Hansen argues there are exceptions to this apparently categorical rule, citing § 347.25(4), which allows police vehicles to display blue lights, so the officer should have ruled out the possibility that Hansen’s car was an unmarked police vehicle before stopping him.
Apart from the general rule that an officer doesn’t have to rule out a possible innocent explanation before making a stop, specific provisions regarding the use of blue lights on police vehicles prescribe flashing, oscillating, or rotating lights mounted on the passenger side of the vehicle, e.g., § 347.25(1m)(a) and (b), and Hansen’s plate light was obviously not of that kind. Thus, there were no pertinent statutory exceptions for the officer to rule out before stopping Hansen. On top of that, the court lists other common-sense reasons why its not reasonable to think an unmarked police car would have a blue plate light. Thus, the stop was reasonable. (¶¶15-28).
Having reasonably stopped Hansen, the officer reasonably extended the stop because the officer’s initial interaction with Hansen established reasonable grounds to suspect Hansen was operating while intoxicated. The court rejects Hansen’s arguments that the circuit court made clearly erroneous factual findings regarding the officer’s observations and that the absence of “bad driving” precluded reasonable suspicion. (¶¶29-37).