Earlier this month, the Wisconsin Supreme Court held that a sheriff's deputy knocking on a car window, by itself, was not a sufficient show of authority to lead the driver to believe that he was being detained. As a result, the encounter was consensual because the driver could have driven away at any time.
At around 1 a.m. on Christmas Day 2011, Grant County Sheriff's Deputy Matthew Small noticed a car pull into a closed park and stop in the parking lot. Small pulled up behind the car, but didn't have his red-and-blue lights on. He walked up to the window and tapped on it, telling him to roll down the window. Daniel Vogt rolled down the window. Small administered a field sobriety test, which Vogt failed. Vogt was arrested for driving while intoxicated and later moved to suppress evidence obtained from the traffic stop.