The Wisconsin Court of Appeals routinely sees claims from drivers that evidence of their intoxication should have been suppressed because the initial traffic stop was invalid. Most of the time, it's pretty obvious why an officer got suspicious.
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According to the opinion, Fred A. Ederer was driving north on U.S. 51 in Leeds about 1 a.m. in October 2009. Sheriff's Dep. Chad Steinle began to follow him. Steinle ran Ederer's plate and saw it was registered in neighboring Sauk County.
Ederer pulled into a driveway and stopped. Steinle parked across the street and waited. Ederer resumed driving north on U.S. 51 and Steinle resumed following him. Where the highway veered west, Ederer continued straight onto Hwy 22. When Ederer pulled into a tavern parking lot, Steinle activaed his emergency lights and stopped Ederer -- purportedly for not using his turn signal when he left U.S. 51 for Hwy 22.
Ederer argued that because he basically went straight he didn't need to use a turn signal. The trial court disagreed, stating, “When he exited Highway 51 and went to
22, whether it’s straight or not, it is still a turn on a highway which may affect other traffic.”
http://www.jsonline.com/blogs/news/121707719.html