The Iowa Supreme Court has upheld a lower court ruling that threw out evidence in an Estherville woman’s drunk driving conviction. A Estherville police officer saw a car making a u-turn on Central Avenue just before one A.M. on May 25th of 2008.

The officer pulled over the car as Estherville has an ordinance that prohibits u-turns on that street. The officer suspected the driver of the car, Donna Louwrens, was drunk and she did fail an alcohol breath test. Louwrens asked that the breath test be thrown out as she said the officer had no probable cause to stop her car.

Her defense stated that state law requires cities to post signs indicating that u-turns are prohibited before the ordinance can take effect and there were no such signs in Estherville. The district court ruled it was a mistake of law and could not provide probable cause for the traffic stop and agreed to Louwrens’ motion to suppress the breath test.

The Iowa Supreme Court ruling said the court record provided no testimony from the officer to show the issue was anything but a mistake of law and said such a mistake could not be used as probable cause for the traffic stop.