Challenging DUI stops on a lack of probable cause: Part I

Challenging DUI stops on a lack of probable cause: Part I

For a drunk driving charge to be legitimate, police need to prove that they followed proper procedure. For instance, defense attorneys may try to challenge how a field sobriety test was administered. And at the heart of any DUI conviction is this question: did the officer have probable cause to pull over the suspect?

In Wisconsin, as in other states, police officers need to prove that the suspect was driving in such a way that the officer had a reason to pull him over. If the officer can’t prove probable cause, a DUI conviction can be overturned. In our posts this week, we’ll talk about two recent examples from here in the Midwest.

Earlier this month, the Iowa Court of Appeals overturned one man’s DUI conviction because the officer’s testimony did not match video taken from his squad car’s “Dashcam,” which is the camera mounted on the dashboard.

In November of 2009, the 49-year-old man was pulled over by a police officer and arrested for DUI. In his incident report, the officer said: “I observed this vehicle going from fog line to center line multiple times. At times, it appeared that the vehicle was going to go into the ditch.”

In short, he claimed that the car had been noticeably swerving. At the original trial, a judge reviewed the tape and found the defendant guilty. However, the three appellate judges who looked at the same tape found that it did not match the officer’s testimony.

They said that there were instances in which the driver weaved slowly and gently, but none of his driving seemed erratic enough to justify the officer’s traffic stop. Therefore, the evidence against the driver was suppressed and the conviction was overturned.

One of the judges wrote: “We recognize that in certain circumstances a videotape can speak for itself, but in this instance, we find the videotape speaks fairly softly.”

Check back later this week as we discuss another recent example involving a DUI stop without probable cause.

Source:, “Iowa: Dashcam Video Undermines Police Testimony,” Sept. 13, 2011