Law enforcement officers in Wisconsin patrol the roads in an effort to reduce the number of drunk or impaired drivers putting others at risk. Unfortunately, sometimes people who aren’t actually operating a vehicle while impaired (OWI) can wind up charged with a crime because of mistakes made by officers during a traffic stop.

Defending against OWI charges is possible. The better you understand how the state builds a case related to impaired driving charges, the better informed you will be when it comes time to make decisions about your defense strategy.

Much of the case relies on the officer’s report

Typically speaking, the officer will need to have a reason to pull you over unless the stop was part of a sobriety checkpoint or roadblock. Beyond that, they will also make a note of what they witnessed while you were in your own vehicle that led them to ask you to exit the vehicle for a roadside sobriety check.

The field sobriety test administered by law enforcement may check you for multiple different symptoms of impairment, from involuntary movement in your eyes, to difficulty with balance or cognition. The officer must carefully note the results of that test as well.

Chemical tests often helped build impaired driving cases

If you fail a field sobriety test, the law enforcement officer involved in the traffic stop will most likely then ask you to perform a chemical breath test by blowing into a Breathalyzer unit. If the results show that your blood alcohol content (BAC) is 0.08% or higher, the officer will likely arrest you. Even if the test shows lower results, the officer may still arrest you under suspicion of the use of a different intoxicant than alcohol.

Common defense strategies could include undermining the validity of the test itself, showing that the breath unit had received inadequate calibration or demonstrating an alternative explanation for the results that indicated impairment.