OWI Breath Tests

Often, two breath tests are used during an OWI arrest: a roadside test and the evidentiary breath test. While not as accurate, the roadside breath test is administered during the OWI traffic stop to determine if there is enough evidence to make a drunk-driving arrest. This test is entirely voluntary. The evidentiary breath test is administered at the police station. Because these results are more accurate, they may be used to prove that the driver was under the influence. Refusing to take this test is a violation of the Implied Consent law, and could result in an administrative license suspension.

The breath test machine used by Wisconsin law enforcement is the Intoximeter EC/IR II. This machine works by analyzing the amount of alcohol in an individual’s breath to calculate BAC. However, this test has a number of known problems that could affect its ability to deliver accurate results. For example, this particular machine is known to be affected by radio frequency interference—which means that your reading could be skewed by cell phones or even police radios.

To ensure that the Intoximeter EC/IR II is in good working order, police departments are required to keep up with their calibration and maintenance. Your defense attorney can request the department’s logbooks to determine if the machine was calibrated and maintained on a routine basis. If not, your breath test reading may be challenged.