Wisconsin OWI – How is Blood Alcohol Level Determined?

Your BAC is determined by testing your blood, breath or urine. Blood and urine testing are accomplished by taking a sample and sending it to the state crime lab. Breath testing is done at the police station by blowing into the Intoximeter or related machine.

Breath testing is most common, because police don’t have to send in a sample to get results. These machines can only detect alcohol, though, so another method is needed if use of drugs is suspected.
Blood testing may only be done according to approved methods established by the Wisconsin Hygiene Lab. Blood may only be drawn by qualified medical personnel.
Urine testing is used less often. It is the least accurate of the three, and has all the same requirements of blood testing: a licensed person has to perform the testing according to Department of Hygiene standards.

Police also use a device called a portable breath test, or PBT. About the size of a kazoo, this disposable device can be used at the scene of the stop. For the most part, results of the PBT are not admissible at trial.

Check these topics for more information:

How are the Results of my Breath or Blood Test Used at Court?
What happens to my license if I have a prohibited alcohol concentration?

How are the Results of my Breath or Blood Test Used at Court?

The law says that the results of a breath or blood test are presumed to be accurate and are admissible at trial against you. This applies to any test method authorized by statute. A defense attorney may still challenge the test at trial, but such challenge goes to the “weight and credibility” of the result, not its admissibility. In other words, the jury is going to hear the result. All you can do is try to convince them it is inaccurate. You cannot get the judge to prevent them from hearing it in the first place.

There are exceptions. If there are independent reasons for keeping the results away from the jury, the judge can do that. So, if the sample was taken more than three hours after driving, the court could find the results irrelevant. Or if the evidence is insufficient to connect you to the sample offered, the court could find it lacked authentication. A lawyer can find other challenges as well.

What happens to my license if I have a prohibited alcohol concentration?

If any test, including one taken at your request, shows a prohibited alcohol concentration, the officer will take your license and issue you a notice of administrative suspension. That notice is your driver’s license for the next 30 days (if you had a valid license), after which your license is automatically suspended for six months.

Within ten days of receiving the notice, you may request in writing that DOT review the administrative suspension. That hearing will determine a limited number of issues, specifically:

1. Were you identified correctly?
2. Were you informed of your options under the implied consent law?
3. Did you have a prohibited alcohol concentration at the time of driving?
4. Were the alcohol tests administered according to law?
5. Did any test show a prohibited alcohol concentration?
6. Was there probable cause for arrest?
7. Were you driving a commercial motor vehicle at the time of arrest?

Hearings are casual. They can be done over the phone. The officer does not have to appear unless subpoenaed. He can just submit his report instead. You can submit your position in writing instead of appearing too.

If the hearing officer determines that the requirements for administrative suspension are met and you had a prohibited alcohol concentration at the time of driving, the six month suspension is upheld. If not, you get your license back with no additional fees. All this must happen, and the results mailed to you, within 30 days of the arrest. You can appeal an unfavorable determination to the court where your offense is being tried.

Any time spent on administrative suspension would count toward the total revocation received if ultimately convicted of the offense.