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Reasons a breath alcohol test could give an incorrect reading

On Behalf of | Mar 1, 2024 | Criminal Defense

Getting stopped by the police is often unnerving. If the officer suspects you of driving under the influence, the situation can become even more unsettling because of the potential consequences.

To check whether you are over the legal limit, the officer may use a breath alcohol test. However, these devices are not infallible, and you might be able to challenge the results at trial for any of the following reasons.

Improper calibration by the officer

Officers must follow strict rules in Wisconsin regarding the maintenance and calibration of breath tests because improper calibration of a device will alter the results. To prove an officer did not calibrate a breath alcohol test correctly, you can request records. These records should show when the department calibrated the device and how they did so. Any gaps in the records could indicate problems.

Additionally, you can ask for maintenance logs to see if they regularly cared for the device. If these logs are missing or incomplete, it suggests the device might not have been working accurately. Providing evidence of irregularities in the process can cast doubt on the accuracy of the results.

Electronic interference from nearby devices

Electronic interference can occur when other devices are in the area. The signals from these devices can confuse the testing device and lead to an inaccurate reading.

Such interference can come from things like cell phones, radios or even nearby power lines. If you can supply evidence that you had to take the test in a spot where a lot of electronic activity was present, you might have a basis for tossing out the results.

Medicines and medical conditions

Some medicines or medical conditions can produce substances in your body that the test might confuse with alcohol. For example, diabetes or being on a low-carb diet can produce chemicals in your breath that resemble alcohol. Similarly, using mouthwash or certain medications can also affect the test. Credible evidence of these factors can also call breath test results into question.

Granted, breath tests are relatively accurate. Still, you should be aware of reasons you can challenge their results when facing harsh DUI penalties.