Police officers who pull someone over for suspected drunk driving typically begin gathering evidence right away. They ask motorists if they have had anything to drink. They take notes about their conduct, record their driving before the traffic stop and may engage in enhanced screening.
After a field sobriety test, police officers may decide to arrest someone for a driving while intoxicated (DWI) offense. At that point, the officer may require that the driver perform a chemical breath test. If the driver fails the breath test, that may only contribute to the evidence against them. However, any of the three factors below may have contributed to inaccurate test results.
Medical challenges
There are a variety of health issues that can reduce the accuracy of chemical breath testing. Perhaps the most common involves uncontrolled blood sugar issues. Someone with unmanaged or undiagnosed diabetes could have acetone on their breath, and that could trigger a false positive on a chemical breath test. There are other medical issues that could also affect the accuracy of test results. Even certain prescription medications, including asthma inhalers, could cause false positives during chemical breath testing.
Hygiene or dietary habits
Some people follow specialized diets that could reduce the accuracy of breath tests. Many others have hygiene habits that could include using mouthwashes or breath sprays that have alcohol in them. Especially if someone uses mouthwash or breath spray immediately before a traffic stop, the presence of those compounds in their mouth could trigger a false positive on a breath test that makes it look as though they have had too much to drink.
Calibration or maintenance issues
Finally, a false positive could occur because of an issue with the breath test unit and not the person taking the test. Police departments need to regularly maintain the devices, which might involve physically working on the devices or installing software updates as necessary. They also need to frequently calibrate testing devices to ensure that they can produce accurate results. The failure to properly maintain and calibrate breath test units can lead to inaccurate readings and evidence that may not be as accurate as people assume.
Identifying the source of inaccurate breath test results can provide the basis for someone’s criminal defense strategy after they’ve been accused of impaired driving. Seeking legal guidance is a good way to get started.
