A police officer who stops a driver for the suspicion of drunk driving has various tools that they can use to determine if the driver is actually impaired. One of these is the preliminary alcohol screening (PAS) device, which is a handheld breath test device.
The PAS device can give officers an estimate of the blood alcohol concentration (BAC) for a driver, but the result isn’t admissible in court. Calibration challenges that come from being moved around and being in a vehicle mean that it’s not reliable enough to be used as evidence. Instead, its purpose is to let the officer know if there is reason to pursue more reliable methods of determining the BAC.
Other factors that affect results
PAS devices use an electrochemical process to measure alcohol in the breath, but the result might not be accurate if the driver vomited, burped, smoked, or ate before the test. In some cases, those activities can lead to a higher result than what’s valid. It’s also possible that other chemical compounds on the breath might be read as alcohol, which can also skew the test.
If a driver has a high PAS result, the officer may ask them to take a field sobriety test or take them in for a more reliable and accurate test to measure their BAC. Chemical tests, including blood tests, urinalysis and breath tests on a larger stationary machine, are all considered reliable enough to be used in court.
Being arrested for drunk driving requires the defendant to start considering defense strategies. Working with someone familiar with these matters may be beneficial for them so they can review their options and craft a comprehensive plan.