DUI Arrests: PAS Tests

Preliminary Alcohol Screening devices, commonly referred to as PAS tests, are devices police officers use to determine probable cause to make a DUI arrest. A person stopped for a DUI is not obligated to take the PAS test: It is a voluntary test and is not subject to the "implied consent" laws.

The most widely used PAS device in California is the Alco-Sensor III or IV. The Alco-Sensor utilizes fuel cell technology to detect the presence of alcohol in a breath sample. This handheld device is relatively small. It has a mouthpiece to blow into and a sample chamber to hold the air. It determines alcohol concentration by measuring the electrical reaction caused by alcohol oxidation.

Unfortunately, PAS devices react to rubbing alcohol, wood alcohol and acetone. This skews the test results for some diabetics, people who are fasting and people whose professions expose them to certain chemicals.

Another major problem with PAS tests is that they do not have mouth alcohol detectors to determine if mouth alcohol is present. Mouth alcohol is the undetected, raw, unabsorbed alcohol in the mouth that falsely elevates the results of the breath test. The sources of mouth alcohol may include a substance ingested prior to the breath test, a substance regurgitated or burped from the stomach, dental work or a case of gastroesophogeal reflux, also known as GERD.

There is no time period that the officer must wait before administering the PAS test. Science has proven that alcohol evaporates from the mouth in 15 minutes, so if a person refrains from eating anything or regurgitating any fluids for 15 minutes, there will be no residual alcohol in the mouth. However, PAS tests do not have this time requirement. Thus, with no time requirement and no slope detector, BAC readings from PAS tests often report an inaccurate BAC reading, which results in the police officer making an arrest for DUI.

PAS devices must be properly calibrated and maintained to assure the accuracy of its readings. Police agencies must keep detailed records of the maintenance schedule. PAS devices often have to be checked every 150 tests, or 10 calendar days. Therefore, a lawyer should get the past records of the PAS device to check for any issues with the device and to check for a pattern of suspicious test results.

If you or a loved one was arrested for DUI, please contact a skilled defense attorney immediately.