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Preliminary Alcohol Screening Device

Young driver arguing with a police officer about breathylzer

A PAS Test – preliminary alcohol screening test- is a roadside breath test that the police may use to determine whether a driver is under the influence of alcohol.   Many law enforcement agencies are equipped with them and have dedicated officers who are trained to calibrate and ensure the accuracy of the machines.  An officer will administer the PAS test prior to the driver being placed under arrest for DUI.

Can I Refuse a PAS?

In most circumstances you may refuse a PAS test unless you fall into two categories.  If you are under the age of 21 or you are on probation for a previous DUI, you cannot refuse a PAS. If you do, you will face tougher penalties which will include a loss of your driver’s license, enhanced DUI penalties, and if on probation, your probation may be revoked and you could be sentenced to serve time in custody.

However, if you do not fall into these categories, you may refuse a PAS test without consequence.  The PAS test is just like any other field sobriety test which may be refused and are designed to aid the police in deciding whether probable cause exist to arrest the driver for DUI.

If you chose not to take the test, you should remain polite but firm in declining to take the test.  Do not argue with the police nor allow them to persuade you with tactics such as telling you that if you take the test they will let you go home, or that the test will rule you out as a DUI suspect.  The fact is that in order to administer the test the police must have already developed probable cause for an arrest to administer it.  The courts have made this ruling to prevent law enforcement from simply administering the test without further investigation.  So if you’ve been offered a PAS then they already have enough probable cause to arrest.

How a PAS Machine Works

A PAS device functions using fuel cell technology.   This is similar to the evidentiary breath test machine that is used by local police and CHP to determine the concentration of alcohol in a person’s blood stream.  In essence, the breath sample reacts with an electrolyte in the fuel cell to produce an electrical current. The amount of electrical current generated is then converted using a mathematical formula that produces a three-digit number which correlates to the amount of alcohol in the person’s blood.

PAS Procedure

A PAS will be administered only after the police have conduct a DUI investigation which will include identification of objective signs of intoxication and field sobriety tests.  Prior to administering the test, an officer will provide you with what is known as a “PAS Admonishment”.  The PAS Admonishment reads:

“I am requesting that you take a preliminary alcohol screening test to further assist me in determining whether  you are under the influence of alcohol. You may refuse to take this test; however, this is not an implied consent test and if arrested, you will be required to give a sample of your blood, breath or urine for the purpose of determining the actual alcoholic and drug content of your blood.”

Prior to administering the PAS the officer will conduct a fifteen minute observation period.  In that period, the officer is looking to see if you have consumed any food or drink, burped, vomited or ingested anything.  During the fifteen minutes the PAS device will be turned on and will conduct a cycle and zero itself out, ensuring that there is no ethanol in the machine.  The officer will remove a sealed mouthpiece from a kit and place it in the machine.  The officer will then instruct you to blow until the officer tells you to stop. The machine will provide a three-digit number based upon the results.

In a properly conducted PAS test, the officer will then insert a new second mouthpiece into the machine and repeat the process. The officer is supposed to wait at least three minutes between each test.  After the conclusion of the second test, depending upon the results, the officer may request you take a third test.

How Will the PAS Test Be Used In Court?

When the prosecution is trying to establish the elements of either the “A” count or the “B” count, they may try to use the PAS test results to show what your BAC was at the time of driving.  The prosecution will try to show that the PAS device was properly checked for accuracy, that two samples were taken that are within .02 of each other, and that the officer properly administered the test.

Since the PAS test is usually administered within 15 minutes of a traffic stop, the results can be damning to a jury, especially against the “rising blood alcohol” defense.   It can be very effective for a prosecutor to argue that there is a blood sample at or near the time of driving and that a second sample, which often is similar or near the PAS test result, to show your BAC. 

DUI Probation

If you are on probation for a DUI, you cannot refuse to take PAS test.  If you do, you will face additional punishments.  If you are on DUI probation, you may not drive with any alcohol in your system.  If you are on probation and you refuse to take a PAS, your driver’s license will face an automatic suspension for minimum of one year.  You will also face additional consequences by the courts. Even if you are not arrested for a DUI, the police and prosecutor can request that the court sustain a violation of probation and you could serve custody time.

How to Challenge a PAS

Challenging a PAS device comes down to attacking the reliability of the machine, or the manner in which it was administered.  Machine wise, a DUI defense attorney can analyze the results of prior testing on the machine to ensure that it complied with the standards required under California’s Title 17 law.  This includes whether the machine is properly calibrated and maintained.  The defense can also challenge the validity of the way in which the test was administered. There are numerous ways that a PAS result can be skewered.  For example, if an officer fails to properly change the mouthpiece between tests, if a full sample is not recorded, or if the machine has a history of false readouts.

Dedicated DUI Attorney

Kevin Ballard is a dedicated DUI attorney based in Fairfield who understands how to effectively defend those charged with DUIs. Kevin is one of the few attorneys who is both a former prosecutor and trained as a police officer. As such, Kevin knows first hand how DUIs are handled from the initial traffic stop through prosecution and appeal. Let the Law Office of Kevin L. Ballard help you today defend your rights and protect your liberty.