I am Joel Brand, and I defend DUI cases across California. In this post I explain the preliminary alcohol screening test, also called the PAS device, that officers use at the roadside during a traffic stop. Many people are confused about whether this test is mandatory. I want to clear up that confusion and explain what the law actually says.
What Is the PAS Device
The PAS is a small handheld breath testing device that officers carry in their patrol cars. The officer asks you to blow into a mouthpiece, and the machine gives a number that is supposed to represent your blood alcohol concentration. Officers use this device during the investigation phase, before they decide whether to arrest you. It is important to understand that this device is not the same as the larger stationary breath machine at the station. The PAS is a screening tool, not the evidentiary test that happens after an arrest.
The PAS Is a Field Sobriety Test
Under California law, the PAS is classified as a field sobriety test. That means it sits in the same category as the walk and turn, the one leg stand, or the finger to nose test. Field sobriety tests are optional for adults. The officer uses them to gather evidence to help decide if there is probable cause to arrest you. Because the PAS is just another field sobriety test, the same voluntary rule generally applies to it.
Most Adults Can Decline the PAS
If you are 21 or older and you are not on DUI probation, you generally have the right to decline the PAS test. Many of my clients tell me they blew into the device because they thought they had no choice. The officer may have told them to blow, and they assumed that meant it was required. In reality, for most adults, the PAS is voluntary. This is one of the most common misunderstandings I see in DUI cases.
When the PAS Is Mandatory
There are important exceptions. If you are under 21, you must submit to the PAS test under California law. The same is true if you are on DUI probation. For these groups, the PAS is not optional. Refusing the test in these situations carries its own consequences. But for a typical adult driver who is 21 or older and not on probation, the general rule is that the test is voluntary.
The Difference Between PAS and the Evidentiary Test
This is where a lot of confusion happens. The PAS test happens before arrest, at the side of the road. The evidentiary test happens after arrest. Once you are arrested, California implied consent law requires you to submit to a chemical test, which could be breath or blood. That post arrest test is mandatory. Refusing the evidentiary test carries serious license consequences. So remember, the roadside PAS is generally voluntary, but the post arrest chemical test is required.
Why Officers Push the PAS
Officers rely on the PAS because it gives them a number quickly. That number helps them build probable cause for an arrest. Without the PAS result, the officer has to rely on observations like your driving pattern, your performance on the physical field sobriety tests, and the officer's subjective opinion about your speech and balance. The PAS gives the officer something concrete to point to. That is exactly why understanding your right to decline matters so much.
What Happens If You Declined the PAS
If you declined the PAS and you are an adult not on probation, the officer cannot penalize you for that refusal in the same way the law penalizes refusal of the post arrest evidentiary test. The officer may still arrest you based on other observations. But you did not give them a breath number to use against you at the roadside. Whether declining was the right choice depends on the specific facts of your stop, and I look at every detail when I review a case.
What Happens If You Took the PAS
If you blew into the PAS, that result can become evidence in your case. However, the PAS device has limitations. It is a handheld machine used outside, in varying weather conditions, with potential interference from radio frequencies and other sources. The result may not be as reliable as the officer suggests. I examine how the device was used, when it was last calibrated, and whether the officer followed proper procedures. A PAS number alone does not guarantee a conviction.
The Officer Did Not Tell Me It Was Voluntary
This is a complaint I hear often. The law has specific rules about what officers must tell you before asking you to take the PAS. If the officer did not properly advise you of your right to decline, that can become an important issue in your case. I review the officer's body camera footage and audio recordings to see exactly what was said. Every detail matters, and small failures by the officer can affect the outcome of your case.
How the PAS Affects the DMV Hearing
The DMV hearing is separate from the court case, and the PAS result can come up at both. At the DMV hearing, the hearing officer looks at whether the officer had probable cause to arrest and whether you were driving with a blood alcohol level at or above the legal limit. The PAS result may be part of that discussion, but it is not the only factor. You can learn more about how the DMV hearing works and how the PAS fits into that process.
How the PAS Affects Court
In court, the prosecutor may try to use the PAS result as evidence of impairment. But the result is subject to challenge. I look at whether the device was properly maintained, whether the officer was trained to use it, and whether the test was administered correctly. The PAS is a screening tool, not a perfect measurement. I also consider how the PAS fits into the broader picture, including the officer's other observations and any physical field sobriety tests. You can read more about the top DUI defenses to understand how I approach these challenges.
Legal Limits and the PAS
The legal limit for most adult drivers is 0.08. For commercial drivers it is 0.04. For drivers under 21, any measurable alcohol can trigger consequences under the zero tolerance law, which means 0.01. The PAS may show a number at or above these limits, but that number is just a starting point. The legal limit is a threshold, not an automatic conviction. I look at the whole picture, including the reliability of the PAS result and everything else that happened during your stop. You can review the Vehicle Code sections that govern DUI for more background on how these limits work.
Time Sensitive Steps After Your Arrest
If you were arrested for a DUI, you have important deadlines. You generally have 10 days from the date of your arrest to request a DMV hearing to protect your driving privilege. This deadline is strict, and missing it can have serious consequences for your license. I explain this in more detail in the first 10 days after a DUI. You can also learn about how a DUI affects your license and what steps I take to help my clients protect their driving privileges.
Every Case Is Different
I want to be clear that every DUI case depends on its own specific facts. The information in this post is general and is not a guarantee about any particular outcome. The PAS issue is just one piece of a larger puzzle. I also look at the reason for the stop, the field sobriety tests, the arrest process, and the post arrest chemical test. If you want to understand how all these pieces fit together, you can read about the DUI court process step by step and the California DUI FAQ.
If you have questions about your PAS test or any part of your DUI case, I offer a free written case analysis on this page. Call me at (888) 271-6644. I answer my own phone, 24/7. You can also read more from the DUI blog.