How a Roadside PAS Differs From the Breath Test After Arrest
The PAS versus breath test question comes up because many drivers blow into two devices on the same night. The first is a handheld preliminary alcohol screening device used at the roadside. Next comes an evidential breath instrument used after arrest, often at a station or jail. Both read alcohol from breath, yet the law treats them as different tools with different rules.
The difference changes what an officer must say, whether a driver may decline and what a refusal costs at the DMV. It also affects what records exist later and what a lawyer can review.
Sources reviewed in October 2026 include the California Vehicle Code sections on implied consent and screening, Title 17 of the California Code of Regulations and California DMV guidance.
Two Breath Devices With Two Different Jobs
Vehicle Code section 23612(h) describes the preliminary alcohol screening test as a field sobriety test. The officer may use it as a further investigative tool. In other words, the PAS helps decide whether there is reasonable cause to arrest.
The evidential breath test comes later. After a lawful DUI arrest, implied consent under section 23612 applies to a chemical test of blood or breath. That test produces the result used to support a DMV suspension and a possible charge under the 0.08 standard.
So the PAS versus breath test split comes down to purpose. One is a screening step during an investigation, while the other is a formal test after arrest. Consumer devices raise separate questions, covered in personal breathalyzer accuracy.
What the Officer Must Say Before a PAS
Section 23612(i) sets out a specific advisement. If the officer decides to use the PAS, the officer must explain that the test is to help determine whether the person is under the influence of alcohol, drugs or both. The officer must also say that the PAS does not satisfy the duty to take a chemical test after arrest.
Finally, the officer must tell the person that he or she may refuse the PAS. For most adult drivers, then, the roadside device is optional. That right to decline has two big exceptions, covered next.
Officers also observe drivers through other roadside steps. The article on California field sobriety tests covers the physical tests that often come before or after the PAS.
When the PAS Is Not Optional
Drivers under 21 face different rules. Under Vehicle Code section 13388, an officer who lawfully detains an under-21 driver suspected of drinking shall request a PAS if a device is immediately available. If no device is available, the officer may request a chemical test instead.
Section 23136 also deems an under-21 driver to have consented to a PAS or other chemical test. Its limit is 0.01 percent blood alcohol, as measured by a PAS or other chemical test. The article on California underage DUI covers that zero tolerance rule in more depth.
Similarly, section 23154 covers drivers on probation for a DUI violation. The law deems a person on that probation to consent to a PAS during a lawful detention. The same 0.01 limit applies to driving during that probation. For other terms that often come with it, see the page on California DUI probation.
Why the PAS Never Replaces the Chemical Test
Section 23612(i) states that the PAS does not satisfy the chemical test obligation. Therefore, a driver who blew into the roadside device and was then arrested still has to complete a blood or breath test. A driver who declines the later test because a PAS came first still faces the refusal rules.
In a PAS versus breath test comparison, the two readings can also differ. Time passes between them, and the body keeps absorbing or eliminating alcohol. The article on rising blood alcohol explains why a later reading can be higher or lower than an earlier one.
Choosing Breath or Blood After Arrest
For an alcohol arrest, section 23612(a)(2)(A) gives the driver a choice of blood or breath. The officer must advise the driver of that choice. If the person cannot complete the chosen test, or says so, the person must take the remaining one.
Drug suspicion changes the picture. Under section 23612(a)(2)(C), an officer may also request blood from a person who chose breath. The officer needs reasonable cause to believe drugs are involved. The officer must state the facts behind that belief in the report.
In plain terms, the DMV driver handbook says the same thing, noting that a driver may still need to give blood or urine for drugs after a PAS or breath test.
Medical exemptions also exist. A person with hemophilia, or a heart condition treated with a prescribed anticoagulant, is exempt from the blood test. Instead, that person must complete a urine test under sections 23612(b) and (c). For mixed cases, see combined alcohol and drug DUI.
How the Evidential Breath Test Is Run
Evidential breath testing follows Title 17. Under 17 CCR section 1221.2, each test includes two separate breath samples. Those results may not differ from each other by more than 0.02 grams per 210 liters of breath.
The same section requires periodic accuracy checks with reference samples of known alcohol concentration. Here, periodic means every 10 days or every 150 subjects tested, whichever comes sooner. Operators also need training, and that training must cover the required 15 minute wait period before a test.
That wait period connects to concerns about residual alcohol in the mouth. The article on mouth alcohol explains why the observation window matters. For the records an instrument leaves behind, see breathalyzer calibration records.
PAS Versus Breath Test Results and What They Show
A PAS result mainly supports the decision to arrest. For drivers under 21 and drivers on DUI probation, however, a PAS reading of 0.01 or more can itself start DMV action. Vehicle Code section 13353.2 lists those groups among the drivers who face an administrative suspension.
The evidential test result carries more weight for adult drivers. Section 23152(b) makes it unlawful to drive with 0.08 percent or more, measured in grams per 100 milliliters of blood or per 210 liters of breath. It also allows a rebuttable presumption about the level while driving if a test within three hours shows 0.08 or more.
Meanwhile, section 23610 sets presumptions for a charge of driving under the influence. Below 0.05 percent, the law presumes a person was not under the influence. From 0.05 up to 0.08, no presumption arises either way. The article on 23152(a) versus 23152(b) compares the two charges.
PAS Versus Breath Test Refusals
An adult driver who is not on DUI probation may decline the roadside PAS. In fact, the officer must tell the driver that refusing it is allowed. Even so, the officer can still rely on other observations to decide whether to arrest.
Refusing the chemical test after arrest is different. Under section 13353, a refusal leads to a one year suspension, or a two or three year revocation with qualifying priors. The officer must also explain that a refusal may be used in court. More detail is in the article on California DUI test refusal.
For under-21 drivers and drivers on probation, refusing the PAS carries its own penalty. Section 13353.1 sets a one year suspension for a first refusal, with longer revocations when there are prior refusals or violations. According to the DMV DUI page, a probationer who refuses the PAS faces a two year suspension, or a three year revocation with two or more prior offenses.
Breath Samples Are Not Kept
An evidential breath instrument does not save the breath it measures. Vehicle Code section 23614 requires the officer to tell the person this before or after the test. The officer must also offer a blood or urine sample that the agency keeps at no cost to the person.
Either side may test that retained sample in a criminal case. However, a failure to give this advisement does not, by itself, make the breath result inadmissible. The article on DUI blood retest explains how a defense lab can review a retained sample later.
An Example of the Sequence at a Stop
This example is invented for illustration and does not describe a real case. An officer stops a driver on a Sacramento street late at night. After some questions, the officer asks for a PAS and says it is voluntary. The driver agrees, and the officer then makes an arrest.
At the station, the officer explains the choice of blood or breath, and the driver picks breath. The instrument takes two samples a few minutes apart. Afterward, the officer explains that no breath sample is kept and offers a blood sample for later testing. The driver also receives a notice of suspension and a temporary license.
Each step leaves a record that a lawyer can compare with the rules above. For instance, the report should show the PAS advisement, the test choice and the timing of the evidential samples.
PAS Versus Breath Test Details to Write Down
Notes made soon after the stop help a lawyer check the PAS versus breath test steps against the report. Useful details include:
- What the officer said before the roadside device was used
- Whether the officer said the PAS could be declined
- Where and when the driver gave each breath sample
- If the officer described the choice of blood or breath
- Any mention that the instrument keeps no breath sample
- If the officer offered or collected a blood or urine sample
- Any food, drink, gum or vomiting during the wait before the test
Keep every paper received that night, including the notice of suspension and any receipt. The article on DUI questioning rights covers what drivers may decline to answer during the same stop.
Frequently Asked Questions
Can a Driver Ask for a Chemical Test After Arrest?
Yes. Section 23612(d)(1) lets a person arrested for a DUI offense ask the arresting officer for a chemical test of blood or breath. When a driver is taken to a hospital, the choice is limited to the tests that facility offers. The article on hospital blood test DUI cases covers that setting.
What Happens if a Driver Cannot Finish a Breath Test?
The driver must take the other available test. Under section 23612(a)(2)(A), a person who is unable to complete the chosen test, or says so, shall submit to the remaining test. A breathing condition is one common reason this rule comes up.
Does a Lawyer Need to Be Present Before the Chemical Test?
No. Section 23612(a)(4) requires the officer to advise that there is no right to have an attorney present before choosing or taking the chemical test. That rule applies to the post arrest test and not to later stages of the case.
Can Police Get a Blood Sample From an Unconscious Driver?
The statute allows it. Section 23612(a)(5) treats a person who is unconscious or unable to refuse as not having withdrawn consent. Constitutional limits on blood draws still apply. The article on DUI blood draw warrants covers when a warrant is needed.
How Long Is There to Challenge a Suspension From a Breath Test?
Ten days from the notice. The DMV DUI page says a driver must request an administrative hearing within 10 days of receiving the order of suspension. For the steps that follow, see DMV DUI hearing deadline and California APS suspension.
Does a Low PAS Reading End the Investigation?
Not necessarily. Section 23610(c) says the blood alcohol presumptions do not limit other competent evidence of impairment. In addition, section 23612(a)(2)(C) lets an officer seek blood when drugs are suspected, so a low alcohol reading does not close that question.
The information here is general information about California DUI law, not legal advice. Laws change, and each situation depends on its own facts.