What is the Difference between a PAS Test and a Chemical Test?

Posted by Jon Ibanez on January 25th, 2016

Most people are unaware that many California DUI stops include two separate and distinct breath tests. And people are often confused about whether they must provide a breath sample to both or either test. It is admittedly confusing, and most people are surprised when I tell them that one of the breath tests is required and the other is not.

The two tests I am referring to are 1.) the preliminary alcohol screening test (PAS test), and 2.) the chemical breath test. While they are both “breathalyzer” tests, their distinction lies in when the DUI arrest is made.

According to California Vehicle Code section 23612(h), the PAS test “indicates the presence or concentration of alcohol based on a breath sample in order to establish reasonable cause to believe the person was driving [under the influence]…[it] is a field sobriety test and may be used by an officer as a further investigative tool.”

Following a California DUI stop, but before a DUI arrest, an officer may request that the suspected drunk driver perform field sobriety tests which, most people know, includes the horizontal gaze nystagmus test, the walk-and-turn test, and the one-leg stand test. What most people don’t know, however, is that the breathalyzer test requested by officers before an arrest is also a field sobriety test. This is the PAS test. And like the other field sobriety tests, the PAS test is optional.

The investigating officer must advise the DUI suspect that the PAS test is, in fact, optional. California Vehicle Code section 23612(i) states that “If the officer decides to use a [PAS], the officer shall advise the person that he or she is requesting that person to take a [PAS] test to assist the officer in determining if that person is under the influence. The person’s obligation to submit to a [chemical test under California’s Implied Consent Law] is not satisfied by the person submitting to a [PAS] test. The officer shall advise the person of that fact and of the person’s right to refuse to take the [PAS] test.”

Field sobriety tests, including the PAS test, are a means to determine if the officer has the required probable cause to arrest the DUI suspect for a California DUI.

If the officer has the requisite probable cause to make an arrest, whether through the field sobriety tests, the PAS test, or any other information, California’s Implied Consent Law kicks in. Herein lies the difference between a PAS test and a chemical test.

California Vehicle Code section 23612(a)(1)(A) sets forth the Implied Consent requirement. “A person who drives a motor vehicle is deemed to have given his or her consent to chemical testing of his or her blood or breath for the purpose of determining the alcohol content of his or her blood, if lawfully arrested for an offense allegedly committed in violation of [California’s DUI laws].”

In other words, licensed California drivers have impliedly consented to provide a chemical test following a lawful DUI arrest.

The post-arrest chemical test can be either a breath test or a blood test. If a person opts against providing blood, they must provide a breath sample. And for this breath test, they will be taking a breathalyzer very much like the PAS test.

The short version of this article is this: A pre-arrest PAS test is optional and you should always politely decline this test. A post-arrest chemical breath test is required provided the suspect opts not to provide a blood sample and provided that the arrest was lawful.

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