Preliminary Alcohol Screening (“PAS”) Tests
Explained by DUI Defense Lawyers

During a California DUI investigation, the police may ask you to take up to two different types of tests to determine your blood alcohol content (“BAC”):

  1. A pre-arrest preliminary alcohol screening (“PAS”) breath test; and/or
  2. A post-arrest California DUI blood test or California DUI breath test.

The biggest difference between a pre-arrest PAS test and a post-arrest chemical test is that the PAS test is entirely optional unless:

If you do not fall into either of these categories, you may refuse a PAS test without consequence. It is simply an optional tool – like a California field sobriety DUI test – that can help a police officer decide whether to arrest you for DUI.

If you do agree, however, to take a PAS test, the results can be used against you in court.

Accordingly, if you are at least 21, and you are not on DUI probation, we recommend that you politely refuse to take a PAS test.

However, if you have been placed under arrest, refusal to to take a DUI chemical test could result in:

  • the loss of your license, and
  • enhanced DUI penalties.

For more information on this subject, please see our article, the Consequences of California DUI chemical test refusals.

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We are a firm whose lawyers include former prosecutors and cops. We now use our law enforcement experience to defend people accused of DUI throughout Southern California.

To help you better understand PAS breath testing, our California DUI defense attorneys discuss the following, below:

  1. PAS breath testing procedures
  2. PAS breath testing equipment
  3. PAS tests and drivers under 21
  4. PAS tests and drivers on DUI probation
  5. How PAS tests work
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1. PAS breath testing procedures

When an officer suspects you of driving while intoxicated, he or she will begin a California DUI investigation.

As part of this investigation, you may be asked to take a preliminary alcohol screening (“PAS) breath test. This test is optional unless:

  • You are under 21 years of age (Section 3, below), or
  • You are on probation for a prior DUI offense (Section 4, below).

If you are actually arrested for DUI, however, refusal to take a post-arrest DUI chemical test can result in:

  • a minimum one year driver's license suspension, and
  • enhanced penalties if you end up being convicted of DUI.1

By law, the police are required to tell you that a PAS breath test is optional.2 But often, they will present the PAS as if it's not a choice.

The results of a PAS test, however, can be used to help secure a DUI conviction. Accordingly, it is recommended that you politely refuse to take a PAS if you are at least 21 and not on DUI probation.

Some counties -- including Los Angeles -- have begun conducted limited tests of saliva swabs for preliminary DUI testing for drugs and alcohol.3 These tests are equivalent to the PAS breath test, except that results are not – at present – admissible in court.

Unless you are under 21, or on DUI probation, you may legally refuse a mouth swab without consequence.4

2. PAS breath testing equipment

A PAS is given on a handheld, roadside Breathalyzer or similar device.

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Handheld breath testing device for PAS breath test

A post-arrest DUI breath test, on the other hand, is usually given on a desktop device at the police station. Or, if you are arrested at a DUI checkpoint, it may be given at a mobile police unit.

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Desktop device for post-arrest DUI breath test

In some counties, post-arrest breath tests are given on the Evidential Portable Alcohol System (“EPAS”).  This system uses a Draeger Alcotest device that some police departments use for PAS tests. However, the EPAS can be hooked up to a printer by hardline or blue tooth.

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Draeger Alcotest Evidential Portable Alcohol System ("EPAS")

Orange and Ventura Counties are two of the counties known to use the EPAS for post-arrest chemical tests.

The important thing to keep in mind is not whether you are being asked to take a breath test at the station or in the field, but whether you are pre- or post-arrest. Provided you are at least 21, and you are not on DUI probation, you can refuse a pre-arrest breath test without consequence.

Once you have actually been placed on arrest for DUI, however, you may not refuse a breath test unless:

  • you have asked to take a blood test, and
  • a blood test is available.5
3. PAS tests for drivers under 21

Underage drivers can be charged with “standard” DUI:

But the California Vehicle Code also has two special sections that punish drinking and driving by motorists under age 21:

Unlike standard DUI, violations of Vehicle Code Sections 23136 and/or 23140 violations may be established by either a DUI chemical test or a PAS test.8

If you are under 21, a PAS test is not optional.9 If you refuse to take a PAS test after you are asked, you face suspension of your driver's license for at least one year.10

4. PAS tests for drivers on DUI probation

Vehicle Code 23154(a) is California's “zero tolerance” law for people previously convicted of DUI. If you are on DUI probation, you may not drive with any measurable alcohol in your system.11

Violation of California Vehicle Code 23154 may be measured by either a DUI chemical test or a PAS test.12

If you are on DUI probation, and you refuse to take a PAS test, you face suspension of your California driver's license for one to three years.13

5. How PAS tests work

Most alcohol we consume gets absorbed in our stomach and small intestine. It then passes directly into the bloodstream and is carried to our organs.14

A small amount of alcohol, however, gets excreted into our lungs.15 It is this alcohol that is measured by PAS and other breath testing devices.16

Unlike blood tests, however, breath tests do not directly measure BAC. A breath testing device must mathematically convert breath alcohol into a roughly equivalent BAC.17 For this reason, DUI breath tests are generally considered less reliable than DUI blood tests.18

Post-arrest DUI breath tests are governed by strict regulations relating to the training of breath testing operators and the maintenance of breath testing devices.

PAS tests are not, however, subject to these rules.19 As a result, PAS tests are even less reliable than post-arrest DUI breath tests.

This is just one more reason why you might want to think twice before agreeing to a PAS test if you are 21 years or older and you are not on DUI probation.

Call us for help...

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For more information about California's DUI laws, or to discuss your case confidentially with one of our criminal defense attorneys, please don't hesitate to contact us at Shouse Law Group. Our California criminal law offices are located in and around Los Angeles, Orange County, San Diego, Riverside, San Bernardino, Ventura, San Jose, Oakland, the San Francisco Bay area, and several nearby cities.

Additionally, our Las Vegas Nevada DUI defense attorneys represent clients accused of violating Nevada's DUI laws. For more information, we invite you to contact our local attorneys at one of our Nevada law offices, located in Reno and Las Vegas.

Legal references:

1 California Vehicle Code 23612(a)(1)(A) VC: 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 alcoholic content of his or her blood, if lawfully arrested for an offense allegedly committed in violation of Section 23140 [under 21 DUI], 23152 [DUI], or 23153 [DUI causing injury]…

2 California Vehicle Code 23612 (g)(2)(B)(i): If the officer decides to use a preliminary alcohol screening test, the officer shall advise the person that he or she is requesting that person to take a preliminary alcohol screening test to assist the officer in determining if that person is under the influence of alcohol or drugs, or a combination of alcohol and drugs. The person's obligation to submit to a blood, breath, or urine test, as required by this section, for the purpose of determining the alcohol or drug content of that person's blood, is not satisfied by the person submitting to a preliminary alcohol screening test. The officer shall advise the person of that fact and of the person's right to refuse to take the preliminary alcohol screening test.

3 Erika Aguilar, LA DUI checkpoints will now test for drugs with oral swab kits, KPCC Radio, December 27, 2013.

4 See same.

See also Dennis Romero, LAPD Targeting Stoned Drivers With Roadside Weed Tests, LA Weekly blogs, December 31, 2013.

5 California Vehicle Code 23612(a)(1)(A), endnote 1.

6 California Vehicle Code 23136(a) VC: Notwithstanding Sections 23152 and 23153, it is unlawful for a person under the age of 21 years who has a blood-alcohol concentration of 0.01 percent or greater, as measured by a preliminary alcohol screening test or other chemical test, to drive a vehicle. However, this section shall not be a bar to prosecution under Section 23152 or 23153 or any other provision of law.

See also Coniglio v. Department of Motor Vehicles (1995) 39 Cal. App. 4th 666, 46 Cal. Rptr. 2d 123 (“[I]t is a legal impossibility to express a blood-alcohol concentration below 0.01 percent. To do so would require reporting to the third decimal place. The provision that blood-alcohol concentration less than 0.01 percent shall be reported as negative is tantamount to recognizing that 0.01 percent is the threshold level for reporting the presence of alcohol.”).

7 California Vehicle Code 23140(a) VC: It is unlawful for a person under the age of 21 years who has 0.05 percent or more, by weight, of alcohol in his or her blood to drive a vehicle.

8 California Vehicle Code 13388(a): If a peace officer lawfully detains a person under 21 years of age who is driving a motor vehicle, and the officer has reasonable cause to believe that the person is in violation of Section 23136, the officer shall request that the person take a preliminary alcohol screening test to determine the presence of alcohol in the person, if a preliminary alcohol screening test device is immediately available. If a preliminary alcohol screening test device is not immediately available, the officer may request the person to submit to chemical testing of his or her blood, breath, or urine, conducted pursuant to Section 23612.

9 California Vehicle Code 23136(c)(1): Any person under the age of 21 years who drives a motor vehicle is deemed to have given his or her consent to a preliminary alcohol screening test or other chemical test for the purpose of determining the presence of alcohol in the person, if lawfully detained for an alleged violation of subdivision (a).

10 California Vehicle Code 23136(c)(3): The person shall be told that his or her failure to submit to, or the failure to complete, a preliminary alcohol screening test or other chemical test as requested will result in the suspension or revocation of the person's privilege to operate a motor vehicle for a period of one year to three years, as provided in Section 13353.1.

See also California Vehicle Code 12802.5(a)(3): A refusal to take, or a failure to complete, a preliminary alcohol screening test or other chemical test for the purpose of determining the level of alcohol pursuant to Section 13388 shall result in a one-year suspension of the driving privilege.

11 California Vehicle Code 23154(a) It is unlawful for a person who is on probation for a violation of Section 23152 or 23153 to operate a motor vehicle at any time with a blood-alcohol concentration of 0.01 percent or greater, as measured by a preliminary alcohol screening test or other chemical test.

12 Same.

13 California Vehicle Code 23154 (c):

(1) A person who is on probation for a violation of Section 23152 or 23153 who drives a motor vehicle is deemed to have given his or her consent to a preliminary alcohol screening test or other chemical test for the purpose of determining the presence of alcohol in the person, if lawfully detained for an alleged violation of subdivision (a).

…(3) The person shall be told that his or her failure to submit to, or the failure to complete, a preliminary alcohol screening test or other chemical test as requested will result in the suspension or revocation of the person's privilege to operate a motor vehicle for a period of one year to three years, as provided in Section 13353.1.

14 MedicineNet.com, How is Alcohol Metabolized?

15 Same.

16 See Ralph Hingson and Michael Winter, Epidemiology and Consequences of Drinking and Driving, National Institute on Alcohol Abuse and Alcoholism.

17 The American Association for Justice, Challenging the DUI Breath Test: Breath Testing Basics and Factors Affecting the Test.

18 Patrick T. Barone and Jeffery S. Crampton, Blood Alcohol Testing: Understanding quantitative blood alcohol testing in drunk driving cases, Michigan Bar Journal, August 2003.

See also Sidney Kaye, The Collection and Handling of the Blood Alcohol Specimen, American Journal of Clinical Pathology, Vol. 74, No. 5, November 1980 (DUI blood tests have an inherent range of error of about .005 % BAC; while breath test instruments have an inherent range of error of about .01 % to .02 %).

19 These regulations are set for in Title 17 of the California Code of Regulations.

See also, Coniglio v. Department of Motor Vehicles, endnote 6 (“California Code of Regulations title 17 regulations do not apply to the PAS test”).

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