Santa Barbara Dui Lawyer Answers Faq On Ca Breath Tests And Breathalyzer Testing
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Santa Barbara DUI Lawyer Answers FAQ on CA Breath Tests and Breathalyzer Testing

As a Santa Barbara DUI Lawyer I am often asked, “why did the officer make me take the breath test over and over?”. In the course of a DUI Santa Barbara cops may administer two different breath tests: yes, two different tests. The two different tests are theoretically performing the same tasks, however they have different legal requirements, regulations, and ramifications.

Santa Barbara DUI attorney breath test

The first test; a preliminary alcohol screening (“PAS”) breath test given on a handheld, roadside breathalyzer. This is given before a driver is arrested.

The second test; is an evidentiary breath test either on a desktop breathalyzer, or on a handheld breathalyzer. This test comes after a driver is arrested for a DUI, then officers can require you to submit to a chemical test. You may not refuse this test without consequence. Even if you have already taken a preliminary breath test, you must take a post-arrest chemical test.

To further complicate of these two different breath tests, is the second of these two different tests requires that two samples be taken two minutes apart. So if you are arrested for a Santa Barbara DUI statistics suggest you may be asked several, and I repeat several questions if you chose a breath test, and the specifics of the breath testing. Of course, the DUI arrest report will often clarify if these two different breath tests were administered.

Additionally, there may be additional tests administered either PAS or evidentiary breath because of the necessary sample size needed for a completed test. According to the normal volume the average user breathes into a breathalyzer during a five second sample is about 5,000 mL. The first 3,500 mL is disregarded because it comes from the mouth and esophagus. It’s only in the last second or so of the sample that the air pump opens and pushes the final 1,500 mL across the sensor. This ensures the air is all coming from one direction, which is important for accuracy, and also only allows air from the deepest part of the lungs to be tested.


The first; a preliminary alcohol screening (“PAS”) breath test given on a handheld, roadside breathalyzer. This is given before a driver is arrested. California Highway Patrol officers and local law enforcement are equipped with hand-held breath testing instruments. These are used to conduct Preliminary Alcohol Screening (PAS) tests to measure the BAC of suspected Drunk Driving. The CHP also uses them in suspected cases of driving under the influence of drugs to counter a driver’s contention that his or her alleged impairment is due to alcohol.  A Santa Barbara drunk driver may be offered a hand-held PAS test when pulled over. It is a field sobriety test

So what’s the low down on this first test (the PAS test)? It is optional. Yes! it is optional! Though it is not the same as the implied consent, post arrest chemical (breath test).

California Vehicle Code 23612(i) provides;

“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….

The officer shall advise the person of that fact and of the person’s right to refuse to take the preliminary alcohol screening test.”

You may decline to take the PAS, unless:

  • You are under the age of 21 (Underage DUI penalties are different than over 21), or
  • You are on probation for DUI.

The second test; is an evidentiary test, either on a desktop breathalyzer, or on a handheld breathalyzer. If you actually get arrested for a DUI, then officers can require you to submit to a chemical test. You may not refuse this test without consequence. Even if you have already taken a preliminary breath test, you must take a post-arrest chemical test. Adding further to the confusion of the two types of breath tests some law enforcement use the same breathalyzer. This breathalyzer known as the Evidential Portable Alcohol System (“EPAS”).  The general difference is the ability to print the results and the truncated results readout. In the evidentiary mode, results are shown in two decimals, and in Preliminary mode results are shown in three decimals (i.e.: .12% vs. .123%).

Title 17 of the California Code of Regulations sets forth the rules that police must follow in connection with DUI breath tests. These rules include (but are not limited to):

  • California-approved DUI breath testing devices,
  • Calibration and testing of such devices,
  • Training of persons administering the DUI breath test,
  • A 15-minute continuous observation period before the test is started (during which time you must not eat, drink, smoke or vomit),
  • Two separate breath test results which differ by no more than 0.02 grams per 100 milliliters of blood alcohol, and
  • Proper record keeping at each stage of instrument calibration, the arrest, and the breath test.


There is no widespread consensus among Santa Barbara Dui Lawyers as to which method, blood or breath test is more advisable. Find a DUI Lawyer, and ask, the answer will be “it depends.”  On the one hand, DUI breath testing is generally considered less reliable and less accurate than blood testing. As will be explained below, breath tests are prone to a host of errors that may — and frequently do — render falsely high readings.

Moreover, unlike blood samples, breath samples cannot be preserved. Thus even the best Dui Lawyer has no way to conduct later independent testing to verify the accuracy of the test.

On the other hand, these issues may be used by the Santa Barbara DUI Attorney to attack the breath test evidence in court.

The theory of breath testing is that alcohol that a person drinks shows up in the breath because it gets absorbed from the mouth, throat, stomach and intestines into the bloodstream. Alcohol is not digested upon absorption or chemically changed in the bloodstream. As the blood goes through the lungs, a physiologically predictable amount of the alcohol will move across the lung membranes and into the lungs themselves. Once in contact with the air in the lungs, it evaporates and is exhaled. The concentration of the alcohol in the air in the lungs is directly related to the concentration of the alcohol in the blood.

There is a presumed ratio of breath alcohol to blood alcohol, which is is 2100 to 1 (and called the partition ratio) in California, so the alcohol content of 2100 milliliters of exhaled air will be the same as for 1 milliliter of blood. The partition ratio can vary between 1700 and 2400 depending upon the individual and local environmental conditions, leading to a breath analysis reporting either a higher or lower calculated blood alcohol reading. Since it is a physiological response, the partition ratio can be raised or lowered by body Temperature and cellular composition of blood.

Other factors affecting breathalyzer accuracy are that Breathalyzers only estimate the BAC, not physically measure it. Some breathalyzers can’t differentiate between ethyl alcohol and other compounds of a simple chemical nature. Methyl compounds such as acetone and ketones can be present in the breath of diabetics and those taking dietary supplements, causing the breathalyzer to over-estimate the BAC. Breathalyzers assume that the alcohol concentration in the breath will be the same as in the blood, and that the breath is sourced from deep in the lungs, but the breath alcohol concentration can be increased by vomit or blood in the mouth, acid reflux, or simply having had a drink recently with alcohol residue from that drink still being in the mouth at the time of testing. Mouthwash or breath freshener often contain alcohol, so don’t use these in an attempt to disguise the smell of alcohol when being pulled over. Absorption of alcohol into the blood may lag actually drinking it by as much as 1-2 hours so even though you may have alcohol in your breath, if you’ve only consumed it recently it may not be in your bloodstream in the concentration that testing your breath indicates.

There are certain medical conditions – such as asthma, emphysema, and unconsciousness – may prevent you from taking a breath test altogether.

So breath testing does not directly measure your blood alcohol. Breath testing devices have to mathematically convert the amount of alcohol present in your breath into the amount of alcohol estimated to be present in your blood. These will be issues in any DUI trial with breath test evidence, and DUI reckless driving, DUI suspension hearings, and DUI plea bargain efforts.

If you have been arrested for DUI Santa Barbara Attorney Kenneth M. Hallum offers a free case consultation. Call today 805-564-3101. Know your rights, options and defenses against drunk driving.

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