California DUI Breath Testing is Subject to a Wide Variety of Errors

Although breath testing is the most common way to measure an individual’s blood alcohol concentration ("BAC"), it is subject to a wide variety of testing errors that may render the results unreliable. This is one of the reasons why police may falsely arrest (and prosecutors wrongfully convict) innocent people for DUI.

Even when your breath test reports that you have a BAC of 0.17%...more than twice the legal limit...if we can show the result is inaccurate, it doesn’t mean a thing.

The science behind California DUI breath testing instruments

California law enforcement agencies use several different DUI breath testing instruments, but each device operates on infrared spectroscopy and/or fuel cell technology. Both these technologies convert the amount of alcohol that is present in an individual’s breath into the amount of alcohol that is in that person’s blood.

This indirect conversion process frequently causes the integrity of DUI breath test results to be compromised. Factors such as

• one’s physiology,



• the environment, and



• procedural errors

often compound the problem, leading to a large number of false DUI arrests.

A good California DUI defense lawyer is aware of these problems and knows how to convince a prosecutor, judge, and/or jury that...when present...any or all of these factors could produce an inaccurately high BAC result.

Procedural errors can affect the accuracy of DUI breath testing instruments

Procedural errors are one of the reasons why California DUI breath testing instruments are frequently inaccurate. When proper procedures aren’t strictly adhered to, countless problems can arise. Examples of procedural errors include (but are not limited to):

• breath testing equipment failure or malfunction,



• Title 17 violations (Title 17 of the California Code of Regulations sets forth the requirements for collecting, storing, and analyzing California DUI chemical tests), and



• improper police procedure and/or misconduct.

When these...or any other...procedural violations occur, a skilled California DUI defense attorney knows how to challenge the accuracy of the reported breath test results.

If, for example, the result of your breath test is a 0.11% (but the instrument on which you took your test hadn’t been properly maintained or calibrated in accordance with Title 17), that 0.11% could in fact be a 0.06%...which is well below California’s 0.08% threshold¹.

Physiological factors can affect the accuracy of DUI breath testing results

There is no such thing as an "average" individual...at least not when it comes to DUI breath testing. As Los Angeles DUI defense attorney John Murray explains², "California DUI breath testing instruments simply aren’t advanced enough to adjust for individual body chemistry or make-up. As a result, a wide variety of physiological factors can adversely affect the results of a DUI breath test."

Physiological factors such as

• a rising blood alcohol level ("rising blood alcohol" is a DUI defense when the alcohol in your system isn’t fully absorbed at the time of your DUI chemical breath test),



• mouth alcohol ("mouth alcohol" acts as a DUI defense when alcohol that is present in your mouth masks the deep lung or "alveolar" air that California breath testing instruments are designed to measure),



• GERD, heartburn, or acid reflux (GERD, heartburn, and acid reflux are medical DUI defenses, in that each of these recognized medical conditions produces a possible mouth alcohol situation), and/or



• certain diets (an Atkins-style low-carbohydrate / high-protein diet can "trick" the DUI breath testing instrument by auto-producing isopropyl alcohol...which is mistaken by the testing device for ethyl alcohol, the type of alcohol we consume in alcoholic beverages),

can all cause a breath testing instrument to produce a falsely high BAC result. This is because California DUI breath testing devices aren’t typically sophisticated enough to distinguish between

1. deep lung air and alcohol that remains in the mouth, or



2. ethyl alcohol and isopropyl alcohol.

Because of this flaw in technology, either of these situations will likely produce a falsely high BAC. This is why it is critical to divulge everything to your California DUI defense lawyer.

Be sure to discuss any and all dietary issues and medical conditions, even if you don’t think they are relevant to a DUI. If the attorney specializes in DUI defense, allow him/her to determine what evidence is irrelevant...and what might just be the key to securing your acquittal.

Miscellaneous factors can also contribute to falsely high BAC results on DUI breath tests

In addition to the above factors that can also result in inaccurate BAC readings, there are a variety of miscellaneous factors that produce falsely high results as well.

• Environmental factors such as radio frequency interference ("RFI" is a type of electromagnetic interference which...when intercepted by a DUI breath testing machine...will contaminate the BAC results), and



• inherent error rates within DUI breath testing instruments (which are scientifically validated discrepancies of up to 0.02% in one’s true BAC)

are also likely to affect the accuracy of breath testing instruments. Both of these factors are discussed in more detail in our article entitled "20 Ways to Beat a California DUI".

If you have additional questions about California DUI breath testing instruments, or you would like to discuss your case confidentially with a California DUI defense attorney, please don’t hesitate to contact us at Shouse Law Group. We have local DUI law offices in and around Los Angeles, San Diego, Orange County, Riverside, San Bernardino, Ventura, San Jose, Oakland, the San Francisco Bay area, and several nearby cities.

You may also find helpful information in our related articles on how Title 17 of the California Code of Regulations sets forth the requirements for collecting, storing, and analyzing California DUI chemical tests, how GERD, heartburn, and acid reflux are medical DUI defenses, how an Atkins-style low-carbohydrate / high-protein diet can "trick" the DUI breath testing instrument, how "Mouth Alcohol" acts as a DUI defense, how "Rising Blood Alcohol" is a DUI defense, and 20 Ways to Beat a California DUI.

Legal References:

¹California Vehicle Code 23152 -- Driving under the influence. ("(a) It is unlawful for any person who is under the influence of any alcoholic beverage or drug, or under the combined influence of any alcoholic beverage and drug, to drive a vehicle. (b) It is unlawful for any person who has 0.08 percent or more, by weight, of alcohol in his or her blood to drive a vehicle. For purposes of this article and Section 34501.16, percent, by weight, of alcohol in a person's blood is based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.")

²Los Angeles DUI defense attorney John Murray represents clients accused of driving under the influence throughout L.A. County, including Beverly Hills, Burbank, Glendale, Lancaster, Long Beach, Los Angeles, Pasadena, Pomona, Torrance, Van Nuys, West Covina, and Whittier. You can contact us at Shouselaw at (888) 327-4652.

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