Defenses to a Breath Test DUI Case


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Defenses to a Breath Test DUI Case

Defenses to a Breath Test DUI Case

Breath Test Defenses in a DUI

A breath test using a machine is not the end in a DUI case.  There are certainly Defenses to a Breath Test DUI case. For one, the breathalyzer machine is calibrated to the “average” person, even though in the real world of testing, there is no such thing.

Breathalyzer False Positive Factors Include the Following:

The Law of Breath Testing

Breath testing may, and may not be, mandatory, depending on the type of test performed.  A preliminary alcohol screening device, used as part of the field sobriety testing, to show the presence of alcohol, which is typically not subject to the same strict calibration and maintenance (and internal electronic checks) as an evidentiary breath test, can be refused without consequence, as all field sobriety tests can.

The exception is for those persons that are under 21 or are already on DUI probation for a conviction of Vehicle Code section 23152(a) and 23152(b), or Vehicle Code section 23103.

When a person driving a vehicle is arrested for driving under the influence, he or she is required by law to submit to a test of blood alcohol or face a one year suspension of his driver’s license, or two years if previously convicted of 23152, 23153 or 23103 CVC, within the last ten years of the date of admonition (23612 CVC / 13353 CVC), as part of the conditions of your driving privileges under California Law.

The Science of Breath Testing –  How Breath Testing Works

Breath testing devices use a fuel cell, for the most part, to heat up the air and measure the alcohol captured and measured, as a percentage of the total breath captured.

In 1954, Indiana State Police employee Dr. Robert Borkenstein invented the Breathalyzer, a type of breath alcohol testing device that is still used by law enforcement agencies today.  Because all laws regarding DUI require that drivers be below a certain blood alcohol level, breath testing devices have to assume certain averages (like lung capacity), to convert that to what a blood level is assumed to be.

The Requirements for Breath Testing

The requirements for breath testing, which are made the law in Title 17, the State’s Alcohol Testing code, requires all of the following to be a valid breath test for alcohol.

  1.  The DUI breath test must have been taken within three hours of driving.
  2. The DUI breath test must have been taken using an officially approved measuring device.
  3. The DUI breath testing machine or device must have been maintained as approved by the manufacturer’s maintenance schedule.
  4. The DUI breath test must have been taken after the subject has been observed continually for fifteen (15) minutes, during which the subject has not “belched, burped, or vomited”.
  5. The DUI breath test assumes that the subject has the average Blood Breath Partition Ratio (which averages that  2100mL of breath contain the same amount of alcohol as 1 mL of blood). That figure was given as an average figure over 45 years ago by the National Safety Council’s Committee for Tests on Intoxication.
  6. The testing subject or driver must not have GERD (acid reflux), diabetes, asthma, bronchitis, or any contaminants, including breath strips, mouthwash, dental work that traps alcohol, food in the teeth, or any acetones.  Acetones are a well known false positive for alcohol in breath tests and can be gathered in the lungs by working around paints or solvents, or by air bag dust from an auto accident.
  7. The testing subject or driver must have a standard temperature of plus or minus one degree from 34 degrees Celsius.  Having a fever, being on certain medications, trauma from an accident, exercise, or certain times of a menstrual cycle, can affect temperature.
  8. The testing device or machine must be kept at a constant temperature and must be able to adjust for atmospheric pressure, altitude, or temperature changes.
  9. The testing device or machine must be kept free from radio waves or electrical interference, which can affect the operation of the testing device, including officer radio equipment, and including cell phones.
  10. The testing device or machine must be on its own power supply, not a shared power supply with any other device.
  11.  The testing device or machine MUST be calibrated every 10 days, or every 150 uses, whichever comes first under the Title 17 law (below).
  12. The officer using the breath testing device or machine must have been specifically trained on that particular device.
  13. The breath test must follow the “2/2/2” law.  That is, the machine or device must take two acceptable breath machine samples, separated in time by at least two minutes, and those two samples must agree within a .02% of each other.

DUI Breath Testing - AlcoSensor IV Breathalyzer

Defenses to a Breath Test DUI Case

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Defenses to a Breath Test DUI Case can exist and can lead to a dismissal of a DUI case, or a reduction of a DUI case.  Call our office, or Contact Us, for information on your particular case. 

(Footnote: Title 17 reads as follows regarding breath testing--

§1221.4. Standards of Procedure. (a) Procedures for breath alcohol analysis shall meet the following standards: (1) For each person tested, breath alcohol analysis shall include analysis of 2 separate breath samples which result in determinations of blood alcohol concentrations which do not differ from each other by more than 0.02 grams per 100 milliliters. (2) The accuracy of instruments shall be determined. (A) Such determination of accuracy shall consist, at a minimum, of periodic analysis of a reference sample of known alcohol concentration within accuracy and precision limits of plus or minus 0.01 grams % of the true value; these limits shall be applied to alcohol concentrations from 0.10 to 0.30 grams %. The reference sample shall be provided by a forensic alcohol laboratory. 1. Such analysis shall be performed by an operator as defined in Section 1221.4 (a)(5), and the results shall be used by a forensic alcohol laboratory to determine if the instrument continues to meet the accuracy set forth in Section 1221.4 (a)(2)(A). (B) For the purposes of such determinations of accuracy, "periodic" means either a period of time not exceeding 10 days or following the testing of every 150 subjects, whichever comes sooner. (3) Breath alcohol analysis shall be performed only with instruments for which the operators have received training, such training to include at minimum the following schedule of subjects: (A) Theory of operation; (B) Detailed procedure of operation; (C) Practical experience; (D) Precautionary checklist; (E) Written and/or practical examination. (4) Training in the procedures of breath alcohol analysis shall be under the supervision of persons who qualify as forensic alcohol supervisors, forensic alcohol analysts or forensic alcohol analyst trainees in a licensed forensic alcohol laboratory. (A) After approval as set forth in Section 1218, the forensic alcohol laboratory is responsible for the training and qualifying of its instructors. (5) An operator shall be a forensic alcohol supervisor, forensic alcohol analyst, forensic alcohol analyst trainee or a person who has completed successfully the training described under Section 1221.4 (a) (3) and who may be called upon to operate a breath testing instrument in the performance of his duties. (6) Records shall be kept for each instrument to show the frequency of determination of accuracy and the identity of the person performing the determination of accuracy. (A) Records shall be kept for each instrument at a licensed forensic alcohol laboratory showing compliance with this Section.


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