DUI Breathalyzer Accuracy

In many DUI cases, breath analysis is the method used to test for blood alcohol concentrations. Many scientists have conducted studies regarding breath alcohol analysis and most have agreed with Dr. Hiastala in concluding that breathalyzer accuracy is inherently unreliable. Dr. Michael Hiastala, Professor of Physiology, Biophysics and Medicine at the University of Washington comments:

“Breath testing, as currently used, is a very inaccurate method for measuring BAC. Even if the breath testing instrument is working perfectly, physiological variables prevent any reasonable accuracy…. Breath testing for alcohol using a single test method should not be used for scientific, medical or legal purposes where accuracy is important.” [Hiastala, Physiological Errors Associated with Alcohol Breath Testing, 9(6) The Champion 19 (1985).]

In many studies, it is estimated that at least one court has reserved DUI convictions on the grounds that breathalyzers accuracy unreliable. There are four “safeguards” for breath testing according to Dr. Dubowski. He has been a longtime advocate to strict procedures for reducing the many sources of error in DUI breath testing.

  1. A pre-test deprivation-observation period of at least 15 minutes.
  2. Blank tests immediately preceding each breath specimen collection step.
  3. Analysis of at least two separate consecutive breath specimens, taken two to ten minutes apart (different results from duplicate analysis may indicate such problems as radio frequency interference).
  4. An appropriate control test accompanying every subject test.

The National Safety Council Committee on Alcohol and Drugs has recommended at least two separate breath samples be collected and analyzed individually. At least two separate breath samples should be collected and analyzed individually in performing any evidential breath alcohol analysis. Tests should be collected at intervals of more than 2 and no more than 10 minutes. All results should be obtained and reported.

Breath analyzing is the most economical method in any DUI investigation. There are many different breath analyzing machines in use today: Intoxilyzer 5000, Intoxilyzer 9000, BAC DataMaster, Intoximeter EC/IR, Draeger AlcoTest 7110 and the portable Draeger AlcoTest 7410.

All of these machines use their own mechanism for analyzing the alcohol content except the Breathalyzer. The Breathalyzer employs the “wet chemical” technique. The other machines use a method called infrared spectroscopic analysis, the principal that alcohol vapor captured in a chamber will absorb light waves of a certain frequency when beamed through it.

California DUI defense attorneys should be aware there are a various of problems in approaching a DUI case involving a breath analysis.

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