DUI Breathalyzer Accuracy

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At least one court has even reversed DUI convictions on the grounds that breathalyzer accuracy is inherently unreliable. In State v. McGinley, 550 A.2d 1305 (NJ. Super. 1988), the New Jersey Superior Court, Law Division, considered the consolidated appeals of four DUI defendants whose convictions involved Breathalyzer tests. Although noting that the New Jersey Supreme Court had essentially taken judicial notice that the Breathalyzer models "900 and 900A are scientifically reliable," the court nevertheless felt free to consider new scientific evidence not previously available - evidence based in large part on the work of Dr. Kurt Dubowski:

The scientific evidence upon which the defendants rely shows the following: (1) The breathalyzer is designed to test persons having a 2100/1 blood-breath ratio. Such ratios in fact vary from 1100/ 1 to 3200/i and the variance can produce erroneous test results. High readings are produced in 14% of the population. (2) The temperature of the machine itself varies, affecting test results. (3) Body temperatures vary, affecting test results. (4) Hematocrit (the solid particles in whole blood) levels vary, particularly between males and females, affecting test results. These sources of error make breathalyzer test results suspect and, to insure reliability, require the substantial reduction of blood-alcohol percentages based on a translation of those results. The leading expert in the field, recognized as such by both State and defense, is of the opinion that the reduction should be .055. [550 A.2d at 1306.]

Dr. Dubowski has long advocated strict procedures for minimizing the many sources of error in DUI breath testing. One article entitled Quality Assurance in Breath-Alcohol Analysis, 18 Journal of Analytical Toxicology 270 (October 1994), he identified four "necessary safeguards" for 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.

Due largely to the inherent unreliability of breath analysis in DUI cases, the National Safety Council Committee on Alcohol and Other Drugs has recommended that at least two separate breath samples be collected and analyzed individually. As reported in a letter from Dr. Dubowski published in 9 American Journal of Forensic Medical Pathology 272 (1988), the Committee further recommended that the breath samples be collected at intervals of at least two and not more than ten minutes. This process of duplicate analysis has been widely advocated by experts in the past, most notably (and vociferously) by Dr. Richard Jensen. A 1995 Colorado Department of Health study indicates that, as of that time, 26 states provided for duplicate breath analysis in DWI investigations, while 22 required only a single analysis. Of the 26 requiring two tests, 14 accept the lower of the two as the legal result and two states average the two results; most require that the two results be within .02 of one another. The material on duplicate breath testing referred to is the following:

At least two separate breath samples should be collected and analyzed individually in performing any quantitative evidential breathalcohol analysis. The breath samples should be collected at intervals of not less than 2 nor more than 10 minutes, after an initial deprivation period of at least 15 minutes. Reported breathalcohol analysis results shall be truncated to two decimal places; and all results obtained shall be reported. Consecutive breathalcohol analysis results within 0.02 g/2lO L without regard to sign, shall be deemed to be in acceptable agreement.

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