The Law Firm of Starzynski Van Der Jagt, P.C.
A Professional Corporation of Attorneys & Counselors at Law in Colorado and Wisconsin
Breathalyzer Q & A

Bias In The Breath Alcohol Test

The initial intent of the legislature was to provide a law that could make it much easier to prosecute by taking away the possibility of defense arguments concerning the variability between BrAC and BAC . In fact, the passage of the "breath per se" law has made it much more difficult for prosecution by virtue of a lack of definition of breath. In fact the average BrAC is actually much lower than any breath alcohol test machine reading. In effect, the legislature has dealt a blow to the prosecution because it is now impossible for the prosecution to prove that the average BrAC is greater than or equal to a given standard, whether it is 0.08 gm/210 L or 0.10 gm/210L.

The technology in the roadside PAS test is called "fuel cell" technology. This technology works by burning up the alcohol, which generates an electrical current that is measured and quantified with a numeric result. The technology in these roadside PAS tests is dubious at best. These devices do not have "slope" detectors, which are designed to guard against mouth alcohol causing an artificially high reading by detecting a negative slope (or sharp drop-off) in the alcohol level; they are not specific for alcohol, and are subject to error due to certain types of chemical buildup.

Our DUI defense lawyers and DWAI defense attorneys are often asked why they are taking a particular drunk driving case to trial, when a breath analysis machine has produced a reading above the legal limit. What these drunk driving lawyers know, and what they hope to educate their juries about, is that the breath testing machines that are used in DUI and DWI arrests are subject to error even in the best of circumstances. Breath testing in drunk-driving cases is far from perfect. For instance, the breathalyzer reads significantly higher if the test taker holds its breath just before blowing into the breathalyzer device.

Nonetheless, even if you pass or disqualify a breathalyzer, you can still be convicted:

The problems with the breathalyzer stretch all the way back to the beginning of the test. Breath testing in DUI cases dates back to 1937, when Rolla Harger invented the "Drunkometer". This machine gave birth to an industry that has witnessed many new designs, each trying to improve on the reliability of its predecessor. However, even in our present era, every single breath-testing device is subject to mistakes. All breath-testing machines used in DUI and DWAI cases make certain assumptions about the people being tested that may or may not be true. All of the drunk-driving, breath-testing machines are subject to human error, maintenance problems, interference from outside sources (such as radio frequency interference), and internal malfunctions.

DUI breath testing is an indirect way of determining blood alcohol content (BAC) or blood alcohol level (BAL). Many states have tried to get around the obvious problems associated with converting a breath alcohol level to a blood alcohol level by outlawing driving above a certain limit as determined by either a blood or breath test. As a result of the incongruence between the tests and ones impairment, Colorado DUI and DWAI lawyers, and the ACLU, constantly confront laws that make it illegal to drive while under the influence of alcohol, or to drive with a blood or breath alcohol level of .08% or higher. The former is based on actual impairment; the latter is based only on the subject's alcohol level, without regard to whether or not they are actually feeling the effects of drinking alcohol.

Breath testing for alcohol is typically accomplished either on a roadside test prior to arrest, or on a more stationary machine at the jail following arrest. The portable device, which is a little bigger than a pack of cigarettes, is called a Preliminary Alcohol Screening (PAS) test, or Preliminary Breath Testing (PBT) device. In Colorado, the officer conducting the investigation is supposed to tell the DUI or DWAI suspect that blowing into the PAS device is optional. In practice, this is done inconsistently, at best and is often accompanied by police duress or intimidation.

The technology used in the stationhouse breath testing devices is slightly more reliable, in that they do typically have slope detectors to guard against mouth alcohol contamination, but are subject to human, internal, and external error as well. The stationhouse breath testing machines may use a fuel cell, or an infrared system to measure alcohol levels. Where an infrared system is used, the breath sample is blown into a chamber, and an infrared beam is shot from one end to the other. The beam is absorbed by alcohol molecules (and other molecules in the same spectrum, unfortunately), and the amount the beam is diminished as it passes from one end of the sample chamber to the other is measured, and is expressed in a numeric value. The greater the amount of light that is absorbed from one side of the chamber to the other, the higher the reading on the machine.

Unfortunately for those who stand accused of DUI, DWAI, or any other drinking and driving related offense, the ways in which the breath testing machines can be in error are many indeed. They include problems with mouth alcohol causing artificially high results, non-specificity to alcohol (where other compounds are mistaken for alcohol by the machine), radio frequency interference, calibration errors, human error, and more.

If you or someone you care about is charged with DUI, DWAI, or some type of drunk driving offense, it is critical that you contact a lawyer that is familiar with the errors associated with breath testing. Understanding the types of errors that are common, and investigating all the potential problems, is the first step in a successful defense to a DUI.


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