DUI Breath-Alcohol Tests
Breath analysis (breathalyzer testing) is by far the most commonly used method of testing for blood
alcohol in DUI cases. While it is not as accurate or reliable as blood tests, it has generally been
regarded in the scientific community as acceptably accurate if administered correctly. In defending
a DUI case, challenging the correct administration of breath testing is frequently the difference between
a guilty finding and a not - guilty finding.
Effective breath test challenges can come on two different fronts. The first of these is to mount a challenge
to the breath testing procedures used by showing that they did not comport with procedures required under
the Illinois Administrative Code. The second method is to attack the underlying science of the breath-test
procedures. Understanding all aspects of both these methods is not a simple task and the great majority
of lawyers have very little working knowledge of either.
Irrespective of which method is used to challenge breath-alcohol analysis, it is important to keep in mind
the legal context in which the challenge is brought. Remember - most DUI cases have two distinct aspects:
The Statutory Summary Suspension Aspect and the Criminal Aspect. Because the burden of proof is
different in each of these aspects, there can be very different results in each when mounting a challenge
to breath tests. In the Summary Suspension hearing the burden of proof is on the driver to show that the
breath tests were not accurate. In the criminal aspect of the DUI case the burden of proof is on the Prosecution.
Moreover, in the criminal aspect of the case, the driver charged with a DUI can choose either a jury trial or
a bench trial. In the Summary Suspension aspect there is no such choice - only the judge will decide (assuming
there is no agreement with the prosecution).
Common Challenges to Breath Testing Procedures
Challenging breath test procedures is generally based on
identifying inconsistencies between the way a police officer
has conducted the test and the prescribed rules for conducting the tests established by the Illinois State Police and
codified into law under the Illinois Administrative Code.
Brent Christensen has successfully challenged breath tests by showing the follwing procedural rule violations:
- The Breath Testing Instrument was not certified accurate within 62 days before a subject test
- The Breath Testing Instrument was not certified accurate within 62 days after a subject test
- The Breath Test Operator did not conduct a twenty-minute observation period of the subject immediately before the test
- The Breath Test Operator did not have the proper certification to conduct the test
- The Technician responsible for certifying the instrument was not himself properly certified to do so
In making challenges to breath testing based on procedural flaws it is not always essential to offer testimony of an
expert witness. Indeed, the beauty of procedural challenges comes from the fact that the testimony comes generally from
the police themselves, video, or documents such as the breath test instrument logbook.
Common Challenges to Breath Testing Science
Successfully Challenging breath test science typically requires
two things: First, the existence of some physiological or
physical condition which compromises the accuracy of breath testing; and Second the testimony of an expert witness -
typically a chemist, physicist, physician or other scientist qualified to testify in court that the physiological or physical
condition did affect the breath test. Expert witnesses typically charge a signifcant fee to compensate for their time
- Mouth Alcohol
One of the most prevalent causes of error in breath-alcohol analysis is the presence of alcohol in the mouth. This
alcohol can contaminate the expired breath captured by the breath testing instrument and elevate the results.
The accuracy of breath analysis is dependent on the assumption that the the subject is a normal, average and
healthy individual. The presence of diabetes can cause physiological symptoms that defy this assumption.
Diabetes can cause ketones on the breath to register in the breath test instrument as alcohol. In addition
acetone can be produced as a result of diabetes that can affect breath test results.
As discussed above successfully raising a science-based challenge to a breath test is almost certainly dependent
upon outside expert testimony. As you might imagine the costs associated with retaining expert scientific witnesses
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