How to Challenge Breath Test Results at Trial – Part 1

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In a DUI prosecution for having a per se, or prohibited alcohol level offense, requires that the prosecution prove that the defendant had a prohibited concentration of alcohol at the time the person was operating a vehicle.  Alcohol tests are performed sometime after the defendant has been arrested for drunk driving.  By statute, the sample, whether blood, breath, or urine, must be obtained within 3 hours of the time the person is alleged to have operated the vehicle.

Test Does Not Reflect Alcohol Level

A defendant may challenge the weight of the evidence that a jury should give to an alcohol or breath test result by arguing that the test does not accurately reflect the person’s alcohol level at the time of the alleged offense because it was taken after the fact.  The earliest that a sample could be taken is generally within 20 minutes of the offense, and the latest is 3 hours.

Because the sample was obtained after the time of the alleged offense, it is unlikely that the later test result would be the same as the alcohol level at the time of the offense based on the body’s physiology.  While the results might be close, that doesn’t mean that they were the same.  This is particularly relevant when the test result is very close to the legal limit.  A skilled DUI lawyer will use this simple logic to create a reasonable doubt in the minds of the jury.

Test Does Not Reflect Amount of Alcohol Consumed

Another trial strategy for defending against an over the limit, or per se, DUI charge is to challenge the weight of the alcohol test result or the DUI breath test result based on the amount of alcohol the defendant actually consumed.  Essentially, the argument is that the alcohol test result is unreliably in light of the amount of alcohol actually consumed by the defendant.

This trial strategy requires several things.  The first is an expert witness.  The second is credible and accurate evidence of the timing, number, and nature of alcoholic beverages consumed, as well as other physiological factors.

While it is difficult for anyone, including an expert, to render an opinion as to the exact alcohol level for a given person, it is possible.  Furthermore, an expert can opine as to the amount of alcohol that would necessarily have to be consumed in order to have a test result consistent with that offered by the prosecution.  When that amount is compared to the amount of alcohol consumed by the defendant, as shown through other evidence, the state’s test result is put in question.  If the amount of alcohol necessary is extraordinarily high, the alcohol or breathing test result when compared with the evidence of actual alcohol consumption becomes suspect.

If you’ve been charged with a DUI offense in Columbus, Ohio, contact our skilled DUI Attorneys to help you defend your case.