How Does Timing of the DUI Chemical Test Impact a Case? - DUI Attorney
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How Does Timing of the DUI Chemical Test Impact a Case?

 Timing of the DUI Chemical Test

In each DUI case a sequence of events will occur from the time you are initially stopped (or found) until the time you are eventually arrested and then processed. The timing and order of these events will depend upon the circumstances of your case.

Some DUI investigations take just a few minutes, while others take hours.

Several factors could prolong your DUI investigation. These factors include:

The longer your investigation takes, the more time there will be between your driving and the chemical test of your blood, breath, or urine.

Does is really matter when you take the DUI chemical test?

The answer is yes. It does matter and can have a significant impact on the result of the alcohol test, and therefore your case.

Without getting into the detailed science of how our bodies digest and break down alcohol, let’s start with the basic truism that each person feels affects of alcohol differently and at different times. Each absorbs and eliminates alcohol at a unique rate.

The amount and type of alcohol you consumed, whether and when you last had a meal, what medications you are taking, your height, weight, age, gender, health history, etc. are all relevant factors.

Many people mistakenly believe they will pass a breath test if a few hours have passed since their last drink. This may or may not be the case, depending on where you are in the alcohol curve. It takes some people up to four hours to fully absorbe their alcohol before they even start exclusively eliminating alcohol from their system.

Why does timing of the chemical test matter from a legal standpoint?

In the past, prosecutors were required to prove beyond a reasonable doubt that your blood alcohol content (BAC) was above the legal limit, and that it was so at the time you were driving.

One way to prove BAC is to use the results of your breath, blood, and/or urine sample. But because these samples are always collected at some point after you have already been pulled over (sometimes hours later), all they really show is what your BAC level was at the time you took the test, not when you were actually driving.

Thus prosecutors had to prove their case with complex math – using your chemical test result and “retrograde extrapolation,” a term that really just means estimating backwards to determine BAC at time of driving. Though in most states the prosecution is no longer required to prove retrograde extrapolation, some states will allow defense attorneys to refer to it to help prove your innocence. The best DUI lawyers use mathematics and scientific principles to attack the validity, accuracy and admissibility of your result.

While each state is different, today every state does still require its prosecutors to meet a minimum level of criteria for the admissibility of chemical tests, including strict adherence to any time constraints. Some states require a set maximum time in which a chemical test can be offered to you, such as within two or three hours of your stop.

Others states determine admissibility on a case by case basis depending on the circumstances and the reasonableness of the testing. The longer it is between stop and test, the more unreasonable and unreliable the results will be. Be sure to check your local laws to determine your jurisdiction’s time limit.

Failure of the police to follow the time procedures may be challengeable in court. Note, however, that even if your test was given outside the allotted time period, it does not necessarily mean your result will be not be admitted into evidence against you. Contact an experienced DUI attorney in your state for more information.

Observation or deprivation periods in DUI breath test cases.

Not only are there time limits on when a chemical test may be administered after your stop, but there are also limits on how the test is to be conducted. If you submitted to a breath test, then more than likely you were taken into a special room where the breath machine (called the “intoxilizer,” “datamaster” “breatthalyzer”) is located.

What you probably did not notice, however, is that prior to taking the test, while or before you are taken into the room, a certain amount of time passed. This is because the police are required to observe you for a certain period of time (typically 15 to 20 minutes, depending on the state) before collecting your breath sample. At least one officer must be watching you at all times for the entire duration of the observation period.

The observation or deprivation period is required to ensure that vomiting, smoking, and consumption of food or beverage did not occur prior to testing. Such consumption could skew your results.

During this time you should not have been allowed to put anything in your mouth, including gum, candy, or other foreign objects. The time the observation began will be noted (typically on your breath card or in the police report). Double-check the times on your reports, and be sure to point out any discrepancies or unusual circumstances that may have occurred to your DUI attorney.

Observation period duration

In addition to the observation period, some states have limits on the duration of the test itself. Remember that prosecutors have the burden of proving you were DUI, and do so using your chemical test results. For a chemical test to be admissible, it must be shown to be somewhat reliable.

Depending on where you are, you may have been asked to blow into the breath machine more than once. States that admit more than one sample require that the results of each sample be within a certain time or each other, and for the results to agree within a certain percentage or decimal range of each other. The validity and reliability of your results can then be bolstered or negated by comparing the two breathalyzer results.

Failure of the breath test operator to follow the time limits may help your DUI defense. Again, however, please note that such an error will not necessarily render your results inadmissible against you. As some states only require one sample, be sure to check the local laws of your jurisdiction and consult an experienced attorney for more information.

To find out what factor the timing of your chemical test plays in your drunk driving prosecution, select the state of your arrest from the menu below and contact a qualified DUI attorney in your area to discuss your case.

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