Mississippi’s Use of the Intoxilyzer 8000 Breath Test and Driving Under the Influence (DUI)

Practicing DUI law, we receive all kinds of questions regarding the evidence that could potentially be used against someone in a court of law. Many people’s questions tend to focus on the accuracy and the vulnerabilities of the Intoxilyzer 8000- the device used in Mississippi to read blood alcohol content (BAC). The Intoxilyzer 8000 is not to be confused with the portable breath test given roadside. Instead, this $8,000.00 machine is typically used once someone arrives at the station, and the accuracy, or inaccuracy, of this machine could greatly influence the outcome of a DUI case. The Intoxilyzer 8000 is not used in every state, and has come under serious scrutiny in Ohio and Florida for insufficient accuracy. Many people believe such devices to be infallible, and this misplaced belief could lead to much too great a weight being placed on the readings.

To better understand the breath test, it is important to first understand what processes are underway. The indigestible alcohol we drink is known as ethyl alcohol or ethanol, which is a central nervous system depressant, meaning it does not affect a person until it has entered the central nervous system through the blood (the brain, brain stem, and spinal cord). In order to get into the blood from the stomach, alcohol must undergo the process of absorption, which can be influenced by various factors. Perhaps the greatest influence on absorption is the presence of food contents in the stomach, and drinking on an empty stomach can lead to extremely rapid absorption rates. In fact, studies have shown that the absorptive stage can last anywhere from 12-166 minutes. Since most drivers take a breath test within 120 minutes of their last drink, their actual BAC will likely be overestimated by a breath test.
Once the alcohol moves from the stomach into the blood, it will be distributed throughout the body. Alcohol has an affinity for water, and the blood will carry the alcohol to the various tissues and organs of the body, depositing the alcohol in them in proportion to their water content. Our brains have a high water content, so the brain tissue receives a substantial share of the distributed alcohol. Also of note, the typical female’s body contains much less water than the typical male’s. A Swedish alcohol researcher determined that the typical male body is about 68% water, while the typical female body is only about 55%. This note is important, because if a woman and a man who weighed exactly the same drank exactly the same amount of alcohol, her BAC would climb significantly higher than his.

As soon as alcohol enters the body, the body system starts trying to get rid of it. Some of the alcohol will be directly expelled from the body chemically unchanged. For example, some alcohol will leave the body in the breath, in the urine, in sweat, and in tears. However, only about 2-10% will be directly eliminated. Most of the alcohol a person drinks is eliminated by metabolism in the liver through an enzyme known as alcohol dehydrogenase. On average, a person’s BAC will drop by about 0.015% per hour. Put differently, if someone drank to the BAC equivalent of 0.08%, it would take 6 hours to return to a BAC of 0.00%.

A person with a BAC greater than 0.08% is considered impaired for the purposes of driving under the influence. The Intoxilyzer 8000 only requires a precision of two readings within 0.02% of one another, which means for a reading of 0.08%, an acceptable error is 25% of the total! Reports have also begun surfacing that call into question the programming of the software, which can at times provide a BAC with a report that no air was blown into the machine (0.0L) or, conversely, provide a BAC with a report under the required (1.1L) without providing the programmed “volume not met” warning.

Breath testing further presumes that all people have an expired breath temperature of 34 degrees C, and for each degree above this number, the results will register higher than normal. Someone suffering from fever or hot flashes will record an inappropriately high BAC reading on a breath test. Along with expired breath temperature, the Intoxilyzer 8000 and similar breath tests can provide incorrect readings for various other factors, including the above mentioned alcohol absorption rates, residual mouth alcohol, low-carb diets, diabetic reactions, radio interference, acid reflux, regurgitation or burping, and dentures, to name a few.

As you can see, the Intoxilyzer 8000 and similar breath tests are complex and rely on various factors for their reliability. Many jurisdictions are beginning to call into doubt the precision of such machines, and no one should accept the results as conclusory.

If you have been charged with driving under the influence, or have further questions about anything discussed above, do not hesitate to contact us at 662-234-8775.

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Jonathan Masters

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