Breath Testing While Absorbing Alcohol Causes False Readings

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Alcohol’s Path Through the Human Body

After you drink alcohol, it enters your stomach and then your small intestine, where it enters your bloodstream and affects your brain and central nervous system. Your ability to drive is not affected by the alcohol your body has not yet absorbed.

Because alcohol is absorbed, distributed, metabolized, and eliminated over time, the police officer asked you questions about your alcohol consumption. These questions are typically about what you were drinking, how much, when you started and stopped drinking, and where you were drinking. They may also have asked about your last meal and what you ate.

The Alcohol Curve

This alcohol curve shows how your blood alcohol concentration (BAC) (increases) rises toward a peak, and then falls (decreases). The amount of alcohol in your body is measured by the weight of the alcohol in a certain volume of blood. This is called the blood alcohol concentration (BAC). BAC is expressed as either 0.08 grams of alcohol per 100 milliliters of blood or 0.08 grams of alcohol per 210 liters of breath. VC 23152b.

Absorptive Phase

The absorptive phase of the alcohol curve is when your BAC starts to rise. During the absorptive phase, there are differences between the alcohol concentrations in arterial blood, venous blood, and breath. During absorption, arterial blood has a higher concentration of alcohol than venous blood. The lungs have a higher alcohol concentration than the brain. The brain is the location where alcohol affects your ability to drive safely.

There is debate over how long this phase lasts, but the prosecution typically argues that absorption is completed almost immediately after you finish your last drink. However, according to one of the leading scholars on the subject, Dr. Kurt Dubowski, “it is often impossible to determine whether the postabsorptive state has been reached at any given time,” Absorption, Distribution, and Elimination of Alcohol: Highway Safety Aspects, Journal of Studies on Alcohol, Supp. 16, July 1985, p. 105.

There are many factors that affect how quickly alcohol is absorbed into the blood, such as the type and amount of food in the stomach, whether the person has any GI diseases, and whether they have taken any other drugs (such as aspirin). These facts are often ignored by the prosecution. When any of the factors are present, absorption can be delayed by 2 to 6 hours. See, Goldfrank’s Toxicologic Emergencies, Ninth Ed., Lewis M. Nelson, MD, et al.

Elimination Phase

The elimination phase of the alcohol curve is on the right-hand side, showing your BAC decreasing over time. After you reach your peak BAC, your body begins to flush the alcohol from your system. Elimination rates generally differ from person to person but are typically between .015 and .020 percent per hour. This is in contrast to unpredictable absorption rates, which vary widely.

However, AW Jones, another renowned academic, warns in a peer-reviewed article that attempting to “measure the elimination rate from two randomly timed tests is seriously flawed.” Physiological variations in blood ethanol measurements during the post-absorptive state, Journal of the Forensic Science Society, 1990; 30: p. 280.

Just like there are factors that affect absorption, many things affect the rate of elimination, such as: how much you drank, your drinking pattern, and whether you had anything to eat while you were drinking.


            DataMaster DMT Breath Testing Machine


As your body is absorbing the alcohol into your bloodstream, the alcohol is unevenly distributed throughout your body – it is not in equilibrium. If you are given a breath test while you are absorbing, the test will likely result in a high reading that is not accurate. Imagine if you dumped a jug of chlorine into one end of the swimming pool. Without waiting for the chlorine to circulate evenly throughout the water, you took a sample of the water to measure for chlorine. If you took a sample of the water at the end of the pool where you just poured it, you would get a falsely high reading.

Keep in mind, this happens even if the breathalyzer is perfectly calibrated and the person giving you the test followed all the right steps. The breath machine is unable to tell the difference. One of the leading experts in the field has documented the problem with breath testing during absorption:

“… results from data in the literature indicate that breath testing is not a reliable means of estimating a subject’s BAC during absorption. The results also indicate that there is a significant likelihood that a given subject will be in the absorptive state when tested under field conditions. …breath test results consistently overestimate the result that would be obtained from a blood test by as much as 100% or more. G. Simpson, Accuracy and Precision of Breath Alcohol Measurements for Subjects in the Absorptive State, CLINICAL CHEMISTRY, Vol.33, No.6, 1987, p. 756.

There may be other flaws in the evidence in your DUI case, this is just one of them. If you have been arrested for a DUI and took a breath test, contact The Law Office of Richard Wagner at 714.721.4423.


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