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Alcohol Absorption

Blood alcohol content (BAC) is central to any DUI (Driving Under the Influence) or DWI (Driving While Intoxicated) case. Blood or breath alcohol levels can be the most damning - or exonerating - evidence against a motorist accused of driving under the influence. A chemical test result that exceeds the legal limit - .08 percent BAC in all 50 states - may seem particularly incriminating, but there are proven ways to challenge this evidence. A skilled California DUI defense lawyer can launch a challenge to chemical test results, and help a driver fight a drunk driving case.

One approach to contesting chemical testing is to question whether the test was accurate. However, even if the blood, breath or urine samples are accurate, the tests only reveals the motorist's alcohol level at the time of testing, not at the time of driving. It is the condition at the time of driving that is critical in DUI cases. There is typically a significant delay between the time of driving and the time of testing. The chemical test is relevant only to the extent that it allows a technician to look backward in time and estimate alcohol levels at the time of driving.

To understand how it is possible to challenge this evidence, it's useful to understand the process of alcohol absorption, distribution, and elimination in the human body. Because individual drivers differ so greatly in their metabolic rates, stomach contents, and drinking patterns, it is exceptionally difficult to look backward in time to pinpoint BAC at an earlier time. This difficulty increases with the passage of time, and becomes more and more speculative. Obviously, for the DUI criminal defense attorney whose skill lies in highlighting reasonable doubt as to any elements of the offense in a DUI case, this becomes increasingly valuable.

It takes time for alcohol to be absorbed into the body. When alcohol is ingested, it goes first into the stomach, then into the small intestine, which is where most absorption takes place. The type of alcohol consumed, as well as the stomach contents prior to and during drinking, will affect the speed at which absorption takes place.

Alcohol absorption begins immediately, so therefore the body cannot eliminate alcohol as quickly as it is absorbed. This is how alcohol levels begin to elevate in the human body. The process can be compared to a bathtub that has no stopper but a slow drain - as water flows into the tub, it drains at the same time, but because it flows in faster than it flows out, the level increases. Alcohol absorption in the human body works in roughly the same way.

After a person stops drinking, alcohol absorption continues. The person's alcohol level increases, followed by a peak or plateau. This peak level represents perfect equilibrium - absorption and elimination occur at the same rate, so the alcohol level flattens out and is consistent for a period of time - usually 15 to 45 minutes, depending upon metabolic rate and stomach contents.

When the peak or plateau period ends, the drinker enters the pure elimination phase. As long as no additional alcohol is consumed, the alcohol level steadily decreases at a rate of approximately .02 percent per hour. However, this rate can vary widely from person to person and in situation to situation.

When the process is shown as a graph, it resembles a bell curve. Even a chemical test above the legal limit doesn't accurately show what part of the curve the motorist was at the time of driving.

Breath testing can be especially inaccurate when performed during the absorptive phase (the first half of the bell curve). A wealth of scientific literature demonstrates that breath testing during the absorptive phase overestimates true alcohol levels by at least 40 percent, and by as much as 100 percent.

The rate at which a driver absorbs and eliminates alcohol depends greatly on an individual's metabolic rate, eating patterns, fatigue level, and many other factors. However, a police officer's roadside investigation is not thorough enough to effectively address these issues. This information is extremely valuable in the hands of a well-trained DUI defense lawyer, who can devastate the prosecution's DUI case by effective cross-examination on these issues.

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