California DUI

Alcohol Metabolism

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Once absorbed through the stomach/intestine walls, the alcohol passes into the portal vein that carries it to the liver, then to the right side of the heart, and then to the lungs. From the lungs (where the exhaled alveolar air is measured by breath analysis machines), the alcohol is carried in arterial blood to the left side of the heart and from there into the body's general circulatory system, by which means it eventually reaches the brain.

Blood-alcohol analysis in California DUI cases, then, is simply the attempt to measure the amount by weight of alcohol within the DUI suspect's blood at any given time. This amount, expressed as a percentage of the blood in which it is found, is then compared to a scale of percentages established by law for determining the presumptive levels of intoxication. The determination of the amount of alcohol in the blood can be accomplished directly by analyzing a sample of the subject's blood or indirectly by analyzing a sample of the subject's urine or breath.

The amount of alcohol found in the blood is the central issue in a California DUI per se charge. With the traditional DUI offense, however, it is only of secondary interest: It is the amount of alcohol actually absorbed into the brain that will affect an individual's ability to perceive, make judgments, and coordinate his movements - that is, his ability to operate a motor vehicle safely. But there is no practical means of measuring the alcohol absorbed by the body beyond that found in the bloodstream (or, even further removed, in the urine or the alveolar air). Because the bones, brain, fatty tissue, etc., contain a much lower percentage of water than does blood and because the alcohol level in blood is about 17 percent higher than that in the soft tissues, the concentration of alcohol in the entire body, including the brain, is always less than that in the blood. However, science has offered the "Widmark Factor R" - a designation of the ratio between the concentration of alcohol in the whole body divided by the concentration of alcohol in the blood. For men, this ratio averages about .67, with a range of .46 to .86; women usually have a somewhat lower ratio because of having a larger proportion of fatty tissue. Obviously, the fact that this ratio varies so widely according to the individual makes generalizations in any California DUI case very suspect.

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California DUI