California DUI

Alcohol Metabolism

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In organs having a rich blood supply, such as the kidneys, brain, and liver, the tissues very quickly attain alcohol equilibrium with the arterial blood. Voluntary muscle tissue, however, has a much smaller blood flow per unit of weight and as a result requires longer to reach alcohol equilibrium after ingestion. Since the muscles make up about 40 percent of body weight, this delay in alcohol absorption by the muscles results in high concentrations of alcohol in arterial blood and in the brain during active absorption of alcohol. The result is the common phenomenon that an individual may appear greatly affected only a few minutes after taking two or three drinks, and then rapidly sober up within 15 to 30 minutes in apparent contradiction to normal expectations. This, of course, can raise serious doubts about the relevance of blood-alcohol tests.

Many factors in a DUI case can affect the rate of absorption and distribution of alcohol into the system and, ultimately, into the brain. The most common is that different individuals have different rates and these rates can vary within a given individual. External factors also can cause variation. The effects of cold weather or extreme stress, for example, can cause less blood to be delivered to the muscles and more to the brain; with more blood being delivered to the brain, more alcohol is also delivered, thus raising the blood-alcohol level. Ritchie, The Aliphatic Alcohols, in Goodman and Gilman's The Pharmacological Basis of Therapeutics (7th ed. 1985). Therefore, it would appear that the stress caused by a DUI stop and investigation -- interrogation, field sobriety tests and arrest -- could themselves cause higher blood-alcohol levels when the DUI arrestee is later tested at the police station.

Absorption and actual concentration are only two aspects of blood-alcohol analysis in a California DUI case. Elimination, or the rate of disappearance of alcohol from the body, is of equal importance. The body reduces the amount of alcohol by oxidation in the liver. The rate of this elimination is, once again, a matter that varies from one person's physiology to another's, but it appears probably to be independent of concentration. The rate of disappearance, called the "Widmark Factor B," is generally about .015 percent per hour - that is, the body will "burn off"' about .015 percent alcohol in the blood in an hour. If a DUI suspect has a reading of .08, for example, he should have a reading an hour later (assuming, of course, no further consumption of alcohol) of about .065. Put another way, an individual will eliminate approximately 1/2 to 2/3 of an ounce of 100 proof whiskey in an hour. This rate of disappearance can vary from .010 percent to .020 percent per hour, although dissipation of as high as .06 percent has been scientifically observed. Again, the wide variation in individual rates of disappearance gives the lie to attempts to test all DUI suspects on the theory of uniform burn-off rates.

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California DUI