A blood test, especially if it’s high, makes the prosecutor’s job much easier.  Even skeptics who mistrust breath testing will typically be satisfied if there is a blood test.  Just because a lawyer handles DWI cases does NOT mean he or she understands blood testing. Defense lawyers have to be especially skilled to even understand the blood testing process.  Even if a lawyer does understand it, it takes much more than that to win a blood test case at trial.  Our record defending blood test cases is especially successful, so you can be sure we know what we’re doing.

Breath testing is fertile with potential errors and assumptions that can be exploited.  Blood testing, by contrast, has relatively few weak links.  This calls for much greater skill from the lawyer.  With more and more DWI cases involving blood, you have to be extra careful about who you hire.  Have they ever taken a blood test to jury trial, much less won one?  How many high test cases have they gotten dismissed?  These are questions you MUST get answers to before you hire any lawyer to handle a blood test DWI.  I can’t tell you how many times other DWI lawyers ask us to teach them how to handle their own client’s DWI blood test case.  Be careful who you hire on these!

How Blood Tests Work

The following excerpt from Drunk Driving Defense, 6th Ed., by Lawrence Taylor, J.D. and Steven Oberman, J.D. gives a general overview of the blood testing process and sets out some basic methods of challenging it in court:

Ethanol, or ethyl alcohol (grain alcohol), is a clear fluid whose low molecular weight and high solubility in water cause it to diffuse rapidly through body tissue membranes and reach equilibrium in tissues at levels proportional to water content. Blood, for example, will hold proportionately more alcohol than will muscle tissue.

The concentration of alcohol in an individual’s body depends on the amount of water contained in that body. The more water present in the body, the more diluted the alcohol will become as it is absorbed into the system. And the simple fact is that individuals vary according to the percentage of water in their bodies.

In a study entitled “Pharmacokinetics of Ethanol in Plasma and Whole Blood: Estimation of Total Body Water by the Dilution Principle,” researchers confirmed that the body’s water content varies from person to person. The content in men, interestingly, decreases with age—that is, the blood-alcohol concentration will become higher. Further, when an individual has experienced trauma, as in an automobile accident, the body’s percentage of water will decrease. The same can also happen due to pathological conditions, as in persons with diarrhea, heart failure, or impaired renal function.

For alcohol to produce its effect, it must reach the brain. To accomplish this, it first passes into the bloodstream after absorption through the walls of the stomach and small intestines. This is a simple biochemical process of diffusion, which will continue as long as the concentration of alcohol in the stomach and intestines is higher than that in the blood.

In contrast to ordinary foods and many drugs, alcohol is absorbed rapidly from the stomach and even more rapidly form the small intestine just beyond the stomach. In fact, the presence of alcohol is initially detectable about five minutes after consumption, and its maximum concentration within the body tissues is achieved in 30 to 90 minutes. This rate of absorption can be accelerated if the subject has ingested significant amounts of water or materials containing water, and it can be slowed down if he has eaten food. The type of alcoholic beverage can also be a factor: Beer will cause a slower increase in blood-alcohol concentration than will distilled spirits, as well as a lower peak level and faster decline. Absorption is complete when the entire gastrointestinal tract reaches equilibrium with the remainder of the body; this can take as long as two-and-a-half hours, but commonly occurs within 30 to 90 minutes. In any event, the rate of absorption of alcohol—and, as a result, the effect on the nervous system– varies according to the individual.

Once absorbed through the stomach and 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, then, is simply the attempt to measure the amount by weight of alcohol within the subject’s blood at any given time. This amount, expressed as a percentage of the blood in which it is found, is then compare to a scale of percentage 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 per se charge. With a traditional DWI charge, 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 ration 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 they have a higher proportion of fatty tissue. Obviously, the fact that this ratio varies so widely according to the individual makes generalizations about a given individual very suspect.

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 sobers 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 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. Therefore, it would appear that the stress caused by, say, field sobriety tests, arrest, and booking could themselves cause higher blood-alcohol levels when the individual is later tested at the police station.

Absorption and actual concentration are only two aspects of blood-alcohol theory, 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 an individual 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, and individual will eliminate approximately one- half  to two-thirds 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 elimination gives the lie to attempts to test all drunk driving suspects on the theory of uniform burnoff rates.

How does all this translate into everyday experience? An average person of 150 to 170 pounds probably must consume, on an empty stomach, approximately 8 to 10 ounces of 100 proof whiskey (eight to ten beers, or four to five highballs) to reach a blood-alcohol level of .15 percent; this is equal to 15 parts of alcohol per 10,000 parts of blood in the subject’s system by weight, or about 2 parts of alcohol by volume for ever 1,000 parts of blood. But, again, the ever-present aspect of individuality can confound scientific premises. A heavy drinker, because of his altered physiology or biochemical reactions, may have to drink 12 ounces of 100 proof whiskey before that same level of .15 percent is reached. And a level of .15 percent can have wildly different effects on the nervous systems of different individuals and hence on their ability to operate motor vehicles safely.

Potential Problems With Blood-Alcohol Tests

All of this is, of course, theoretical. The one simple overriding fact that continues to frustrate attempts to measure blood-alcohol concentration is the incredible variability between one individual and another—and, within a single individual, from one moment to the next.
Dr. Kurt Dubowski, probably the most recognized expert in the field of blood-alcohol analysis, has succinctly summarized some of the problems with DWI blood-alcohol tests in an article entitled “Absorption, Distribution and Elimination of Alcohol”:

First, not all blood and breath alcohol curves follow the Widmark pattern, nor is the elimination phase linear. Second, alcohol absorption is not always complete within 60 to 90 minutes as often claimed. Third, the peak alcohol concentration cannot be validly predicted or established in an individual instance without frequent and timely measurement of alcohol concentrations. Fourth, it is not possible to establish whether an individual is in the absorption or elimination phase, or to establish the mean overall rate of alcohol elimination from the blood or breath, from the results of two consecutive blood or breath, from the results of two consecutive blood or breath alcohol measurements, however timed. Fifth, significantly large short-term fluctuations occur in some subjects and result in marked positive and negative departures form the alcohol concentration trend line. Sixth, short-term marked oscillation of the blood or breath alcohol concentration can occur at various points on the curve, resulting in repeated excursions of the alcohol concentration above and below a given concentration within a few minutes or for hours. Finally, no forensically valid forward or backward extrapolation of blood or breath alcohol concentrations is ordinarily possible in a given subject and occasion solely on the basis of time and individual analysis results.