Wednesday , October 18 2017
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The Unseen Risks of “One for the Road”

One evening at a restaurant, Martha shares a bottle of wine with a friend.  She nurses one glass over a one-hour dinner.  Nearing the end, another glass is poured from the bottle and she finishes this.  The two friends then order an after-dinner drink.  Noting the time, Martha quickly finishes the drink and leaves.  She is stopped by the police one block from the restaurant.  After questioning and field sobriety tests, she is taken to a police station and tested on a breathalyzer.  The machine shows her blood alcohol concentration (BAC) to be .09% — over the legal limit.  She is booked for DUI and jailed.

Martha’s true BAC, however, was much lower.  If a blood sample had been taken instead of a breath test, the results would have shown only .05% — well under the legal limit for DUI.

One of the most common sources of error in breath alcohol analysis is simply testing the subject too early — while his or her body is still absorbing the alcohol.  Absorption of alcohol continues for anywhere from 45 minutes to two hours after drinking or even longer.  Peak absorption normally occurs within an hour; this can range from as little as 15 minutes to as much as two-and-a-half hours.  The presence of food in the stomach can delay this to as much as four hours, with two hours being common.

During this absorptive phase, the distribution of alcohol throughout the body is not uniform; uniformity of distribution — called equilibrium – will not occur until absoprtion is complete.  In other words, some parts of the body will have a higher blood alcohol concentration (BAC) than others.  One aspect of this non-uniformity is that the BAC in arterial blood will be higher than in veinous blood (laws generally require blood samples to be veinous).  During peak absorption, arterial BAC can be as much as 60 percent higher than veinous.

This becomes very relevant in DUI cases because the alveolar sacs in the lungs are bathed by arterial blood, not veinous:  The diffusion of alcohol through the sacs and into the lung air will reflect the BAC of the body’s arterial blood.  Therefore, the breath sample obtained by the machine will be reflective of pulmonary BAC — which, during absorption, will be considerably higher than veinous BAC (and higher than the BAC in other parts of the body).

After extensive research, one of the most noted experts in the field of blood alcohol analysis has concluded:

Breath testing is not a reliable means of estimating a subject’s blood alcohol concentration during absorption…..

There is a significant likelihood that a given subject will be in the absorptive state when tested under field conditons.  Because of large differences in arterial BAC and veinous BAC during absorption, breath test results consistently overestimate the result that would be obtained from a blood test — by as much as 100% or more.  In order to have some idea of the reliability of a given breath test result, it is essential to determine by some objective means whether the subject is in the absorptive or post-absorptive state.  In the absence of such information, an appropriate value for the uncertainty associated with the absorptive state should be applied to all breath test results.  Simpson, “Accuracy and Precision of Breath Alcohol Measurements for Subjects in the Absorptive State”, 33(6) Clinical Chemistry 753 (1987).

The most recognized expert in the field, Professor Kurt Dubowski of the University of Oklahoma, agrees with Simpson: “When a blood test is allowed, an administered breath test is discriminatory, because in law enforcement practice the status of absorption is always uncertain.”

So you might want to pass on that next “one for the road”….

 

About Lawrence Taylor

Lawrence Taylor
Lawrence Taylor is one of the most respected DUI defense attorneys in the country. With over 43 years experience in DUI defense, he has lectured to attorneys at over 200 seminars in 41 states. An original founder and former Dean of the National College for DUI Defense, Mr. Taylor's book "Drunk Driving Defense" has been the best-selling textbook on the subject for 31 years and is now in its 7th edition. He is today one of only 5 DUI attorneys in California who is Board-certified as a DUI defense specialist. A former Marine and graduate of the University of California at Berkeley (1966) and the UCLA School of Law (1969), Lawrence Eric Taylor served as deputy public defender and deputy district attorney in Los Angeles before entering private practice. He was the trial judge's legal advisor in People vs Charles Manson, was Supreme Court counsel in the Onion Field murder case and was retained by the Attorney General of Montana as an independent Special Prosecutor to conduct a one-year grand jury probe of governmental corruption. Turning to teaching, Mr. Taylor served on the faculty of Gonzaga University School of Law, where he was voted Professor of the Year, was invited to be Visiting Professor at Pepperdine University Law School, and was finally appointed Fulbright Professor of Law at Osaka University in Japan. Mr. Taylor continues to limit the practice of his 5-attorney Southern California law firm to DUI defense exclusively. With offices in Long Beach, Irvine, Beverly Hills, Pasadena, Riverside and Carlsbad, Mr. Taylor and his firm of DUI defense attorneys may be reached through their website at www.duicentral.com or by telephone at (800) 777-3349.

If you would like to contact the author, please visit: http://www.duicentral.com/


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