California DUI defense lawyer Lawrence Taylor cites several fascinating studies in his DUI blog suggesting that how you breathe can dramatically impact the blood alcohol reading generated by a breath test. For example, holding your breath for 30 seconds increased the blood alcohol content of your breath by over 15%. Hyperventilating for 20 seconds decreased the BAC by 10%.
In his post about breathing and breath tests, Attorney Taylor also cites a research study by a University of Washington Professor of Physiology who found that the last part of your exhalation has a higher alcoholic content than the first part, meaning that a police officer’s command to “blow harder” may very well result in a higher BAC reading on the breath test.
Georgia Courts have long rules that arrest scene breath tests are not admissable evidence. Mr. Taylor explains the science behind the reasons breath tests are flawed in another post on his blog. It would be interesting to know the psychological impact that a failed breath test has on a defendant’s subsequent decisions to admit to alcoholic consumption or to not assert his other available rights.