Missouri DUI license case - metabolic curve testimony
In a Missouri DUI license suspension case, the Missouri Court of Appeals upheld the admissibility of evidence concerning the metabolic curve of the driver. This scientific principal goes by a variety of different names, the most common of which is probably “retrograde extrapolation.” The idea is to predict an alcohol level at a point other than that at which the blood or breath test was taken.
The Cite: Krieger v. Director of Revenue, --- S.W.3d ----, 2008 WL 4200774, Mo.App. W.D.,2008. September 16, 2008
Relevant excerpts from the opinion:
In his sole point on appeal, the Director asserts that Krieger did not rebut his prima facie case. In particular, the Director contends that the circuit court erred in admitting the results of Martinez's calculation of Krieger's blood alcohol content based upon the “metabolic curve.”
Martinez based his “metabolic curve” calculation upon information that Krieger stopped drinking only five to ten minutes before she was stopped by the police.
Analysis: Most DUI defendants are under the mistaken impression that drinking a lot right before the stop hurts their case. Especially in breath test cases, the opposite is often true. The closer in time the last drink to the application of a breath test, the more likely it is that the person was still in the absorptive phase of alcohol metabolism. In the absorptive phase, studies show that a person’s average partition ratio is lower than the 2100:1 that all breath test devices are programmed to expect. Therefore, as long as the DUI defense lawyer is allowed to present this evidence, drinking close to the time of the stop is helpful in breath test cases.
The trend amongst states is to legislate out the defense’s ability to present retrograde testimony. The most common way of doing so is to make any alcohol level above the legal limit within 2 hour of driving per se illegal. In an extreme example, a person could chug a pint of vodka, immediately get into the car, and immediately get pulled over leaving the bar parking lot two minutes later. At the time of driving the person could be under the legal limit of .08. An hour later that same person, having consumed no additional alcohol, could be above a .20.
Aside – DUI cases are not about fairness: It hardly seems fair to prosecute a person from “drunk driving” when they weren’t drunk or impaired while behind the wheel. The short answer is that the law doesn’t care about the reality of impairment, only what fits into the purview of the statute under which prosecution is pursued. All DUI lawyers know this already, but for my non-attorney readers and the young ones who are still under the illusion of fairness, this aside is for you.
