Our client was charged with two counts of felony DWI. One count charged our client with driving under the influence of alcohol; the second count charged our client with having an alcohol concentration of .08 or more as measured within two hours of the time of driving.  Because of the client’s priors, the charges were both enhanced to felony level offenses.

The client was arrested shortly after 12:45 a.m., however, a sample of the client’s blood was not drawn until 3:23 a.m. Subsequent testing of the blood sample revealed an alcohol concentration of .092. The county attorney’s office requested a “retrograde extrapolation” be completed because the blood draw was outside the two hour-window from the time our client was driving. Stated simply, retrograde extrapolation is a process by which a forensic scientist attempts to determine what a person’s blood alcohol concentration may have been at the time of driving based on a number of variables. In our case, a forensic scientist from the Minneaota Bureau of Criminal Apprehension (BCA) applied a retrograde extrapolation to our client’s test result and concluded that our client’s blood alcohol concentration at the time of driving was .10 to .11.

Before trial, David successfully moved the district court to exclude evidence of retrograde extrapolation. The core basis for the exclusion of the evidence was that the BCA’s forensic scientist did not know a number of important variables necessary for conducting a valid retrograde extrapolation. The variables include such things as a person’s sex, height, weight, time of the person’s first drink, time of the person’s last drink, pattern of drinking, what kind of alcoholic beverages were consumed, and whether there is food in the stomach. The district court excluded the State’s retrograde extrapolation evidence, and dismissed the count charging our client with having an alcohol concentration of .08 or more as measured wtihin two hours of the time of driving. The case then proceeded to trial on the sole-remaining count of driving under the influence. If convicted, our client was looking at years of imprisonment.

Before trial, the district court judge ruled that the State could use the .092 blood test in its case-in-chief. This meant that the jury would be provided with evidence that our client’s blood alcohol concentration was .092 nearly three hours after the time of driving. The case was an uphill battle, but through relentless cross-examination of the arresting officer, a careful cross-examination of the BCA’s forensic scientist, and a persuasive showing by our own expert during the defense case, the jury returned a verdict of not guilty in less than two hours of deliberation. Our client walked out of the courthouse a free man thanks to David’s steadfast commitment to our client’s defense.