Articles Tagged with OVI defense

How to improve litigation skills which lead to more acquittals (not guilty verdicts) in DUI/OVI cases can be a mystery. That’s why there are organizations like the National College for DUI Defense (NCDD) and the National Association of Criminal Defense Lawyers (NACDL). Those organizations co-host an annual DUI defense seminar in Las Vegas, and the theme of this year’s seminar was “Solving The Mystery of DUI Acquittals”. I attended the seminar, as I have for over 15 years, and took away valuable insights.


Day One: Retrograde Extrapolation & Cross Examination
On the first day of the seminar, there were two presentations which stood out to me. The first was Joseph St. Louis’ discussion of retrograde extrapolation. St. Louis is a DUI lawyer in Tuscon and a regent for the NCDD. After teaching how alcohol is absorbed, distributed and eliminated, he explained retrograde extrapolation. Retrograde extrapolation is the act of calculating a person’s blood alcohol concentration (BAC) at a previous time based on the BAC at a later time. St. Louis highlighted articles from scientific journals concluding retrograde extrapolation is a dubious practice due to all of the possible variables in the calculation, most of which are unknown to the person completing the calculation.

Retrograde extrapolation is important in Ohio because our OVI law prohibits operating a vehicle if, at the time of operation, the driver is under the influence or ‘over the limit’. In an OVI trial, the prosecution introduces the result of a blood/breath/urine test, and that test may be done up to three hours after operation of the vehicle. That test result is circumstantial evidence of the BAC at the time the defendant operated the vehicle. However, an expert witness can testify the BAC at the time of operation cannot be calculated with certainty: there is, in fact, a wide range of possible BACs, including BACs ‘under the limit’.

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