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OWI — foundation for expert testimony regarding BAC at time of driving

City of Port Washington v. David A. Thompson, 2012AP2500, District 2, 6/26/13; court of appeals opinion (1-judge; ineligible for publication); case activity

The trial court did not err in allowing Hackworthy, the state’s chemical test expert, to give her opinion that Thompson’s BAC at the time of driving was 0.15 based on average alcohol elimination rates and the results of a blood test taken about an hour after driving (with a result of 0.15) and a breath test taken about two hours after driving (with a result of 0.11). The court rejects Thompson’s argument that the expert’s testimony lacked foundation because she did not know whether he was absorbing or eliminating alcohol when his blood sample was taken:

¶8        …. The record shows that Hackworthy disclosed the methodology and explained how her calculations could be inaccurate. She explained in detail the process of alcohol absorption and elimination, and why she applied an average range. Defense counsel was able to cross-examine her on the assumptions upon which her calculations were based. While Thompson complains that Hackworthy failed to make a “connection between Mr. Thompson’s testimony regarding his consumption and his level of absorption,” the record indicates that Hackworthy’s calculations took into account Thompson’s repeated denial to the arresting officer that he had anything to drink. See Wis. Stat. § 907.03 (expert may base opinion on facts made known at or before hearing). While Thompson then testified at trial that he drank six beers, defense counsel was free to explore the effect this change in testimony would have on Hackworthy’s assumptions and calculations. The jury was able to weigh the evidence and decide for itself whether to agree with Hackworthy’s calculation. It was reasonable for the circuit court to conclude the testimony would assist the jury in its determination of whether Thompson’s BAC was above .15.

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