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  • WisBar News
    September 02, 2014

    Post-Daubert: Testimony on Back Extrapolation of Alcohol Level Still Admissible

    Sept. 2, 2014 – Based on a “back extrapolation,” a toxicologist concluded that Todd Giese’s blood alcohol concentration was close to triple the legal limit when he crashed his car about four hours before the actual blood was drawn by a medical technician.

    In State v. Giese, 2013AP2009-CR (Aug. 27, 2014), a three-judge panel for the District II Court of Appeals ruled that expert opinion about back, or “retrograde” extrapolation was admissible despite Giese’s argument that it did not pass the Daubert standard.

    “We conclude that the expert’s opinion about retrograde extrapolation is admissible … because it was the product of reliable principles and methods and based upon sufficient facts and data, which is all that Daubert requires,” wrote Chief Judge Richard Brown.

    In July 2015, police in Washington County responded to a report that a man was lying in the roadway. Police found Giese in a very intoxicated state. He told police he crashed his car three hours earlier and began walking before falling asleep in the road.

    The crash scene was three miles away, and authorities testified that there were no bars or restaurants in between the crash site and the place where Giese passed out. In other words, police suggested that he probably did not have a drink after he crashed.

    Police took Giese to a hospital, where a medical technician drew his blood. The blood sample later revealed a 0.181 blood alcohol concentration. The legal limit is 0.08.

    He was later charged with operating while intoxicated (OWI), as a fifth or sixth offender, as well as prohibited alcohol concentration with an enhancer for high blood alcohol.

    The state requested a back extrapolation for evidence that Giese would have been driving with a much higher blood alcohol level at the time of the crash.

    In extrapolating the blood sample, the toxicologist assumed that all alcohol was fully absorbed before the accident and Giese did not ingest any alcohol after the crash.

    The toxicologist concluded that in the four to 4.5 hours prior to the actual blood sample, Giese had an estimated blood alcohol level of 0.221, almost triple the legal limit.

    Giese argued that the extrapolation results were inadmissible, because the blood sample was taken more than three hours after the crash.

    Thus, the state had to prove its probative value through expert testimony, and that could not be done because the extrapolation was based on questionable assumptions.

    Giese also challenged the scientific method employed by the toxicologist who performed the retrograde extrapolation. At a hearing, the state called the toxicologist as an expert witness and laid a foundation for her opinion testimony as an expert.

    Giese challenged the expert, citing the work of a well-known scientist who said valid extrapolation of blood alcohol concentrations is not possible on an individual analysis.

    The toxicologist admitted that time of alcohol ingestion and absorption are “critical elements” in the extrapolation analysis, and her findings were based on assumptions.

    Despite Giese’s efforts, the trial court ruled that the toxicologist’s opinion about the back extrapolation was admissible. The court said the results were based on sufficient data and facts, partly because it was not probable that Giese ingested alcohol after crashing.

    The appeals court affirmed. It said the toxicologists’ testimony met the Daubert standard for reliability. “The standard is flexible but has teeth,” Judge Brown wrote. “The goal is to prevent the jury from hearing conjecture dressed up in the guise of expert opinion.”

    The appeals court noted that the Daubert standard, codified in Wisconsin law in 2011, asks whether the principles and methods that an expert relies upon to make conclusions have a reliable foundation in that field of scientific study.

    “The willingness of courts to allow testimony about retrograde extrapolation makes sense given the record in Giese’s case, which shows that despite certain doubts and disagreements, retrograde extrapolation is a widely accepted methodology in the forensic toxicology field,” Judge Brown wrote for the three-judge panel.

    “The mere fact that some experts may disagree about the reliability of retrograde extrapolation does not mean that testimony about retrograde extrapolation violates the Daubert standard,” Judge Brown wrote.

    The appeals court noted that a jury could choose to give more or less weight to the toxicologist’s testimony, based on the assumptions, but it is still admissible.

    “Giese still has the chance to undermine the assumptions that support the expert’s opinion by introducing evidence or arguing in favor of competing inferences from the known facts,” Brown wrote. “But the expert’s opinion is admissible under Daubert.”

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