State v. Trujillo

Expert testimony that "retrograde extrapolation" is a practice that is accepted in the field of forensic science is sufficient to admit evidence of "retrograde extrapolation" in DUII cases.

Defendant appealed conviction for driving under the influence of intoxicants (DUII) and reckless driving. In the appeal Defendant made three assignments of error, the third of which questioned the admission of expert testimony concerning “retrograde extrapolation” (backwards calculation of an individual’s blood-alcohol content (BAC)) to determine Defendant’s BAC at an earlier time. Defendant argued that “retrograde extrapolation” as a concept is not scientifically reliable and therefore should not have been admissible, and even if the evidence is considered admissible, that the state did not lay a proper foundation to use the evidence. At the evidentiary hearing, an expert testified that in order to perform “retrograde extrapolation,” a range of BAC must be given in order to decrease error. Expert also testified that retrograde extrapolation is accepted in forensic science. The Oregon Court of Appeals applied several factors of analysis to determine the legitimacy of the evidence of “retrograde extrapolation,” including the acceptance of the method in forensic science, the expert’s qualifications, the use of the method, the rate of error, and the novelty of the method. The Court found that the expert had proper credentials. Based on the testimony of the expert witness at the evidentiary hearing, “retrograde extrapolation” is accepted in the forensic science community as a legitimate test of previous BAC levels, and therefore found that the trial court did not err when it found that the expert’s testimony on “retrograde extrapolation” was admissible. Judgment AFFIRMED.