Saturday, June 18, 2011

DUII Appeal - Oregon Allows Retrograde Extrapolation of Blood Alcohol to Prove Per Se

This case comes to DAD thanks to the watchful eyes of NCDD member Bruce Tarbox. In State of Oregon v. Eumana-Moranchel, the defendant filed a motion to exclude certain blood alcohol evidence, which was granted. The State then appealed. The defendant had blown 0.06 on the breath test. Shane Bessett, an expert in the field of alcohol absorption and dissipation, testified about the rate at which the human body absorbs and dissipates alcohol and the factors that influence absorption and dissipation. As part of that testimony, he explained Widmark's formula, a generally accepted method for calculating the rate of alcohol absorption and dissipation, and back extrapolation of BAC, a method to provide a range for a person's BAC prior to the time of the test. According to Bessett, Widmark's formula, the subject of many peer-reviewed studies and scholarly works, is used to determine the number of drinks consumed to reach a given BAC, and back extrapolation is used with Widmark's formula in instances of "any type of delay of time between time of test and time of driving." Back extrapolation of BAC relies on knowledge of a person's BAC at the time of a chemical test of the person's breath or blood.

The trial court entered an order excluding

"(1) Any testimony by state's expert witness referring to BAC content if that testimony would permit the jury to convict defendant based on his BAC.

"(2) Any testimony by state's expert witness that [defendant's] BAC at the time of the alleged stop was at least .08 percent."

On appeal, the appellate court reversed. First, they found that the expert could properly apply the principles of retrograde extrapolation, as it was accepted in the scientific community. Additionally, the court rejected the defendant's argument that a per se violation (or a presumptive inference) could only be proven by a direct alcohol measurement. They argued that previous cases involvogin HGN and cases without blood or breath tests specifically held that per se violations could only be proven by chemical analysis. The court distinguished those cases and stated:

"Here, by contrast, a chemical analysis of defendant's breath was performed and provided the basis for Bessett's opinion. Bessett's testimony simply would have provided a range for defendant's BAC at 3:08 a.m. when defendant was stopped, based on the result of that chemical analysis, which was concluded at 4:42 a.m. Unlike the HGN test in O'Key or the observations of physical indicia of impairment in Ross and Johnson, Bessett's testimony was derived, using scientific principles, from a chemical analysis of defendant's breath. That testimony was admissible."

Editor's note: Interestingly, the opinion does not reflect what factors, other than a single-point breath test, supported an ability to perform the extrapolation of the BAC to any point in time. As most practitioners would agree, a single-point alcohol test, without evidence as to the time of consumption (or other factors such as amount and type of alcohol, weight of the individual, food consumption, etc.) is usually insufficinet to arrive at an opinion based upon a reasonable degree of certainty, which is the necessary strength an opinion must have to be admissible.

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