Defendant appeals a judgment of conviction for driving under the influence of intoxicants (DUII), ORS 813.010(1), and reckless driving, ORS 811.140. We reject, without further discussion, defendant’s first and second assignments of error in which he challenges the trial court’s denial of his motion for a judgment of acquittal.
I. BACKGROUND
The facts are undisputed. At around 9:00 a.m. on August 26, 2012, a security officer noticed defendant wandering around a Portland SmartPark garage. Between 9:50 and 10:00 a.m., a garage employee saw defendant on foot, and, soon thereafter, he saw defendant’s red car come down the ramp, pull up to the exit gate arm, pause for a few seconds, and quickly reverse back up the ramp in the wrong direction. Defendant’s car smashed into an unused pay booth.
Later that day, the security officer saw defendant walking outside the garage. The security officer summoned Officer Payton. Payton noticed that defendant was slightly swaying, smelled of alcohol, and had watery, bloodshot eyes. Defendant told Payton that he had backed into the pay booth, he had seen someone running after his car, he had not stopped, he had assumed that the police were called, and he had walked down the garage stairs to calm down.
Payton arrested defendant and took him to the police station, where he failed four of six field sobriety tests. Defendant said that he had had “four or five [drinks] at the bar” but had stopped drinking at 2 a.m. that morning. About two and one-half hours after the garage incident, an Intoxilyzer test at 12:36 p.m. revealed defendant’s BAC to be 0.06 percent. Defendant was charged with one count ofDUII, three counts of failure to perform duties of a driver when property is damaged, and one count of reckless driving.
Bessett testified that in order to perform a “retrograde extrapolation” — to “estimate a person’s BAC at a previous time” — he needed a time of the breath or blood test, a time that the drinking began, and a time of the “incident or the time of where you want the retrograde extrapolation to be.”
“Yes. As long as the person is qualified, trained and the person does not give the retrograde extrapolation to an exact result, meaning that I cannot say with a 100 percent certainty that somebody who blew a .06, let’s say, at 3:00 a.m., that they were — they had to be a .15 at 9:00 p.m. That’s unscientific because there’s a lot of variables.
“Each person is different. People’s livers work at different rates. A person’s liver even works at different rates on different evenings. So * * * what is known * * * through the peer-reviewed published studies is that the liver works in a range, meaning most, almost all people, drinkers that is, will eliminate alcohol between a .01 percent per hour and a .025 percent per hour.
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“[T]hese are normal drinkers, not children, and these are not people with excessively high BACs, let’s say of a .3, .4, .5 or higher. People who reach that amount, that high of a BAC, are probably two things, chronic alcoholics or that they binge drink, and when * * * you reach that high of a BAC your liver can work much faster than that .025 range, can be at .03, .04, .05.
“So I used a .01 to .025 for the majority or vast majority of people except for those excessively high BACs or chronic alcoholics that are up there quite often.”
When asked whether the analysis has a high failure rate, Bessett explained,
“If a person has enough information and gives a range, * * * I can be really confident that the person fits somewhere in that range based on peer-reviewed published material.
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“I try to limit the error by giving a large range and factoring in as much as I can and having known values.”
Bessett reiterated that “people absorb alcohol differently,” resulting in a range of possible BAC values that could have existed “back in time.”
Bessett discussed how the Widmark formula is used in performing retrograde extrapolation. That formula applies a mathematical equation using the “extrapolation time” and the time of the breath test. Certain variables such as the last time the person drank alcohol are significant. And, no drinking should have occurred after the traffic stop or incident. Bessett described how an estimate can be deduced about the number of drinks a person had consumed, “plus or minus 20 percent” due to individual variables. He testified that the formula is generally accepted in his field.
Defendant asserted that the retrograde extrapolation evidence should not be admitted at trial. He contended that Bessett “has not met the Brown /O’Key standards.” State v. Brown,
At trial, Bessett began by testifying about alcohol absorption and elimination rates. Because “peer-reviewed published studies” demonstrate that most people’s livers eliminate alcohol within a range of 0.01 to 0.025 percent per hour, Bessett said that he uses that range when making a retrograde extrapolation. It is a range that covers “the vast majority of people.” He testified that a person in defendant’s situation would have had a BAC of “at least a .08” at the point at which defendant was driving. That is the low end of a range that would be between a 0.08 and 0.11 BAC, given the variables that could alter the outcome of the analysis. The trial court admitted a copy of Bessett’s calculations into evidence. The jury ultimately found defendant guilty of driving under the influence, failure to perform the duties of a driver, and reckless driving.
On appeal, defendant reiterates that retrograde extrapolation should be inadmissible under OEC 702 and that the state failed to establish an adequate foundation in this case.
II. BROWN! O’KEY AND RETROGRADE EXTRAPOLATION
“Before applying the test for admissibility of scientific evidence, we must determine for what purpose the evidence is offered.” State v. Sampson,
“(1) A person commits the offense of driving while under the influence of intoxicants if the person drives a vehicle while the person:
“(a) Has 0.08 percent or more by weight of alcohol in the blood of the person as shown by chemical analysis of the breath or blood of the person made under ORS 813.100 [implied consent to breath or blood test], 813.140 [chemical test with consent] or 813.150 [chemical test at request of arrested person];
“(b) Is under the influence of intoxicating liquor, a controlled substance or an inhalant; or
“(c) Is under the influence of any combination of intoxicating liquor, an inhalant and a controlled substance.”
Accordingly, the state offered Bessett’s testimony in this case for the purpose of establishing
Generally, there are three fundamental requirements for expert testimony: (1) the witness’s qualification as an expert, (2) helpfulness of the expert’s testimony, and (3) an adequate foundation for the testimony.
The Supreme Court has supplied several factors to aid a trial court’s determination of whether scientific evidence is valid under OEC 702. Those factors include:
“(1) The technique’s general acceptance in the field;
“(2) The expert’s qualification and stature;
“(3) The use which has been made of the technique;
“(4) The potential rate of error;
“(5) The existence of specialized literature;
“(6) The novelty of the invention; and
“(7) The extent to which the technique relies on the subjective interpretation of the expert.”
O’Key,
Defendant’s appeal presents the question whether retrograde extrapolation — the mathematical process of plotting backwards an individual’s BAC using the Widmark formula — is scientifically valid. The record shows that retrograde extrapolation is dependent on two factors: (1) the body’s peak absorption of alcohol, and (2) the body’s elimination rate of alcohol from the blood. Defendant does not make challenges specific to either factor. Instead, he objects more generally to the admissibility of retrograde extrapolation as scientific evidence. See Sampson,
A. General acceptance in the field
In Baucum, we rejected the defendant’s contention that an expert’s testimony regarding retrograde extrapolation is inadmissible scientific evidence or “‘junk science’ that is not generally accepted in the relevant scientific community.”
In surveying other jurisdictions’ case law, we also observed “general acceptance of retrograde extrapolation, so long as the expert has sufficient information to determine where on the BAC curve — in the absorption phase, at the peak, or in the elimination phase — the defendant was at the time of the stop and at the time of the blood, urine, or breath test.” Id. We need not reiterate our observations nor reexamine that conclusion in Baucum. General acceptance in the field weighs in favor of admissibility.
B. Expert’s qualifications and stature
Although contested before the trial court, defendant does not challenge Bessett’s qualifications on appeal. We agree with defendant’s concession that, given Bessett’s testimony regarding his educational background, professional experience, and training, he is qualified to give expert testimony on retrograde extrapolation. O’Key,
C. Use of technique
As this court has previously noted, “there are two potentially pertinent considerations under [the “use”] factor— ‘how widely the protocol has been used’ and ‘the goal of the protocol.’” Reed,
Defendant concedes that retrograde extrapolation has been widespread in blood-alcohol analysis for quite some time. Although the record reflects that retrograde extrapolation is performed primarily to establish a person’s BAC for DUII prosecution, retrograde extrapolation is also pertinent to other alcohol-related litigation, as well as other disciplines such as pharmacology. Baucum,
In considering this factor, “[w]e focus on whether proffered scientific evidence has a rate of error low enough that its results can be trusted with ‘reasonable certainty.’” Sampson,
Bessett described the factors that make up a retrograde extrapolation and the variables that can affect an analysis. He explained that retrograde extrapolation is accepted in his field, so long as “the person does not give the retrograde extrapolation to an exact result [.]” That is because the “liver works in a range, meaning most, almost all people, drinkers that is, will eliminate alcohol between a .01 percent per hour and a .025 percent per hour.” He explained that absorption rates vary and account for a range of possible values in a retrograde extrapolation analysis. Given the number of variables that could affect a retrograde extrapolation, Bessett explained that it is important to provide a range, rather than a precise value of BAC, and that, in doing his calculations, he attempts to minimize error by giving a large range and factoring in as much as he can about known variables.
Bessett’s testimony is consistent with studies indicating that there is a wide but consistent range of rates within which alcohol is eliminated from a person’s blood. See Baucum,
Bessett’s testimony, although less developed about the variability of the body’s absorption of alcohol, is also consistent with studies noted in Baucum demonstrating that “the speed of a person’s peak absorption is dependent on variables such as the presence and type of food in the stomach, the person’s gender, the person’s weight, the person’s age, the person’s mental state, the drinking pattern, the type of beverage consumed, the amount consumed, and the time period of alcohol consumption.” Id. at 662 (internal quotation marks and emphasis omitted).
Retrograde extrapolation using the Widmark formula does not result in a precise BAC value, because experts use a range of rates to account for variation among individuals’ rates of absorption and elimination. However, the elimination rates used to make the calculation, here 0.01 to 0.025, result in a range of possible BAC values in which a defendant’s BAC is very likely to fall. Using a range that accounts for variability thereby serves as a check against a high rate of error. Bessett conformed to this practice and considered evidence of the time of the “incident” and had knowledge that no drinking had occurred after that incident while defendant was in custody. We conclude that operational standards favor admissibility.
E. Existence of specialized literature and peer review
As we noted in Baucum, there are many studies pertaining to factors affecting “the rate of alcohol absorption and the rate of elimination” and addressing the application of the Widmark formula to make retrograde extrapolation. Id. at 661.
Defendant acknowledges the existence of those studies, but he argues that they indicate a “lack of acceptance in the scientific community.” The studies cited by defendant, however, do not indicate that making retrograde extrapolation has been rejected or that peer-reviewed articles have discredited the underlying scientific theory of the evidence — that is, the Widmark formula. See Lyons,
F. Novelty
“Although novelty is a factor to be considered, it does not ‘imply invalidity.’ ” Reed,
G. Extent to which technique relies on expert’s subjective interpretation
Defendant argues that retrograde extrapolation relies on a subjective interpretation by the expert calculating a defendant’s BAC. In support of that argument, defendant contends that Bessett’s testimony indicated that experts may choose different ranges of elimination rate variables, here 0.01 to 0.025, and experts may vary with regard to which variables they believe are sufficient to calculate an accurate range of BAC values.
The parties do not dispute that conducting retrograde extrapolation requires some degree of subjective evaluation in addressing the variables that will likely affect the range of possible results. Nevertheless, conducting retrograde analysis in this case relied on the application of the Widmark formula, a mathematical formula that is not itself subject to an expert’s subjective revision. Bessett testified that, once necessary variables are known, an expert can insert the variables into the equation, as in algebra, to produce a range of possible results. To that extent, the evidence is verifiable and can be replicated by other experts in the field, including an expert retained by a defendant who may re-examine the evidence. See O’Key,
In light of our conclusions as to these factors, we hold that retrograde extrapolation evidence is admissible under OEC 702 with a qualified expert.
III. ADMISSIBILITY OF TESTIMONY
An expert may meet the requirements of OEC 702 by explaining “his or her own expertise, how he or she gathers and uses particular information, how that information informs his or her conclusions, and
In this case, Bessett testified to (1) his knowledge and experience performing retrograde extrapolation; (2) the basis of his knowledge, including his familiarity with peer-reviewed studies and his training; (3) his consideration of variables that affect alcohol elimination from the body; (4) the information he considered highly significant to conducting retrograde extrapolation; and (5) his reasoning in applying that evidence to the Widmark calculation. In light of that evidence, Bessett’s testimony regarding making a retrograde extrapolation in this case meets the admissibility requirements of OEC 702.
Our consideration of the Brown/O’Key factors leads us to conclude generally that retrograde extrapolation using the Widmark formula is scientifically valid. The foundation provided in this case was sufficient to meet the admissibility requirements of OEC 702. The trial court did not err in concluding that Bessett’s testimony was admissible.
Affirmed.
Notes
Defendant’s fourth, fifth, and sixth assignments of error are moot in light of the corrected judgment entered in the trial court that removed the unitary assessments under former ORS 137.290 (2011).
Retrograde extrapolation refers to “the mathematical process of plotting backwards [an individual’s] BAC on a BAC curve” after the individual has consumed alcohol. State v. Baucum,
The impact of the crash caused the booth to damage a vehicle parked behind it.
Defendant later prevailed on a motion for a judgment of acquittal on one count of failure to perform the duties of a driver and was acquitted of another.
Bessett noted that a retrograde extrapolation also requires a breath test result exceeding a 0.02 BAC because “top experts say * * * a person can hover at .01, .02 for several hours.”
Under Brown and O’Key, admissible scientific evidence must be relevant under OEC 401, helpful to the trier of fact under OEC 702, and not subject to exclusion under OEC 403. State v. Perry,
The state contends that the evidence is not “scientific.” We reject that argument without further discussion. State v. Whitmore,
OEC 702 provides:
“If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education may testify thereto in the form of an opinion or otherwise.”
We note that jurisdictions have come to different conclusions regarding admissibility requirements for peak absorption and elimination determinations involved in retrograde extrapolation. For instance, some jurisdictions require an expert to demonstrate knowledge of whether the defendant’s body was absorbing or eliminating alcohol at the time of a blood-alcohol test, sufficiently consider the eating and drinking history of a defendant in establishing peak absorption, or demonstrate where on a BAC curve a defendant’s BAC falls, in order for retrograde extrapolation evidence to be deemed reliable. Compare State v. Armstrong,
Defendant also argues that experts may use other formulas to make retrograde extrapolation. We do not address the scientific admissibility of other methods of retrograde analysis under OEC 702.
Although Bessett offered testimony about alcohol absorption at trial, defendant did not object to the testimony and does not otherwise raise a challenge on appeal to the scientific reliability of Bessett’s testimony as to peak absorption. We note that although the time needed to reach peak BAC is variable, defendant admitted that he had stopped drinking at 2:00 a.m. and several hours had already passed by the time his BAC was recorded during the breath test. As some scientific research indicates, peak absorption occurs within 75 minutes from the time an individual stops drinking, for 92 percent of individuals. Baucum,