Daubert Doesn’t Look Much Different from Howerton When it Comes to Retrograde Extrapolation

The court of appeals gave the green light last week for law enforcement officers to continue to testify as scientific experts in DWI cases involving retrograde extrapolation–notwithstanding the legislature’s amendment of Rule 702 to adopt the Daubert standard. The court held in State v. Turbyfill that a field technician for the Forensic Test for Alcohol Branch of DHHS (FTA), who was trained as a law enforcement officer and chemical analyst (which authorized him to conduct implied consent testing on breath testing instruments), was properly allowed to testify about a retrograde extrapolation calculation he performed using an FTA form. The technician’s inability to explain whether the rate he used to make the calculation was an “average,” a “mid-point,” or a “conservative” rate—he used all three terms to describe it—did not disqualify him as an expert since he “provided the trial court with a list of some thirty-nine articles . . . regarding blood alcohol research,” and “with North Carolina cases in which this Court upheld the use of retrograde extrapolation to establish blood alcohol content.”

Facts. The defendant in Turbyfill ran off an Asheville road in his truck one evening in December 2011.  The officers who responded to the accident noted that the defendant slurred his words, his eyes were bloodshot, he was unsteady on his feet, and he had an odor of alcohol on his breath. The 20-year-old defendant admitted to drinking alcohol—a 24 ounce Smirnoff—and to taking prescription medicine earlier in the day. He performed multiple field sobriety tests, during which the officers noted several clues of intoxication. The defendant was arrested for DWI and submitted to a breath test, which registered a blood alcohol concentration of 0.07.

At trial. Anthony Burnette, a field technician for FTA since 2005, was tendered as an expert witness at trial in blood alcohol physiology, pharmacology, and “related research on retrograde extrapolation.” Like nearly all (if not all) FTA employees, Burnette was employed as a law enforcement officer before joining the branch.  He was certified as a chemical analyst—a designation that allows a law enforcement officer to perform breath testing of defendants charged with implied consent offenses. Burnett testified that he was required to “stud[y] the pharmacology of alcohol and how alcohol is distributed through the body” to maintain his certification. He also testified that he was an FTA instructor in “standardized field sobriety covering the pharmacology of alcohol, pharmacokinetics, and the effects of alcohol on the brain and body.” He said he had attended ten workshops with FTA research scientist Paul Glover “with regard to pharmacology of alcohol, retrograde extrapolation,” had assisted in more than 100 cases involving retrograde extrapolation and had testified as an expert in retrograde extrapolation 28 times. [Glover’s qualifications and his research, which primarily consists of conducting controlled drinking exercises to measure breath alcohol concentration, are discussed in some detail in State v. Green, 209 N.C. App. 669 (2011).]

Expert opinion. Burnette testified to his opinion that defendant’s BAC at the time of the accident was a .10. He reached this conclusion by multiplying an alcohol elimination rate of .0165 an hour by the 1.83 hours that elapsed between the accident at the time the defendant took the breath test and adding the sum to the 0.07 alcohol concentration that registered on the breath test.

Burnette said the “.0165 per hour originally came from a study that Dr. Ellis at the University of North Carolina had done years ago,” which had been confirmed in subsequent studies included in the reference list of publications marked as State’s Exhibit 4. He testified that in performing his analysis that he had used the same method and principles used in those studies and did not deviate in any way from them.

State’s Exhibit 4. No study by a Dr. Ellis appears in the reference list Burnette provided. And a review of the abstracts of a handful of the studies listed reveals that they arrived at varying elimination rates. The abstract from one of these studies states that “although the average patient presenting to the emergency department will clear ethanol at about 20 mg/dL/h, a standard deviation of 6 mg/dL/h means that only 83% of these patients will have clearance rates between 8 and 32 mg/dL/h, and that if accurate estimates are necessary, serial determinations of two or more levels are needed.” Only one test was used to calculate Turbyfill’s earlier alcohol concentration.

Court’s analysis. The court of appeals construed the defendant’s contention on appeal to be limited to the expert’s qualifications rather than an objection to his application of the formula he used. The court faulted the defendant for his failure to present an argument explaining how Burnette’s lack of understanding regarding the basis for the formula disqualified him as an expert in its application. The court held “that because the calculations themselves were based on well-recognized and accepted scientific formula and applicable methodology, the terminology (mis)used by the expert, while perhaps troubling from the standpoint of basic mathematical concepts, was not critical to his qualification.” That explanation notwithstanding, I have difficulty grasping this distinction.  In any event, the court concluded that Burnette’s “specialized knowledge, skill, experience and training” were “sufficient for the trial court to allow him to testify as an expert in blood alcohol physiology, pharmacology, and related research on retrograde extrapolation.”

More than math.  As the abstract excerpt quoted above reveals, “[t]he process and rate at which alcohol is eliminated from the body are complicated scientific matters that are beyond the skill, knowledge, and comprehension of the average person.” See People v. Barham, 788 N.E.2d 297, 307 (Ill. App. 2003).  Rather than simply involving the application of an “average” elimination rate, determination a person’s alcohol concentration at an earlier time “is a complex scientific evaluation that is impacted by a number of variables,” id., among them a person’s weight and gender, drinking pattern, how much the person drank, the duration of the drinking, and how much the person had to eat. See Mata v. State, 46 S.W.3d 902, 916 (Tex. Crim. App. 2001).

My two cents. The Turbyfill court passed up the opportunity to reconsider its previously liberal approach to the qualification of scientific experts and the admission of retrograde extrapolation testimony in light of amended Rule 702. The testimony deemed admissible in Turbyfill sharply contrasts with that recently deemed improperly admitted by an appellate court in Illinois. There, the court in People v. Floyd held that testimony from a forensic toxicologist, who determined that the defendant’s blood alcohol concentration at the time of driving “was between 0.082 and 0.095,” should not have been admitted at the defendant’s DWI trial, even though the toxicologist explained that two conditions must be met for the calculation to be valid:  (1) the person metabolizes alcohol at the normal rate; and (2) the person is no longer absorbing alcohol and is in the elimination phase when the breath test is administered. Floyd, 11 N.E.3d 335, 338 (Ill. App. 2014), reh’g denied (July 11, 2014), appeal denied, 23 N.E.3d 1203 (Ill. 2015). The Floyd court explained that the “introduction of Weinstein’s retrograde extrapolation calculation, when many necessary factors were unknown and when only one breath test was administered, invited the jury to convict her due to a reaction to a supposedly high BAC rather than proof beyond a reasonable doubt that defendant was driving under the influence.” Id. at 341.

3 thoughts on “Daubert Doesn’t Look Much Different from Howerton When it Comes to Retrograde Extrapolation”

  1. I would like to comment on the procedural issues raised in Turbeyville, because I think the point to some important procedural changes in light of the new Rule 702. The page numbers I refer to are from the slip opinion.

    The first thing to note is that the issue on appeal concerned the cross examination of Burnette. The court noted (4) that admission of expert testimony is reviewed for abuse of discretion. Burnette was qualified as an expert (9-10) . The record indicates that at trial Burnette describe the method of retrograde extrapolation (10-13). This indicates that this testimony was elicited on direct examination in front of the jury. The same is true with respect to the second issue (13), but in this case the testimony cited in the slip opinion is from cross examination.

    By the time the matter is before the jury, the gatekeeper role of the trial judge is complete – the horse is out of the barn. Because there was no voir dire, the only question on appeal was whether the decision of the trial court to let Burnette testify was whether the decision was so irrational as to constitute abuse of discretion (4). Because no objection was made to admission of the testimony, it was technically not even subject to appellate review. See State v. Cunningham, 188 N.C. App. 832 (2008) (holding no plain error review for discretionary ruling under Rule 403).

    With respect to the second issue (19), the Court found no plain error with respect to the testimony of officer Lovelace. Here, no objection was raised during trial to the officer’s testimony. However, the court found such testimony was not properly admitted under Rule 702(a1) because he gave an opinion as to the specific alcohol concentration as it related to the results of the HGN test performed. Because the rule specifically states that testimony as to the specific alcohol concentration is not allowed, no objection was necessary to preserve the issue for appellate review. The court found plain error, but then found the error to be harmless.

    I think the take home point of Turbyville is this: the trial judge will serve as gatekeeper only where the matter is challenged by way of voir dire, or at least some questioning before the expert is tendered and qualified as an expert. An attack on the expert by cross examination after the witness has been qualified as an expert will not preserve the issue of whether the witness was properly qualified as an expert for appellate review.

    Perhaps if the expert screws up testimony during trial bad enough, a motion to strike the testimony may be sufficient to preserve the issue for appellate review (that did not apparently happen in this case). I also think it is an open question as to whether the issue can be raised and the voir dire conducted during trial or whether the motion must be filed and litigated in limine. I think that is going to be the next issue for the court to consider.

    I believe Turbyville has given us the contours for how to handle such cases in the future. I do not believe that it has made it impossible to challenge expert testimony on extrapolation in all cases. I think it has merely tells us how to do it in superior court in the future.

  2. In my opinion, far to seldom does the defense hire its own expert in these retrograde cases. I realize that it can be expensive, but without an actual pharmacologist or serologist testifying about how wildly unreliable this average elimination rate methodology is, the judge and jury are going to wind up siding with the only guy who spoke on the issue.

    My inclination in these cases is to first challange the officer’s admission as an expert and his specific testimony, in lemine. A real expert should be called at this pre-trial hearing. Then, if it is still admitted into evidence, give up final arguement so that the jury can hear from a real scientist that this stuff is unreliable.

    Additionally, a good defense expert can really mine into those publications that Paul Glover has put out and relies on. In my experiance, he cites himself an aweful lot and his research lacks the level of rigor and reproducability that is expected in respected scientific academic publications. He will, of course, never admit such things on the stand (and he has been testifing for a long time and is very good at it), so you need a good expert to rip away the facade of authority.


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