Summary
In Hixon v. Tennessee Valley Auth. Bd. of Directors, 558 F.Supp.3d 573 (E.D. Tenn. 2021), the district court wrestled with allowing an expert to testify at trial regarding the employer's drug test potentially producing a false positive.
Summary of this case from Fisher v. Airgas U.S., LLCOpinion
Case No. 1:19-cv-120
09-07-2021
Alex HIXON, Plaintiff, v. TENNESSEE VALLEY AUTHORITY BOARD OF DIRECTORS, Defendant.
Douglas S. Hamill, Mikel & Hamill PLLC, Chattanooga, TN, for Plaintiff. David D. Ayliffe, James S. Chase, Mark Alan Mohr, Michael Vincent Bernier, Office of General Counsel, Knoxville, TN, Kathleen Keough Griebel, Office of General Counsel, 400 W. Summit Hill Drive, WT, for Defendant.
Douglas S. Hamill, Mikel & Hamill PLLC, Chattanooga, TN, for Plaintiff.
David D. Ayliffe, James S. Chase, Mark Alan Mohr, Michael Vincent Bernier, Office of General Counsel, Knoxville, TN, Kathleen Keough Griebel, Office of General Counsel, 400 W. Summit Hill Drive, WT, for Defendant.
ORDER
CHARLES E. ATCHLEY JR., UNITED STATES DISTRICT JUDGE
Before the Court is the Motion to Exclude Dr. Nicholas Wilton as an Expert Witness [Doc. 39] and Motion to Partially Exclude Dr. Dustin Sulak as an Expert Witness [Doc. 40], filed by Defendant Tennessee Valley Authority Board of Directors ("TVA"). For reasons that follow, TVA's Motion to Exclude Dr. Nicholas Wilton as an Expert Witness [Doc. 39] is DENIED IN PART and GRANTED IN PART and TVA's Motion to Partially Exclude Dr. Dustin Sulak [Doc. 40] is DENIED .
I. BACKGROUND
The Court assumes familiarity with the facts as set forth in Judge Collier's Memorandum on the parties' cross-motions for summary judgment. [Doc. 74 at 1–7]. The Court takes this opportunity to highlight those facts that are relevant to the instant motions.
For ease and consistency, record citations are to the electronically stamped CM/ECF document and page number, rather than any internal pagination.
Plaintiff Alex Hixon was subject to a random drug test in December 2013 while employed by TVA. [Doc. 23-1 at ¶ 8]. He informed his supervisor that the test result would be positive because he was prescribed a drug that would be detected by the test, [Doc. 26-1 at ¶ 5], and his prescription for Marinol was later submitted to TVA. [Doc. 23-1 at ¶ 8]. He was put off-duty with pay and benefits and an individualized medical assessment was scheduled. [Id. ]. TVA's Medical Review Officer ("MRO") submitted the sample for a second test by ElSohly Laboratories, Inc. [Id. at ¶ 10]. The test concluded that Plaintiff's positive THC result could not have been the result of Marinol alone, suggesting marijuana ingestion. [Doc. 41-2]. After being reinstated pursuant to a Last Chance Agreement that required him to submit a written list of his medications every month, he failed to timely submit this list. [Doc. 23-1 at ¶¶ 17-18]. He was terminated and brought suit for, inter alia , disability discrimination. [Doc. 23-1 at ¶ 18; Doc. 1].
On December 1, 2020, the Court denied Plaintiff's motion for partial summary judgment and granted in part and denied in part Defendant's motion for summary judgment. [Doc. 74 at 35; Doc. 75]. The Court found that a genuine issue of material fact exists as to whether Plaintiff was wrongfully terminated, precluding summary judgment on his disability discrimination claim. [Doc. 74 at 27-33]. Applying the McDonnell-Douglas framework, the Court first found that Plaintiff had made a prima facie case of disability discrimination. [Id. at 30]. TVA argued that the reasons for Plaintiff's termination were legitimate and non-discriminatory: he had violated the Last Chance Agreement and the second drug test indicated he lied about using marijuana. [See id. ]. Because violation of the Last Chance Agreement would be a valid, non-discriminatory reason for Plaintiff's discharge, the Court did not examine TVA's other proffered reason for discharging Plaintiff, namely, that he was untrustworthy. [Id. ].
Plaintiff introduced three pieces of evidence to demonstrate that TVA's reasons for terminating him were pretextual: (1) Plaintiff's supervisors did not give consistent reasons for firing him; (2) the letter for Plaintiff's termination was drafted two weeks before his termination; and (3) TVA's reliance on the drug test was objectively unreasonable. [See Doc. 74 at 31]. As Judge Collier explained in the Opinion, the record reflects differing accounts of why Plaintiff was fired. [Id. ]. Because shifting rationales can provide evidence of pretext, the Court found a genuine issue of material fact as to the reason for Plaintiff's discharge. [Id. at 32-33]. The Court did not consider Plaintiff's additional proof of pretext because the fact that different reasons were provided for his termination was sufficient to survive summary judgment. [Id. at 33 n.11]. Nor did it address TVA's honest belief rule argument.
The expert testimony at issue here concerns the test results from ElSohly Laboratories, Inc., conducted to determine if the presence of THC in Plaintiff's sample indicated marijuana use or could be attributed solely to Marinol. [Doc. 41-2]. The THCV test result was positive for THC-COOH ("THC") and THCV-COOH ("THCV"). [Doc. 41-2]. As described by TVA, "[t]he mechanics of the THCV test is [sic] simple. It uses the presence of the THCV metabolite in urine specimen results as a ‘marker’ for ingestion of marijuana." [Doc. 42 at 4]. THC is found in both marijuana and Marinol ; THCV is found only in marijuana. [Doc. 43 at 1]. The ElSohly Laboratories test of Plaintiff's specimen found THC present at a rate of 51ng/ml. [Doc. 41-2]. The test also found THCV at a rate of 21ng/ml. [Id. ]. The Analysis of Specimen concludes: "The presence of THCV metabolite in urine indicates prior ingestion of marijuana (or a related product) and cannot be the result of the sole use of Marinol." [Doc. 41-2]. It is signed by Dr. Mahmoud ElSohly. [Id. ].
Plaintiff maintains that the THCV test result was inaccurate and that the error would have been obvious to "any laboratory chemist." [Doc. 43 at 2]. He contends that the ratio of THC to THCV is highly unusual and indicates error. [Id. ]. Hixon identifies two expert witnesses who dispute the accuracy of Hixon's THCV test result, Dr. Dustin Sulak and Dr. Nicholas Wilton.
TVA challenges the testimony of both proffered experts on the basis that the accuracy of the THCV test is not relevant to Plaintiff's claims. TVA argues that the "honest belief rule" prevents Plaintiff from establishing pretext because regardless of the correctness of the test results, TVA honestly and reasonably relied on them. TVA also challenges the witnesses' expertise relative to their anticipated testimony and the reliability of their opinions.
TVA also contends Plaintiff was not terminated for drug use, presumably distinguishing drug use from Plaintiff's purported untrustworthiness regarding the test results. Judge Collier previously found a genuine issue of material fact as to the true reason for Plaintiff's termination, so the Court need not delve further into this distinction. [Doc. 42 at 14; Doc. 74 at 31-33].
II. STANDARD OF REVIEW
Before a witness can give an expert opinion, their testimony must meet the requirements of Federal Rule of Evidence 702 :
A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:
(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied the principles and methods to the facts of the case.
Fed. R. Evid. 702. The Court acts as a "gatekeeper" of evidence that fails to meet this standard. Daubert v. Merrell Dow Pharms., Inc. , 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993) ; Kumho Tire Co., Ltd. v. Carmichael , 526 U.S. 137, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999). Yet, the Rule 702 inquiry is "a flexible one," Daubert , 509 U.S. at 594, 113 S.Ct. 2786, and "rejection of expert testimony is the exception, rather than the rule," In re Scrap Metal Antitrust Litig. , 527 F.3d 517, 530 (6th Cir. 2008). "Vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence." Daubert , 509 U.S. at 596, 113 S.Ct. 2786 ; see also United States v. 14.38 Acres of Land , 80 F.3d 1074, 1078 (5th Cir. 1996) ("[T]he trial Court's role as a gatekeeper is not intended to serve as a replacement for the adversary system.").
As explained by the United States Court of Appeals for the Sixth Circuit, a proposed expert's opinion is admissible under Rule 702 if it satisfies three requirements: (1) the witness is qualified by knowledge, skill, experience, training, or education; (2) the testimony is relevant; and (3) the testimony is reliable. In re Scrap Metal Antitrust Litig. , 527 F.3d at 529. Testimony is relevant if it relates to a fact at issue and helps the jury determine that fact. Fed. R. Evid. 401 ; Navarro v. Procter & Gamble Co. , 501 F. Supp. 3d 482, 489 (S.D. Ohio 2020). Testimony is reliable if it is based on "something ‘more than subjective belief or unsupported speculation.’ " Id. (citing Daubert , 509 U.S. at 590, 113 S.Ct. 2786 ). "[A] reliable opinion requires that the expert use (1) a reliable methodology, and (2) base his or her opinion on reliable facts or data." Id. ; see In re Scrap Metal , 527 F.3d at 529. Reliability is different than credibility and accuracy. Id. The Court is not concerned with the "correctness or truthfulness of such an opinion." Id. It is concerned only with whether the testimony "rests on a reliable foundation." Conwood Co., L.P. v. Tobacco Co. , 290 F.3d 768, 791 (6th Cir. 2002) (quoting Hardyman v. Norfolk & W. Ry. Co. , 243 F.3d 255, 260 (6th Cir. 2001) ).
III. ANALYSIS
A. Dr. Sulak
TVA moves to exclude Dr. Sulak's opinions regarding (1) the THCV test, (2) the specific impact of Marinol on Plaintiff, and (3) the likelihood of Marinol abuse or diversion.
i. Opinion of THCV Test
TVA argues that Dr. Sulak's opinions regarding the THCV test should be excluded (a) because they would not assist the trier of fact in understanding issues relevant to the case, (b) because Dr. Sulak lacks expertise regarding the THCV test, and (c) because his opinions regarding the THCV test lack a demonstrable scientific basis. First, TVA argues that the accuracy of the THCV drug test "is not material to the central issue before this Court." [Doc. 41 at 9]. TVA maintains that it honestly relied on the drug test result in determining that Hixon had been dishonest and thus the accuracy of the result is immaterial. [Id. at 9-10]. Hixon argues that the accuracy of the test result is relevant to whether TVA's reason for terminating him was pretextual. [Doc. 44 at 7]. He further argues that TVA has used the test to challenge his credibility and truthfulness and will likely do so at trial. [Doc. 44 at 10]. TVA does not disclaim reliance on the test for this purpose.
To establish that an employer's explanation for an adverse employment action is a pretext for discrimination, a plaintiff must show (1) that the stated reasons for the employer's action had no basis in fact; (2) that the stated reasons for the employer's action were not the actual reasons; or (3) that the stated reasons for the employer's action were insufficient to explain the adverse action taken. Perryman v. Postmaster General , 475 F. App'x 585, 587 (6th Cir. 2012). But an employer is entitled to judgment in its favor when it demonstrates that it "reasonably and honestly relies on particularized facts in making an employment decision ... even if its conclusion is later shown to be ‘mistaken, foolish, trivial, or baseless.’ " Babb v. Maryville Anesthesiologists , 942 F.3d 308, 322 (6th Cir. 2019) (quoting Chen v. Dow Chem. Co. , 580 F.3d 394, 401 (6th Cir. 2009) ). "[A]n employee can still overcome the ‘honest belief rule’ by pointing to evidence that ‘the employer failed to make a reasonably informed and considered decision before taking its adverse employment action.’ " Id. (quoting Smith v. Chrysler Corp. , 155 F.3d 799, 807-808 (6th Cir. 1998) ).
As noted in the Court's Memorandum on summary judgment, Plaintiff presented evidence that TVA's reasons for terminating him were pretextual, including that reliance on the THCV test was objectively unreasonable. [Doc. 74 at 31-32]. In response to TVA's Daubert motions, Plaintiff further argues that the THCV test results "should have been a red flag error to any laboratory chemist, prompting at least review or retest." [Doc. 43 at 11]. Plaintiff urges that TVA failed to make a reasonably informed decision in terminating him, either because the result was flawed or because it was contradicted by other facts known to TVA. [Doc. 44 at 8-9]. TVA counters that the honest belief rule hinges not on the accuracy of the test or what a laboratory chemist would have honestly and reasonably believed about the results. [Doc. 45 at 6-7]. Rather, the applicability of the honest belief rule depends on what the employer honestly and reasonably believed. [Id. ]. Yet Plaintiff was employed by TVA as a Chemistry Laboratory Technician and his immediate supervisor was a Chemistry Laboratory Supervisor. [Doc. 32 at 1; Doc. 19-6 at 2]. Neither party pointed the Court to sufficient evidence in the record to allow the Court to determine whether the THCV test result should have appeared questionable to the individuals at TVA who were responsible for its review. And Plaintiff also argues that TVA had ample proof from other sources that Plaintiff had not used marijuana, including information from his treating physicians. [Doc. 44 at 9]. Whether TVA made a reasonably informed and considered decision in terminating Plaintiff is a disputed fact issue that remains for the jury.
The parties develop their relevance arguments in the separate briefing on each motion. The arguments pertain to both motions and the Court has therefore considered them together, regardless of where they appear in the briefing.
The Court need not resolve this dispute, however, because TVA concedes that it intends to impeach Hixon with the results of the failed drug test. [Doc. 45 at 5 n.2]. Federal Rule of Evidence 608(b) makes inadmissible "extrinsic evidence ... to prove specific instances of a witness's conduct in order to attack or support the witness's character for truthfulness." Fed. R. Evid. 608(b). But the Rule allows inquiry into such issues on cross-examination "if they are probative of the character for truthfulness or untruthfulness of the witness." Id. TVA has contended in this case that Hixon refused to "admit to his illegal drug use" and "falsely and repeatedly claimed that his positive drug test result was caused by Marinol." [See, e.g. , Doc. 27 at 1]. TVA now anticipates introducing testimony regarding the THCV drug test "to explain TVA's motivations for its employment actions and not merely to impeach Hixon. " [Doc. 46 at 5 n.2 (emphasis added)]. Because TVA intends to impeach Hixon with the THCV test results, whether Hixon may use the test to show pretext or to bolster his own credibility is not determinative. TVA's response indicates the accuracy of that test will be at issue, and Hixon's evidence on the topic cannot be excluded.
Second, TVA argues that Dr. Sulak does not have the necessary expertise to offer an opinion about the THCV test results. [Doc. 41 at 10]. TVA contends Dr. Sulak's experience is limited to examining plant compounds and that he lacks experience analyzing human metabolites. [Id. at 11]. TVA argues that he has not performed any laboratory work, but only observed a laboratory where tests were conducted on marijuana plants, not human or biologic samples. [Id. at 9]. While he ordered drug tests for people, TVA says he did not conduct the drug tests himself. [Id. at 9–10]. Finally, TVA argues that Dr. Sulak has never received specific training on the THCV drug test. [Id. at 10]. It concedes, however, that Dr. Sulak is qualified to testify in general about the use of Marinol. [Id. at 8].
Dr. Sulak has sufficient expertise to give an opinion on the THCV test. He is a licensed physician with over ten years of clinical experience working with medical cannabis and four years of experience as medical director of a cannabis analytical laboratory. [Doc. 32-6 at ¶ 2]. He has two bachelor of science degrees, in which he studied organic chemistry and analytic chemistry. [Doc. 41-1 at 7]. He testified that he has been attending scientific conferences on cannabis and cannabinoids for about a decade, with an average of about five conferences per year. [Id. at 9]. He has authored four peer-reviewed articles on medical cannabis, as well as portions of a continuing medical education curriculum regarding cannabis for clinicians. [Doc. 44-1 at 21, 28]. He testified that he has taught courses that were relevant to his opinions in this case, including pharmacology of cannabis "which includes its absorption and metabolism and excretion." [Id. at 22]. He has experience collecting drug samples, performing urinalysis tests, and interpreting drug screens. [Id. at 16-17; Doc. 41-11 at 14]. Though he often delegates the task to his medical assistant, he also reviews the results himself. [Doc. 44-1 at 17]. He has analyzed "hundreds" of cannabis samples over the years. [Id. at 60]. Finally, he has provided expert testimony regarding a positive urine drug screen and the use of CBD products, which involved analyzing "the THC metabolites that appear in the urine drug screen and correlating that with what the individual might have consumed that resulted in" the positive test result. [Doc. 44-1 at 5-6].
The record does not reflect whether he was deemed an expert in this matter. Nonetheless, his work generating a report in that case indicates further experience on substantially similar subject matter.
Plaintiff has comfortably carried his burden of showing by a preponderance of proof that Dr. Sulak is qualified by knowledge, skill, experience, training, and education to testify regarding the THCV test. In addition to his training, education, and study, he supplemented his knowledge by relying on peer-reviewed studies regarding the THCV test. [Doc. 41-1 at 3-4]. TVA repeatedly urges that Dr. Sulak does not have experience or training regarding this specific drug test, but the Court's analysis of expertise is not so granular, nor is it apparent that such particularized training is necessary to understand the THCV test. According to TVA, the mechanics of the THCV test are simple. [Doc. 42 at 4]. Dr. Sulak is well-qualified to give an opinion regarding the test.
Where a witness has general expertise in a broad area but is not a specialist in the particular aspect of the field involved in the case, most courts find that the lack of specialization goes to the weight of the testimony, not its admissibility. See 29 Charles Alan Wright & Arthur Miller, Fed. Prac. & Proc. Evid. § 6264.2, n.15 (2d ed. 2021).
Finally, TVA argues that Dr. Sulak's opinions regarding the THCV test are unreliable because they lack a demonstrable scientific basis. TVA attacks Dr. Sulak's opinions as "purely speculative and unreliable." [Doc. 41 at 14]. But Dr. Sulak testified that he questioned Hixon's results because of the high level of THCV present in Hixon's sample. [Doc. 44-1 at 58]. In reaching this conclusion, he considered the availability of THCV in samples of cannabis, which he has analyzed hundreds of over the years. [Id. at 60-61]. He also reviewed a study conducted by ElSohly Laboratories, Inc., the lab that analyzed Hixon's urine sample. [Id. ; Doc. 41-1 at 3-4]. It was not methodologically unsound for Dr. Sulak to analyze a positive test result for THC and THCV on the basis of (i) a study regarding THC and THCV detection, and (ii) extensive experience working with and studying these compounds. TVA's arguments in this regard go to the weight of Dr. Sulak's testimony, not its reliability.
TVA also faults Dr. Sulak for not identifying "inherent flaws" in the test and for offering alternative explanations, concluding he "was unable to provide any support for his assertion of laboratory error." [Doc. 41 at 15]. But Dr. Sulak testified that several factors caused him to "question the data," including the ratio of THC to THCV found in Plaintiff's sample. [Doc. 41-11 at 80-81, 83-84]. And " Rule 702 ... does not require anything approaching absolute certainty." Tamraz v. Lincoln Elec. Co. , 620 F.3d 665, 671-72 (6th Cir. 2010).
Similarly, TVA contends Dr. Sulak cannot "support his claim that ElSohly's THCV test lacks scientific validation." [Doc. 41 at 15; see Doc. 41-1 at 5]. Yet Dr. Sulak testified that the basis for his opinion was that two other studies that have looked at this issue have found that THCV is not a valid biomarker. [Doc. 41-11 at 82]. According to TVA, Dr. Sulak misinterprets those peer-reviewed studies. [Doc. 41 at 16]. It argues the studies he relied on demonstrate the potential for false negatives, while Dr. Sulak opines that Hixon's THCV test produced a false positive. [Id. ]. But the Court analyzes methods, not conclusions. Dr. Sulak's conclusion may be inaccurate, but that is a question for the jury. Daubert , 509 U.S. at 594–95, 113 S.Ct. 2786. Likewise, TVA's list of perceived deficiencies in Dr. Sulak's knowledge and investigation, see Doc. 41 at 16-17, may be appropriate topics of inquiry at trial, but they are not free-standing grounds for exclusion of his testimony.
ii. Opinion of Marinol's Impact on Hixon
Second, TVA objects to Dr. Sulak offering testimony about Marinol's effect on Hixon because he lacks a factual basis to do so. [Doc. 41 at 15]. His report states: "It is my professional opinion that dronabinol was a safe and effective treatment for Mr. Hixon and that he could have performed his work duties safely while on the treatment." [Doc. 41-1 at 8]. Dr. Sulak testified that he formed this opinion based on Hixon's self-evaluation and his clinical experience that dronabinol can be effective for Hixon's conditions. [Doc. 41-11 at 86]. Because Marinol affects people differently, TVA argues an individualized assessment was necessary to determine the effects of Marinol on Hixon. [Doc. 41 at 18]. Because Dr. Sulak did not clinically evaluate Hixon, did not review his medical charts or doctor's notes, and was not aware of the severity of Hixon's mental health conditions, TVA argues he lacks a sufficient factual basis to opine on the safety and efficacy of Marinol for Hixon. [Id. ; Doc. 41-11 at 53].
Dr. Sulak has prescribed Marinol to several hundred patients over the years. [Id. at 11, 59-60]. As Defendant concedes, he is qualified to opine on the general effects of taking Marinol, including its side effects, general efficacy, potential dangers of taking Marinol, and contraindications. [Doc. 41 at 8]. As set forth in his report and deposition, Dr. Sulak reviewed Hixon's job description, Marinol dosage, his other medications, and an interaction report for those medications, which was confirmed by his clinical experience. [Doc. 41-1 at 2-3; Doc. 32-6 at ¶ 3]. He was aware that Hixon was taking dronabinol for treatment of anxiety and sleep disturbance, and that Marinol was prescribed to reduce or replace Ativan. [Id. ]. The verbal report he received indicated that Hixon had initially experienced some side effects that made him want to take Marinol at night rather than during the day. [Doc. 41-11 at 64].
Dr. Sulak testified that the severity of a patient's depression would not impact his ability to safely take Marinol. [Doc. 41-11 at 53]. He testified that he would closely monitor a patient during "any trial" to see what their response is and determine if there was improvement or worsening of their symptoms and side effects. [Id. ]. He testified that a patient's self-report is how he would determine if Marinol is causing impairment and that patients who are impaired using THC are typically aware of their impairment and able to report and compensate for it. [Doc. 41-11 at 46-47]. He further testified that an "appropriate dose" would be "a dose at which the patient does not report any adverse effects." [Doc. 41-11 at 66-67]. At an appropriate dose, Dr. Sulak opined that Marinol would not impact Hixon's ability to perform his work safely. [Id. at 66].
Dr. Sulak's extensive experience with Marinol, his review of Hixon's dose, other prescriptions, symptoms, and receipt of Hixon's informal self-evaluation provide a sufficient factual basis from which to opine that Marinol was a safe and effective treatment for Hixon. Though TVA argues Hixon's self-reporting is an inadequate basis for this opinion, Dr. Sulak testified that self-reporting is how he determines impairment and efficacy for his patients. [Doc. 41-11 at 45-46, 66-67]. The other information Dr. Sulak could have reviewed before forming his opinion may be considered by the jury in determining the weight and credibility of his testimony. It is not sufficient to render that testimony wholly unreliable under Rule 702.
iii. Opinion Regarding Abuse or Diversion of Marinol
Third, TVA objects to Dr. Sulak's opinion that Marinol is not often diverted or abused by patients. Dr. Sulak makes this observation based off of a study—which TVA criticizes as biased—and his experience in treating patients. [Doc. 44 at 15]. Dr. Sulak acknowledged the possibility of bias in the study, but noted that the study was based on a combination of published literature, databases regarding drug abuse trends, a review of Internet sources, and expert opinions. [Doc. 41-11 at 50]. He also testified that he has some experience treating patients with addiction and substance abuse issues. [Id. at 15, 17]. According to Dr. Sulak, prescribing Marinol to someone with addiction issues would not typically be harmful, because oral administration of THC is less likely to produce "reward system" effects. [Id. at 48].
Dr. Sulak's experience treating patients, coupled with his review of a peer-reviewed study on the topic, is a sufficient factual basis for his opinion that Marinol is not commonly abused or diverted. That the study he relied on may be biased effects the weight of the testimony, not its admissibility, and can be explored on cross-examination. Daubert , 509 U.S. at 596, 113 S.Ct. 2786.
B. Dr. Wilton
TVA moves to entirely exclude Dr. Nicholas Wilton as an expert witness. TVA contends that (1) Dr. Wilton is not qualified to opine on the THCV test; (2) Dr. Wilton's opinion that the test results suggest "analytical error" is irrelevant and unreliable; and (3) Dr. Wilton's opinions regarding Dr. ElSohly's study are unreliable.
i. Opinions Regarding THCV Test
TVA first argues that Dr. Wilton is not qualified to give expert opinions regarding the THCV test or the results of Hixon's test. TVA argues Wilton did not study urinalysis as student, has not had training related to urinalysis, has not worked in this area, and has no experience analyzing human metabolites of marijuana. [Doc. 42 at 10, 12]. TVA urges that the "sole basis" for his opinion regarding the test results is his review of the literature. [Id. ]. According to TVA, Dr. Wilton's education and general experience do not make him an expert in analyzing urinalysis results and do not qualify him to render an opinion on the THCV test. For similar reasons, TVA contends Dr. Wilton is not qualified to testify regarding the validity of Dr. ElSohly's clinical study or the efficacy of the THCV test generally. As further support, TVA notes that Dr. Wilton has no experience with clinical studies on biological samples or specialized knowledge regarding the THCV test. TVA urges that urinalysis is "a specialized area of science requiring expertise" that Dr. Wilton lacks. [Doc. 45 at 5].
Dr. Wilton is an analytical chemist with bachelor and doctorate degrees in chemistry. [Doc. 39-5 at 2]. TVA concedes he has general experience as a chemist and specific experience with gas chromatography-mass spectrometry (GC-MS). [Doc. 42 at 9]. GC-MS is the technology used to derive the results for analysis in the THCV test. [Doc. 42 at 4 n.2]. Within the field of analytical chemistry, Dr. Wilton testified his specialty is chromatography. [Id. ]. The main component of his background in research is GC-MS. [Id. at 4-5]. Even more specifically, Dr. Wilton specializes in standardized systematic errors in GC-MS and in analysis of compounds and metabolites within cannabis and hemp. [Id. at 4-6].
While Dr. Wilton has not specifically worked with urinalysis or drug test results, he testified that he has analyzed compounds "in more complex matrices, and the nature of this analysis is not particularly different from the analysis of the cannabinoids that I look at as part of my routine daily work." [Doc. 43-1 at 6]. His research focuses on methods used by government and private laboratories who employ GC-MS, though not specifically urinalysis or drug test results of biological samples. [Doc. 43-1 at 6-7]. He testified, however, that "the analysis of these compounds is not fundamentally different." [Id. at 7]. He also testified that while the THC to THCV ratio in direct testing of cannabis differs from the ratio in metabolites, the ratio "will be somewhat proportional to the flower, even if it is not identical." [Doc. 39-1 at 52-53].
Dr. Wilton further testified that as the Director of Analytics with Healer, LLC, a producer of high-end cannabis extracts, he worked to develop analytical standard operating procedures for, among other things, GC-MS. [Doc. 43-1 at 20-21]. He explained that these methods were designed to look at cannabinoids "such as THC and THCV." [Id. at 22-23].
Dr. Wilton's knowledge, education, experience, and training in the field of analytical chemistry, and his specialization in GC-MS and analysis of cannabinoids, make him well-qualified to render an opinion on the THCV test. "Where a witness is qualified in a general relevant field, the witness's lack of familiarity with specific aspects of the specialized field at issue merely goes to the weight and credibility of the testimony, not its admissibility." Univ. of Pittsburgh v. Townsend , 2007 WL 1002317, *12 (E.D. Tenn. March 30, 2007) ; see First Tenn. Bank Nat'l Ass'n v. Barreto , 268 F.3d 319, 333 (6th Cir. 2001) (extent to which expert "lacked familiarity with some aspects of banking relationships ... merely affected the weight and credibility of his testimony, not its admissibility"). Even if, as TVA contends, urinalysis is a specialized area of science requiring expertise, Dr. Wilton has dealt specifically and extensively with GC-MS, the method used to obtain Hixon's THCV test result, and he has direct experience analyzing THC and its structural isomers and analogues. [Doc. 43-2 at 4]. He also supplemented his research and experience with peer-reviewed studies on the topic. [Doc. 39 at 3-5]. He is therefore qualified to opine on the THCV test and Hixon's test results.
ii. "Analytical Error" Opinion
Dr. Wilton questions the result of Plaintiff's drug test because, in Wilton's opinion, it is uncharacteristic of illicit cannabis or the urinary excretions of cannabis users, "showing significantly higher THCV metabolite than expected by orders of magnitude." [Doc. 39-2 at 3]. Dr. Wilton explains that in an illicit cannabis flower, THC is present at ~12% by weight on average, while THCV is a minor constituent of the flower at ~0.1% on average, for a ratio of ~120.1 in a typical cannabis flower. [Id. ]. The report acknowledges that ratios derived from urine tests will vary from ratios obtained from direct testing of cannabis. [Id. ]. Dr. Wilton compares Hixon's result to the ratios obtained in three studies: the 2011 Levin study, the 2017 Andersson study, and the 2001 ElSohly study. [Id. at 3, 5]. Based on his assessment of these studies, he concludes that the THC to THCV metabolite ratio in Hixon's test was highly unusual, making it reasonable to suspect that the result was obtained in error. [Id. at 4]. According to Dr. Wilton, the "most likely explanation" for the chemical profile in Hixon's drug test is analytical error. [Doc. 39-2 at 3].
TVA argues that Dr. Wilton's opinion that an analytical error occurred is irrelevant to the issues in this case. [Doc. 42 at 14]. As set forth above, because TVA intends to impeach Hixon's credibility with the THCV test results, Hixon can offer evidence that the result was inaccurate. When properly instructed, the Court does not believe the jury will be confused by expert testimony regarding the THCV test or its scientific basis.
Next, TVA argues that Dr. Wilton's opinion is unreliable, because it is speculative, based on insufficient facts and data, and involves too large an inferential gap between his opinion and the underlying information. TVA argues that Wilton entirely bases his opinion that the test results are unusual on his review of two studies, [Doc. 42 at 7], though his report indicates he reviewed the 2001 ElSohly Laboratories study as well. [Doc. 39-2 at 3]. TVA does not agree with Wilton's analysis, claiming he "posits an arbitrary baseline" for the amounts of THC and THCV in drug test results and then compares his "novel ratio opinion" to Hixon's results. [Doc. 42 at 7, 17].
The record does not substantiate TVA's assertion that Wilton used a "single, distinguishable study to establish a baseline of what ‘proper’ results should look like." [Doc. 42 at 15]. And, as with Dr. Sulak, TVA's attempt to distinguish the Levin Study because it relates to false negatives rather than false positives goes Dr. Wilton's conclusions and not the reliability of his opinion. [Doc. 42 at 7].
But what TVA is really challenging is Dr. Wilton's conclusions regarding the referenced studies and his judgment that the results can be compared to Hixon's test results. Dr. Wilton's report and deposition testimony demonstrate that he relied on his experience and education in examining on-topic peer-reviewed studies and, based on this research, came to an opinion regarding Hixon's test result. This is a sufficient factual basis for his opinion. Dr. Wilton may draw inferences from existing research on the subject matter without creating a "string" of speculation that district courts have been warned against admitting. Cf. Tamraz , 620 F.3d at 672 ("Dr. Carlini's opinion contains not just one speculation but a string of them: A suggests by analogy the possibility of B, which might also apply to C, which, if we speculate about D, could eventually trigger E, so perhaps that happened here."). Here, TVA has not set forth any reason why Dr. Wilton's method—assessing test results based on related peer-reviewed studies and his own knowledge, education, and experience—is unreliable. TVA specifically challenges Wilton's testimony that an acceptable ratio of THC to THCV would be a range of 100:1 to 500:1. [Doc. 42 at 16]. In his deposition, TVA's counsel asked Wilton what an acceptable ratio of THC to THCV would be. [Doc. 39-1 at 64]. Wilton responded that "in general, samples have somewhere between roughly 100:1 and maybe 500:1." [Id. ]. TVA seizes on Dr. Wilton's description of this range as "an off-the-cuff value" based on the referenced studies. [Id. ]. But this answer does not transform his opinion, expressly based on his review of related scientific studies, into a "subjective belief or unsupported speculation." [See Doc. 42 at 17 (citing Smelser v. Norfolk S. Ry. Co. , 105 F.3d 299, 303 (6th Cir. 1997) (abrogated on other grounds))]. TVA's characterization of Dr. Wilton's opinion as "admittedly speculat[ive]" similarly takes his testimony out of context. [See Doc. 42 at 16].
TVA goes on to list several purported deficiencies and inconsistencies in Dr. Wilson's reasoning and testimony—that he failed to consider alternative explanations, "strained" to distinguish the ElSohly data, implicitly criticized a study on which he also relied, and failed to specifically identify the source of the analytical error he believes occurred. [Doc. 42 at 17-18]. Again, these issues go to the credibility and weight of Dr. Wilton's testimony. They do not render his opinion unreliable.
iii. Opinion on Dr. ElSohly's 2001 Study
Lastly, TVA contends that Dr. Wilton's opinion regarding Dr. ElSohly's 2001 clinical study must be excluded because it is not based on sufficient facts and data. [Doc. 42 at 18]. Dr. Wilton's report acknowledges that the 2001 ElSohly Labs clinical study showed similar ratios to that in Hixon's test. [Doc. 39-2 at 3]. He questions the study because the cannabis used in the trial "had an unusually low THC content." [Id. ]. He further notes that the trial had no sample group that had previously consumed both Marinol and cannabis, "making quality control of results much more difficult in this test." [Id. at 4]. He testified that the ElSohly study was "the primary basis" for the THCV test and "one of the most flawed clinical studies" he had ever seen, noting the study was of only four people. [Doc. 39-1 at 30]. He clarifies, however, that this does not mean the test is fundamentally flawed. [Doc. 39-2 at 4]. Finally, he opines that the THCV test is not widely used and testified that GC-MS has fallen out of favor. [Doc. 39-2 at 3; Doc. 39-1 at 43]. He bases this conclusion on his inability to locate academic work in the quantity he would expect if the test were widely used. [Doc. 39-1 at 43-44].
TVA argues Wilton's opinion regarding the ElSohly test is irrelevant. Yet TVA relies on the study to explain how the THCV test works, [Doc. 42 at 5], and identifies the study as an exhibit it may introduce at trial. [Doc. 61 at 4]. And Hixon's THCV test, which concludes that the presence of THCV metabolite shows ingestion of marijuana and not solely Marinol, is signed by Dr. Mahmoud ElSohly, who performed the 2001 ElSohly Labs study. [Doc. 41-2]. TVA's argument that the study is irrelevant is unpersuasive.
Dr. Wilton's declaration, report, and deposition testimony set forth a sufficient basis for him to opine on the accuracy of Dr. ElSohly's 2001 study. Dr. Wilton has knowledge and experience regarding the THC content of the cannabis flower and related compounds and his research and work experience relate to systemic errors in GC-MS analysis, creating a factual basis for his opinions regarding the ElSohly study.
A broad and prolonged criticism of this study, however, may run afoul of the limits set forth by Federal Rule of Evidence 403. That will depend on the extent and purpose of the testimony offered, and as a result the Court cannot determine its admissibility before trial.
In contrast, Dr. Wilton's impression that the THCV test is not "widely used" and that the "technology has fallen out of favor" does not appear to be based on any experience or research, but rather his inability to locate an expected volume of academic work on the topic. [See Doc. 39-2 at 3; Doc. 39-1 at 43]. "An expert's work is admissible only to the extent it is reasoned, uses the methods of the discipline and is founded on data. Talking off the cuff—deploying neither data nor analysis—is not an acceptable methodology." Higgins v. Koch Dev. Corp. , 997 F. Supp. 2d 924, 931 (S.D. Ind. 2014) (quoting Lang v. Kohl's Food Stores, Inc. , 217 F.3d 919, 924 (7th Cir. 2000) (internal quotation marks omitted)). The absence of academic papers or search engine results regarding the THCV test is not a sufficient basis for Dr. Wilton to opine that the THCV test is not widely used. It is also not clear from the record why the test's widespread or niche use would be relevant to whether it was accurate in a particular instance. This opinion will therefore be excluded. Plaintiff likewise does not point to a sufficient basis for Dr. Wilton's opinion that GC-MS has fallen out of favor.
Finally, TVA challenges Dr. Wilton's statement in his report that the efficacy of the ElSohly Labs THCV test has been contested. [Doc. 42 at 20]. His report cites to the 2011 Levin study and to Brian Sedgwick's 2000 research letter to support this statement. [Doc. 39-2 at 5]. TVA argues that the Sedgwick article questioned the THCV test because there was not enough information on THCV at the time. [Doc. 42 at 20]. According to TVA's memorandum, Dr. Wilton testified that the science on THCV has since developed. [Id. ]. The cited portion of Dr. Wilton's deposition was not filed, so the Court is unable to fully assess this testimony. Nonetheless, Dr. Wilton supports his opinion that the efficacy of the test has been contested by reference to an academic article and peer-reviewed study, so his opinion is neither misleading nor unreliable.
TVA cites to Wilton's deposition transcript, 105:17-107:5, but pages 106 and 107 do not appear in the excerpt filed. [See Doc. 39-1 at 49-50].
With the exception of Dr. Wilton's opinion that the THCV test is not widely used, TVA's challenges to Dr. Wilton's testimony present a "battle of the experts," and in such a battle "the jury must decide the victor." Ambrosini v. Labarraque , 966 F.2d 1464, 1468 (D.C. Cir. 1992) (quoting Ferebee v. Chevron Chemical Co. , 736 F.2d 1529, 1535 (D.C. Cir. 1984) ).
IV. CONCLUSION
For the reasons stated above, the Motion to Partially Exclude Dr. Dustin Sulak [Doc. 40] is DENIED and the Motion to Exclude Dr. Nicholas Wilton as an Expert Witness [Doc. 39] is DENIED IN PART and GRANTED IN PART .