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5 6 7 8 UNITED STATES DISTRICT COURT WESTERN DISTRICT OF WASHINGTON 9 AT SEATTLE 10 11 CHEYANNE [DIXSON] ROSA, CASE NO. 2:24-cv-01673-TL 12 Plaintiff, ORDER ON MOTION TO EXCLUDE v. DEFENDANT’S EXPERT 13 CITY OF ISSAQUAH, a municipal 14 corporation in and for the State of Washington, 15 Defendant. 16
17 18 This matter is before the Court on Plaintiff’s motion to exclude Defendant’s expert 19 Dr. John Lynch. (Dkt. No. 20). Having considered the motion, Defendant’s response (Dkt. 20 No. 28), Plaintiff’s reply (Dkt. No. 33), the relevant record, and oral argument presented on 21 August 28, 2025, the Court DENIES the motion. 22 // 23 // 24 // 1 I. BACKGROUND1 2 The Court assumes familiarity with the facts of this case, which arises out of Plaintiff’s 3 2022 termination as a police officer with the Issaquah Police Department after Defendant, the 4 City of Issaquah, determined it could not accommodate Plaintiff’s religious exemption to
5 vaccination against SARS-CoV-2, an employment requirement implemented by Defendant 6 during the COVID-19 pandemic.2 See generally Dkt. No. 1-2 (Complaint). 7 On January 21, 2025, Defendant produced the expert report of John Lynch, M.D., a 8 board-certified physician in infectious disease. Dkt. No. 21-1 (Lynch Report). Lynch’s proffered 9 testimony includes background information on the COVID-19 pandemic and the development of 10 the first COVID-19 vaccines (see id. ¶¶ 7–32), as well as opinions including that 11 (1) “Vaccination against COVID-19 is . . . extremely safe[] and highly effective at 12 preventing transmission of the virus and especially severe disease and death,” and 13 no other public health strategy is as effective in combatting COVID-19. Id. ¶ 69. 14 (2) “Mitigation techniques such as masking, testing, and social distancing are inferior
15 to vaccination” (id. ¶ 95), and no data supports their use as a substitution for 16 vaccination (id. ¶ 92). 17
1 As an initial matter, the Court notes that Plaintiff’s counsel has not met this Court’s standards of quality in the 18 briefing on this motion or other submissions to the Court. Plaintiff’s instant motion and reply are riddled with typographical errors and improper citations. As just one example, page 13 of the motion includes citations to 19 opinions from cases called “Liv v. Ne. Univ.,” “Qhine v. Buttigieg,” and, simply, “Neal Lomax.” Dkt. No. 20 at 13. As neither a complete federal reporter citation nor an electronic database identifier was provided for any of the three, 20 and as the docket number provided for “Liv” was incorrect, it took some effort for the Court to decipher that the opinions counsel intended to cite were actually Li v. Northeastern University, No. C22-444, 2023 WL 3722227 21 (W.D. Wash. May 30, 2023), Rhine v. Buttigieg, No. C20-1761, 2022 WL 7729817 (W.D. Wash. Sep. 15, 2022), and Neal-Lomax v. Las Vegas Metropolitan Police Department, 574 F. Supp. 2d 1193 (D. Nev. 2008). On the same page, counsel uses a short citation for “Daubert I,” evidently Daubert v. Merrell Dow Pharmaceuticals., Inc., 509 22 U.S. 579 (1993), although Daubert is not cited elsewhere in the motion. These and numerous similar errors and inconsistent formatting choices presented challenges for the Court and delayed its ruling on this motion. This type of 23 submission is not at the level of quality that this Court expects. 2 For simplicity, the Court will refer in this order to both the SARS-CoV-2 virus and the disease it causes as 24 “COVID-19.” 1 (3) COVID-19 (a) is spread via aerosols that are transmitted over distances, even if 2 the infected person is masked, (b) can persist in indoor spaces after the person 3 leaves, and (c) can be spread outdoors. Id. ¶¶ 65–66. 4 (4) Police officers have some of the highest risks of COVID-19 exposure and also
5 “interact with individuals and groups of people from communities of color, 6 notably the Hispanic and Pacific Islander/Native Hawaiian communities, which 7 were disproportionately impacted by COVID-19 infections, severe disease, and 8 death.” Id. ¶¶ 65-66. 9 (5) “Data available at the time [of Plaintiff’s termination] established that an 10 unvaccinated person posed materially higher risks of transmitting COVID-19, 11 including increasing the potential for causing an outbreak, contracting 12 COVID-19, and developing severe disease, compared with a vaccinated person.” 13 Id. ¶ 95. 14 (6) Based on Plaintiff’s job duties and the data available at the time, allowing
15 Plaintiff to work unvaccinated, even with other mitigation measures in place, 16 “would have significantly increased the risk that Plaintiff would infect co-workers 17 and members of the public with COVID-19 or contract the virus herself.” Id. 18 After Defendant moved for summary judgment (Dkt. No. 14), Plaintiff moved to exclude 19 all testimony by Dr. Lynch (Dkt. No. 20). Defendant opposes the motion. Dkt. No. 28. 20 II. LEGAL STANDARD 21 A. Expert Witness Testimony 22 Federal Rule of Evidence (“FRE”) 702 provides that “a witness who is qualified as an 23 expert by knowledge, skill, experience, training, or education may testify” if
24 (a) the expert’s scientific, technical, or other specialized 1 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 2 facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert’s opinion reflects a reliable 3 application of the principles and methods to the facts of the case. 4 This imposes an obligation on a district court to act as a gatekeeper and evaluate the 5 admissibility of expert opinion testimony to ensure that such evidence “is not only relevant, but 6 reliable.” See Kumho Tire Co. v. Carmichael, 526 U.S. 137, 147 (1999) (quoting Daubert v. 7 Merrell Dow Pharms., Inc., 509 U.S. 579, 589 (1993)); see also Estate of Barabin v. 8 AstenJohnson, Inc., 740 F.3d 457, 463 (9th Cir. 2014) (en banc) (“We have interpreted Rule 702 9 to require that expert testimony be both relevant and reliable.” (citation modified)), overruled on 10 other grounds by United States v. Bacon, 979 F.3d 766 (9th Cir. 2020) (en banc). 11 “[E]xpert opinion testimony is relevant if the knowledge underlying it has a valid 12 connection to the pertinent inquiry.” Engilis v. Monsanto Co., No. 23-4201, 2025 WL 2315898, 13 at *3 (9th Cir. Aug. 12, 2025) (quoting Alaska Rent-A-Car, Inc. v. Avis Budget Grp., Inc., 738 14 F.3d 960, 969 (9th Cir. 2013)). Expert opinion “is reliable if the knowledge underlying it has a 15 reliable basis in the knowledge and experience of the relevant discipline.” Id. (quoting Alaska 16 Rent-A-Car, 738 F.3d at 969); see also Gen. Elec. Co. v. Joiner, 522 U.S. 136, 146 (1997) 17 (noting opinion evidence should not be admitted “that is connected to existing data only by 18 the ipse dixit of the expert” or where there is “simply too great an analytical gap between the data 19 and the opinion proffered”). 20 To assess the reliability of an expert opinion, courts ordinarily look to such factors as 21 (1) whether the expert’s theory or technique can be tested, (2) whether it has been subjected to 22 peer review and publication, (3) its known or potential error rate, and (4) whether it enjoys 23 general acceptance within the relevant community. Estate of Barabin, 740 F.3d at 463 (citing
24 Daubert, 509 U.S. at 592–94) (“The Supreme Court has suggested several factors that can be 1 used to determine the reliability of expert testimony . . . .”). This is a flexible inquiry, however, 2 and the trial court has discretion to decide how to assess the reliability of opinion testimony 3 based on the circumstances of each case. Primiano v. Cook, 598 F.3d 558 (Apr. 27, 2010) 4 (quoting Kumho Tire Co., 526 U.S. at 141, 152). The court may, but is not required to, hold a
5 “Daubert hearing” to determine the relevance and reliability of an expert opinion. Estate of 6 Barabin, 740 F.3d at 463–64. 7 A “proponent of expert testimony ‘has the burden of establishing that the pertinent 8 admissibility requirements are met by a preponderance of the evidence.’” Engilis, 2025 WL 9 2315898, at *5 (quoting Fed. R. Evid. 702 advisory committee’s note to 2000 amendment). In 10 evaluating proffered expert testimony, “the district court is ‘a gatekeeper, not a fact finder.’” 11 Elosu v. Middlefork Ranch Inc., 26 F.4th 1017, 1020 (9th Cir. 2022) (quoting Primiano, 598 12 F.3d at 568). “Shaky but admissible evidence is to be attacked by cross examination, contrary 13 evidence, and attention to the burden of proof, not exclusion.” Id. at 1028 (quoting Primiano, 598 14 F.3d at 564).
15 B. Exclusion of Relevant Evidence 16 Like all evidence, expert testimony must be relevant in order to be admissible. Evidence 17 is relevant if “(a) it has any tendency to make a fact more or less probable than it would be 18 without the evidence; and (b) the fact is of consequence in determining the action.” Fed. R. Evid. 19 401; see also United States v. Hankey, 203 F.3d 1160, 1171 (9th Cir. 2000). 20 “Rule 403 of the Federal Rules of Evidence allows a trial judge to exercise [their] 21 discretion to exclude relevant evidence if its probative value is substantially outweighed by the 22 danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations 23 of undue delay, waste of time, or needless presentation of cumulative evidence.” Emmons v.
24 Orange, 46 F. App’x 444 (9th Cir. 2002) (citing Fed. R. Evid. 403); accord United States v. 1 Espinoza-Baza, 647 F.3d 1182, 1189 (9th Cir. 2011) (“district court has discretion to exclude 2 even relevant evidence” under Rule 403). 3 III. DISCUSSION 4 Plaintiff asks the Court to exclude all testimony by Defendant’s proposed expert,
5 Dr. John Lynch. Dkt. No. 20. Plaintiff asserts that Dr. Lynch is not qualified to opine as an 6 expert except on the “efficacy of [CV-19] vaccines”3 (id. at 7 (brackets4 in original)), that his 7 opinions are irrelevant (id. at 7, 9, 11) and unreliable (id. at 13–16), and that his testimony and 8 report will confuse the issues and should be excluded (id. at 10, 11, 12). 9 A. Rule 702 Challenge 10 In exercising its gatekeeper role, the Court will evaluate Dr. Lynch’s expert 11 qualifications, as well as the relevance and reliability of his proffered opinion testimony. 12 1. Dr. Lynch’s Qualifications 13 Dr. Lynch is a board-certified physician in infectious disease. Dkt. No. 30 (Lynch Decl.) 14 ¶ 1. He currently works as an Associate Medical Director of Harborview Medical Center and a
15 Professor of Medicine at the University of Washington (UW) and actively practices medicine as 16 an infectious disease clinician. Id. His work at Harborview includes serving as the medical 17 director for the occupational health program, and he also served on the Board of Directors of the 18 Infectious Diseases Society of America from 2019 to 2022. Id. ¶¶ 1, 5. From February 2020 until 19 December 2023, Dr. Lynch was the Medical-Technical Team Lead for UW Medicine’s 20 COVID-19 Emergency Operations Center, in which role he oversaw all UW Medicine’s
21 3 Elsewhere, Plaintiff asserts that “the singular issue” on which Dr. Lynch is qualified to opine is “[w]hether masking and testing was an effective method to reduce” Plaintiff’s risk. Dkt. No. 20 at 13. As the efficacy of 22 COVID-19 vaccines and the effectiveness of a testing/regime to reduce Plaintiff’s risk directly relate to all the proffered opinions, it is not entirely clear which opinions Plaintiff believes Dr. Lynch is not qualified to offer. 23 4 The meaning of this and other uses of brackets in Plaintiff’s briefing, in passages that do not appear to contain quoted material, is unclear. See, e.g., Dkt. No. 20 at 4, 7, 8, 9, 16; Dkt. No. 23 at 12, 13; Dkt. No. 24 at 7, 9, 27, 29; 24 Dkt. No. 33 at 3, 5, 6, 7, 9. 1 Personal Protective Equipment (PPE) and testing policies and was involved in the vaccination 2 rollout for employees. Id. ¶¶ 2, 6. While Plaintiff asserts there is only “one published article 3 attributable to Lynch” (Dkt. No. 20 at 9), this is unsupported. Dr. Lynch’s CV in fact identifies 4 82 peer-reviewed publications. Dkt. No. 30 at 16–27. Fifteen of these articles are about
5 COVID-19 and appear to have contributed to the developing scientific understanding of viral 6 transmission and best practices for prevention and response. Id. Dr. Lynch was a leader and 7 decisionmaker on the front lines of the public health response to COVID-19 from the very first 8 case identified in the United States (in Everett, Washington) throughout the entirety of UW’s 9 emergency response. Id. ¶¶ 2, 6. These facts demonstrate that Dr. Lynch is abundantly qualified 10 by both experience and training to render the opinions he offers. Plaintiff has not produced 11 evidence to negate these qualifications, and the suggestion that Dr. Lynch has only “read[] other 12 expert’s [sic] reports [as] any doctor could do” is not only unfounded but also untethered from 13 the actual facts.5 Dkt. No. 20 at 8. 14 As other courts have found, “Dr. Lynch is qualified as an expert on infectious diseases
15 generally and COVID-19 specifically,” Petersen v. Snohomish Reg’l Fire & Rescue, 16 No. C22-1674, 2024 WL 278973, at *6 n.13 (W.D. Wash. Jan. 25, 2024), aff’d, No. 24-1044, 17 2025 WL 2503128, at (9th Cir. Sep. 2, 2025) (quoting with approval the district court’s 18 conclusion regarding Dr. Lynch’s qualifications). The Court further FINDS that this expertise 19 qualifies Dr. Lynch to render the opinions he offers in this case. 20 // 21 // 22 5 The Court will give Plaintiff’s counsel the benefit of the doubt and not assume counsel was trying to intentionally mislead the Court. However, given numerous errors in Plaintiff’s briefing, see supra n.1, the combined assertions 23 that Dr. Lynch only had one published article and only read other experts’ reports, and counsel’s failure to acknowledge and apply the applicable standard for physician experts, the Court is left wondering if perhaps this 24 language was copied and pasted from a challenge to a different expert in a different case. 1 2. Relevance of Opinions 2 “Expert opinion testimony is relevant if the knowledge underlying it has a ‘valid . . . 3 connection to the pertinent inquiry.’” United States v. Sandoval-Mendoza, 472 F.3d 645, 654 4 (9th Cir. 2006) (omission in original) (quoting Kumho Tire, 526 U.S. at 149). “Relevancy simply
5 requires that ‘[t]he evidence . . . logically advance a material aspect of the party’s case.’” Estate 6 of Barabin, 740 F.3d at 463 (alteration and omission in original) (quoting Cooper v. Brown, 510 7 F.3d 870, 942 (9th Cir. 2007)). 8 Defendant offers Dr. Lynch’s testimony in support of its “undue hardship” defense to 9 Plaintiff’s claim, under the Washington Law Against Discrimination, that Defendant 10 discriminated against her by failing to accommodate her sincerely held religious belief. Dkt. 11 No. 28 at 3–4, 9; see also Dkt. No. 4 (answer to complaint) at 11 ¶ 71, 19 ¶ 2 (asserting defense). 12 To prevail on its undue hardship defense, Defendant will need to establish that the 13 accommodation sought by Plaintiff—here, remaining unvaccinated and fulfilling her usual job 14 duties but submitting to twice-weekly COVID-19 tests, masking during work hours while in the
15 presence of others, and eating her meals in her car, outdoors, or off site—would result in 16 “substantial increased costs in relation to the conduct of [Defendant’s] particular business.” 17 Williams v. Legacy Health, No. 22-6004, 2024 WL 3993162, at *6 (W.D. Wash. Aug. 29, 2024) 18 (quoting Groff v. DeJoy, 600 U.S. 447 at 470–71 (2023)). “Costs” that courts consider are not 19 limited to financial expenditures but also include non-monetary impacts such as an 20 “accommodation’s effect on co-workers” that “may have ramifications for the conduct of the 21 employer’s business,” Groff, 600 U.S. at 472, as well as any “cost to an employer’s mission.” 22 Lavelle-Hayden v. Legacy Health, No. C22-1752, 2024 WL 3822712, at *10 (D. Or. Aug. 14, 23 2024). “An accommodation that creates unreasonable safety risks, regardless of economic costs,
24 also presents an ‘undue hardship’ for an employer.” Suarez v. State, 3 Wn.3d 404, 427, 552 P.3d 1 786 (2024); see also Lavelle-Hayden, 2024 WL 3822712, at *10. 2 In the COVID-19 context, “[n]umerous courts have found the possibility of an 3 unvaccinated individual getting others sick to be a non-speculative risk that a court may consider 4 when performing an undue hardship analysis.” Bordeaux v. Lions Gate Ent., Inc., 703 F. Supp.
5 3d 1117, 1136 (C.D. Cal. 2023) (collecting cases). One critical dispute of fact related to these 6 claims is the amount of health- and safety-related risk (and thus the amount of burden) a 7 defendant would have taken on in accommodating an unvaccinated employee. Facts at issue in 8 resolving this question here include Plaintiff’s risk of contracting or spreading COVID-19 with 9 her accommodations in place, as well as the comparable risk of Plaintiff contracting or spreading 10 COVID-19 if she did not require accommodation (that is, if she became vaccinated and followed 11 Defendant’s general rules for its employees). Facts about how the virus that causes COVID-19 is 12 spread, and the danger posed by the virus to different groups of people, are relevant in evaluating 13 the potential consequences to Defendant of Plaintiff contracting or transmitting COVID-19 in her 14 role as a police officer. Finally, because an employer asserting an undue hardship defense cannot
15 be “judge[d] . . . with the clarity of hindsight or the benefit of post-pandemic debates over what 16 measured responses frontline employers should have taken,” expert testimony about what 17 information would have been available to Defendant in late 2021 and early 2022 about the 18 comparative effectiveness of vaccination and its alternatives is relevant. Petersen, 2025 WL 19 2503128, at *9. 20 Plaintiff repeatedly asserts that information about vaccines and safety risks is irrelevant 21 but does not explain how the health- and safety-related cost Plaintiff’s unvaccinated status 22 imposed on Defendant can be evaluated without this information. See, e.g., Dkt. No. 20 at 7 23 (vaccine efficacy is “not relevant to the inquiry”); id. at 9–10 (“Plaintiff is not contesting the
24 importance of vaccines and this information would not assist the trier of fact in determining if 1 masking, testing, and social distancing are reasonable . . . .”); id. at 11 (“safety risks for 2 unvaccinated individuals . . . do[] not help a trier of fact decide if masking and testing were 3 reasonable accommodations . . . .”); id. (opinions on benefits of vaccination “have nothing to do 4 with the issues in this case”). The one argument Plaintiff presents as to why these topics are
5 irrelevant—“because the Plaintiff was exempt from the vaccine requirement . . . .” (id. at 12)— 6 would appear to foreclose any consideration of health risks or other intrinsic “costs” of waiving 7 an employment requirement for an objecting employee. But it is hard to see how an undue 8 burden defense could ever be adjudicated without information about the purpose and value of the 9 employment requirement from which a plaintiff is exempt or seeking exemption. 10 The Court FINDS that Dr. Lynch’s opinions are relevant. 11 3. Reliability of Opinions 12 Reliability requires the court to assess “whether an expert’s testimony has ‘a reliable 13 basis in the knowledge and experience of the relevant discipline.’” Estate of Barabin, 740 F.3d 14 at 463 (quoting Kumho Tire, 526 U.S. at 149). In making its reliability determination, a court is
15 concerned with the soundness of the methodology, not with the correctness of the expert’s 16 conclusions. Id.; accord Primiano, 598 F.3d at 564 (“[T]he test under Daubert is not the 17 correctness of the expert’s conclusions but the soundness of his methodology.” (alteration in 18 original) (quoting Daubert v. Merrell Dow Pharms., Inc. (“Daubert II”), 43 F.3d 1311, 1313 (9th 19 Cir. 1995), on remand from Daubert, 509 U.S. 579)). Federal Rule of Evidence 702 provides that 20 “an expert may testify ‘in the form of an opinion or otherwise’ if his or her ‘specialized 21 knowledge will assist the trier of fact to understand the evidence or determine a fact in issue.’” 22 Hankey, 203 F.3d at 1167 (quoting Fed. R. Evid. 702). As the Ninth Circuit has explained: 23 Testimony by physicians may or may not be scientific evidence like the epidemiologic testimony at issue in Daubert. . . . Medicine is not a science but a 24 learned profession, deeply rooted in a number of sciences and charged with the 1 obligation to apply them for man’s benefit. Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making 2 decisions about the care of individual patients. Despite the importance of evidence-based medicine, much of medical decision-making relies on judgment— 3 a process that is difficult to quantify or even to assess qualitatively. Especially when a relevant experience base is unavailable, physicians must use their 4 knowledge and experience as a basis for weighing known factors along with the inevitable uncertainties to make a sound judgment. 5 Primiano, 598 F.3d at 565 (citation modified). When courts consider the admissibility of 6 testimony based not on scientific testimony but on some “other specialized knowledge,” as here, 7 Rule 702 generally is construed liberally. Hankey, 203 F.3d at 1168. 8 “When considering the applicability of Daubert criteria to [testimony by physicians 9 based on their knowledge and experience], the inquiry must be flexible.” Primiano, 598 F.3d at 10 565. Medical experts like physicians commonly base their opinions on their clinical experience 11 as well as treatises and research published, as well as reliable data collected, by others. See, e.g., 12 In re Phenylpropanolamine (PPA) Prods. Liab. Litig., 289 F. Supp. 2d 1230, 1248 (W.D. Wash. 13 2003) (experts relied on case and adverse drug reports, textbooks and treatises, and the clinical 14 experience of several experts and other scientists); Hopkins v. Dow Corning Corp., 33 F.3d 15 1116, 1124-25 (9th Cir. 1994) (expert opinion based on experience as a toxicologist, review of 16 medical records and Dow studies, and general scientific knowledge from animal studies and 17 biophysical data). However, “[p]eer reviewed scientific literature may be unavailable because the 18 issue may be too particular, new, or of insufficiently broad interest, to be in the literature.” 19 Primiano, 598 F.3d at 565. This “[l]ack of certainty is not, for a qualified expert, the same thing 20 as guesswork. Expert opinion testimony is . . . reliable if the knowledge underlying it has a 21 reliable basis in the knowledge and experience of the relevant discipline.” Id. (citation modified). 22 Finally, the Ninth Circuit in Primiano provided the following guidance for applying Daubert to 23 physicians’ testimony: “‘A trial court should admit medical expert testimony if physicians would 24 1 accept it as useful and reliable,’ but it need not be conclusive because ‘medical knowledge is 2 often uncertain.’” Id. (quoting Sandoval-Mendoza, 472 F.3d at 655). The Ninth Circuit has 3 further clarified that the reliability of experience-based expert testimony should be assessed on 4 factors including “whether the expert’s experience supports the expert’s conclusions; whether the
5 expert’s reasoning is circular, speculative, or otherwise flawed; [and] whether the expert’s 6 reasoning is adequately explained.” United States v. Holguin, 51 F.4th 841, 855 (9th Cir. 2022) 7 (internal citations omitted). 8 Dr. Lynch explains in his declaration that his opinions were formed based on knowledge 9 gained in “decades of working in clinical infectious diseases, infectious disease research, public 10 health, and epidemiology,” the medical studies and public health data he cites in his declaration 11 and report, his review of over a dozen documents from this case, and a visit to the Issaquah 12 Police Department. Dkt. No. 16 ¶¶ 5–6. This is clearly consistent with the types of sources 13 typically relied on by medical professionals. Though Defendant provides extensive case law on 14 medical expert testimony in its response (see Dkt. No. 28 at 6), Plaintiff offers no reply, ignoring
15 entirely this Circuit’s case law on expert testimony by medical professionals (see generally Dkt. 16 No. 33). Nor does Plaintiff acknowledge the factors relevant to the reliability of experience- 17 based expert testimony, as provided in Holguin—and, unrebutted, in Defendant’s response. See 18 generally id.; see Dkt. No. 28 at 6 (citing Holguin, 51 F.4th at 855). Instead, on reply, Plaintiff 19 reiterates her critiques that Dr. Lynch employs “no methodology” (Dkt. 33 at 8), “ha[s] not done 20 any antigen testing research” (id. at 7), and “is a physician at a hospital, not a scientist” (id. at 8). 21 These assertions miss the mark. In ignoring the applicable standards, Plaintiff presents no clear 22 argument that Dr. Lynch’s experience does not support his conclusions (and the Court finds that 23 it does); that his reasoning is circular, speculative, or otherwise flawed (and the Court finds that
24 it is not); or that his reasoning is not adequately explained (and the Court finds that is is). See 1 Holguin, 51 F.4th at 855. Accordingly, the Court finds that Dr. Lynch’s opinions have “a reliable 2 basis in the knowledge and experience of the relevant discipline.” 3 Reliability under FRE 702 also requires that expert testimony “reflects a reliable 4 application of the principles and methods to the facts of the case.” Fed. R. Evid. 702(d). Plaintiff
5 argues that Dr. Lynch’s opinions are unreliable (and also irrelevant) because of certain facts he 6 did not consider related to the specific masks and tests Plaintiff used during her temporary 7 accommodation (and presumably would have continued to use if accommodated long term). See, 8 e.g., Dkt. No. 20 at 8 (Lynch not qualified because “unaware what type of test was utilized” by 9 Plaintiff); id. at 11 (“lack of specific knowledge” about Plaintiff’s N-95 mask “fit test,” if any, is 10 “fatal to the relevance inquiry”); id. at 15–16 (Dr. Lynch’s opinion “is not reliable” because he 11 does not analyze the “specific testing and masking program applied” to Plaintiff). But Dr. Lynch 12 clearly opines that there was “no combination” of masks, tests, and other mitigations available to 13 Defendant “equivalent to those same mitigations, or a subset of those mitigations, in addition to 14 vaccination.” Dkt. No. 21-1 ¶ 50. Plaintiff herself points out that Dr. Lynch supports his opinion
15 on testing with both a meta-analysis of the effectiveness of antigen tests and data on PCR tests— 16 that is, he has considered any test Plaintiff could possibly have used. Dkt. No. 20 at 15; see also 17 Dkt. No. 21-1 ¶¶ 42–44. And several of the limitations Dr. Lynch identifies—for example, that 18 employers cannot require masking outside work, or that a person can become infected and 19 infectious between one test and the next—apply regardless of mask or test type. See Dkt. 20 No. 21-1 ¶¶ 50, 46. In any event, attacks on experts arising from “the variables [allegedly] not 21 considered are relevant to weight[,] not admissibility.” Elec. Mirror, LLC v. Avalon Glass & 22 Mirror Co., No. C16-665, 2018 WL 5785385, at *1 (W.D. Wash. Nov. 5, 2018). 23 Further, where the particular facts of the case are relevant to Dr. Lynch’s opinions, he
24 considers them with specificity. For example, he considers Plaintiff’s work duties, the settings in 1 which she worked, and the people with whom she interacted in her role as a police officer. Id. 2 ¶¶ 86–87. Plaintiff’s about-face argument that relying on these details constitutes “overreach” 3 because Dr. Lynch “is not a general witness with personal knowledge” (Dkt. No. 20 at 15) fails 4 under FRE 703, which instructs that “[a]n expert may base an opinion on facts or data in the case
5 that the expert has been made aware of or personally observed.” Dr. Lynch was given 6 information about Plaintiff’s job duties and also personally toured her workplace. Dkt. No. 21-1 7 ¶ 6. Plaintiff’s duties and environment impacted how likely she was to transmit COVID-19, and 8 to whom—considerations relevant to the cost of accommodating her—and Dr. Lynch’s 9 application of scientific information to these case-specific facts is sound methodology that will 10 help the finder of fact. See Fed. R. Evid. 702(d) (expert opinion must “reflect[] a reliable 11 application of the principles and methods to the facts of the case”). 12 The Court FINDS that Dr. Lynch’s opinions are reliable under FRE 702. 13 4. Plaintiff’s Other Arguments 14 Repeatedly, in support of her arguments on both relevance and reliability, Plaintiff argues
15 for exclusion based not on opinions Dr. Lynch has offered but opinions he has not offered, 16 mostly related to Plaintiff’s preferred framing of “the key issue” in this case. Dkt. No. 20 at 10 17 (opinions unhelpful because they “fail[] to speak to the key issue: how could masking and testing 18 be safe and effective from October to February and then unsafe or ineffective starting February 19 16, 2022”); see also id. at 3 (no opinion on how “it was safe to accommodate Ms. Dixson . . . 20 from October 18, 2021 to February 16, 2022, but not thereafter”); id. at 5 (no opinion on “why 21 . . . from October to February” Plaintiff’s accommodations were “not a risk”) id. at 14 (“no 22 method or analysis regarding the change from October 2021 to February 2022”); id. at 15 (no 23 opinion on “how [Defendant] accommodated, presumably safely, Ms. Dixson during this time,
24 but could not following the preset February 16, 2022 date”). Plaintiff also faults Dr. Lynch for 1 not being able to precisely quantify “the residual risk of acquisition and transmission” by an 2 unvaccinated person with Plaintiff’s accommodations (id. at 12; see also id. at 10–11, 13, 15) 3 and not opining on the actual incidence of breakthrough infections among Defendant’s 4 employees (id. at 14) or Defendant’s reliance on recommendations by the Centers for Disease
5 Control and Prevention (id. at 21). 6 Assuming for the sake of argument that these “missing” opinions are relevant and 7 otherwise admissible, their absence is a subject for cross-examination, not a basis for exclusion 8 of Dr. Lynch’s testimony under FRE 702. Any argument about what Dr. Lynch does not consider 9 or address goes to the weight and credibility of his conclusions. See Elec. Mirror, 2018 WL 10 5785385, at *1; see also Thomas v. YRC Inc., No. C16-6105, 2018 WL 919998, at *7 (S.D.N.Y. 11 Feb. 14, 2018) (“Courts have long recognized that the existence of alternative factual scenarios 12 that an expert has not considered in rendering an opinion goes only to the weight and credibility 13 of the expert’s testimony, not its admissibility.”). As such, to exclude Dr. Lynch’s testimony on 14 the basis Plaintiff suggests would be to exceed the Court’s authority in its gatekeeping role. See
15 Alaska Rent-A-Car, 738 F.3d at 969 (“Basically, the judge is supposed to screen the jury from 16 unreliable nonsense opinions, but not exclude opinions merely because they are impeachable.”). 17 The Court finds that Dr. Lynch is a qualified expert who has offered relevant, reliable 18 opinions that will assist in the resolution of Defendant’s undue hardship defense. Accordingly, 19 Plaintiff’s request to exclude Dr. Lynch’s opinions under Rule 702 is DENIED. 20 B. Rule 403 Challenge 21 Evidence will be excluded under FRE 403 only when its probative value is substantially 22 outweighed by such unwanted dangers as unfair prejudice or misleading the jury. “Unfair 23 prejudice” means “the possibility that the evidence will excite the jury to make a decision on the
24 basis of a factor unrelated to the issues properly before it.” Heyne v. Caruso, 69 F.3d 1475, 1481 1 (9th Cir. 1995) (quoting Mullen v. Princess Anne Volunteer Fire Co., 853 F.2d 1130, 1134 (4th 2 Cir. 1988)). Here, Plaintiff cites confusion of the issues, misleading the jury, and unfair prejudice 3 as reasons to exclude Dr. Lynch’s testimony under FRE 403. Dkt. No. 20 at 10, 12, 16. 4 The Court addresses each topic of testimony challenged under FRE 403 in turn.
5 5. Testimony on Vaccine Development and Approval 6 Plaintiff objects to Dr. Lynch testifying about the development and Federal Drug 7 Administration (“FDA”) approval of vaccines on the grounds that such testimony is both 8 irrelevant and prejudicial, contending that “[t]he introduction of these facts is more likely to 9 prejudice the trier of fact by implying that [Plaintiff] contests vaccines and FDA approval and/or 10 importance or efficacy. (FRE 403) This is simply not true and the inclusion is prejudicial.” Dkt. 11 No. 20 at 10; see also id. at 12 (“The report itself will result in ‘confusion of the issues’ under 12 FRE 403. It contains many paragraphs discussing the origins, progression, and supposed benefits 13 of COVID vaccination, which have nothing to do with the issues involved in this case, does not 14 help a trier of fact, and therefore, is not relevant.” 6). As to the relevance of these issues, the
15 Court agrees with Defendant that “[t]his data provides relevant background information about 16 options available to the City and others to control the spread of COVID-19 in the workplace in 17 late 2021 and early 2022.” Dkt. No. 28 at 13. As to any potential undue prejudice, Plaintiff 18 explains neither how facts about vaccine history and development imply anything at all about 19 Plaintiff’s personal opinions, nor how such an implication could be prejudicial when the very 20 basis of this case arises out of Plaintiff’s religious objection to a workplace vaccination 21 requirement. By contrast, Plaintiff’s own sworn declaration, filed in support of her opposition to 22 summary judgment, takes the unequivocal position that “vaccines . . . contain all kinds of 23 6 As the Court is not considering the admissibility of potential trial exhibits at this stage, but only whether experts may testify as to their opinions, Plaintiffs’ arguments about the admissibility of Dr. Lynch’s report are disregarded 24 as premature. 1 poisons and are derived from aborted fetal cells and corrupt my blood.” Dkt. No. 26 (Rosa Decl.) 2 at 4. Even had Plaintiff presented an otherwise colorable argument, the Court could not fairly 3 exclude Defendant’s evidence for merely implying what Plaintiff herself declares in no uncertain 4 terms.
5 Equally undeveloped is Plaintiff’s argument that “discussing the origins, progressions, 6 and supposed benefits of COVID vaccination” is “inflammatory” or tends to “‘suggest decisions 7 on an improper basis’” because “the pandemic is a sensitive topic through which everyone 8 suffered.” Dkt. No. 20 at 12 (quoting Hankey, 203 F.3d at 1172). The COVID-19 pandemic is 9 part of the fiber of this case, and Plaintiff has not shown either (a) that Dr. Lynch’s vaccine- 10 related testimony is more likely to provoke an emotional response than any other evidence that 11 will be presented or (b) that any emotions evoked by the testimony would lead jurors to any 12 particular conclusion on any issue in the case. 13 Accordingly, the Court DENIES Plaintiff’s request to exclude Dr. Lynch’s testimony 14 related to COVID-19 vaccine development and approval under FRE 403.
15 6. Opinions on Vaccine Hesitancy and Misinformation 16 Plaintiff also objects to a section of Dr. Lynch’s report entitled “Vaccine Hesitancy and 17 Misinformation,” on the grounds that it “is likely to be more prejudicial than beneficial to the 18 inquiry.” Dkt. No. 20 at 16. Besides this assertion, however, Plaintiff offers no argument on this 19 topic.7 “A mere recitation of an element or condition listed in Rule 403 is not an argument.” 20 Innovative Sports Mgmt. Inc. v. Hunt, No. C19-152, 2020 WL 5435312, at *2 (D. Ariz. May 12, 21 2020). This alone is a sufficient basis to reject Plaintiff’s unreasoned request for exclusion. 22
23 7 The remaining sentence in this paragraph has no apparent connection to the 403 analysis. See Dkt. No. 20 at 16. Instead, Plaintiff appears to again challenge the reliability of Dr. Lynch’s opinion regarding the relative risk of a 24 vaccinated or unvaccinated person. See supra Section III.A.3. 1 The Court notes, moreover, that most of the opinions Dr. Lynch offers in the challenged 2 section are directly responsive either to specific statements in Plaintiff’s complaint or to 3 arguments advanced by Plaintiff during this litigation. For example, Dr. Lynch acknowledges 4 that “[b]ecause vaccinated persons can become infected, that has led some people to mistakenly
5 believe that there is no difference between vaccinated and unvaccinated persons in terms of their 6 viral loads and/or infection rates,” and explains the science illustrating why this belief is 7 incorrect. Dkt. No. 21-1 ¶ 73. Plaintiff, through counsel, has put this subject at issue by, for 8 example, asserting that Plaintiff posed “no risk or de minimis cost from October to February” 9 and was in fact “the individual with the lowest risk rate” in Defendant’s employ. Dkt. No. 24 10 (Response to Motion for Summary Judgment) at 17, 21. Relatedly, Plaintiff urges that Defendant 11 should have based its accommodation decision on observations of Plaintiff and her coworkers 12 during the period of her temporary accommodation. E.g. id. at 17. In response, Dr. Lynch 13 explains why a “personal observation that vaccinated individuals got COVID-19 is irrelevant” 14 and misleading, and why an employer cannot “rely on what it observes in its workplace
15 regarding COVID-19 positive cases and vaccination status to guide its assessment of COVID-19 16 risks and ways to reduce them.” Dkt. No. 21-1 ¶¶ 79, 80. The Court will not exclude these 17 opinions on the ground that they may help Defendant’s case. “Of course, all relevant evidence is 18 prejudicial; Rule 403 is concerned only with limiting ‘unfair’ prejudice.” United States v. Castro, 19 No. CR19-295, 2023 WL 2786830, at *3 (D. Nev. Apr. 5, 2023) (quoting United States v. 20 Simpson, 910 F.2d 154, 158 (4th Cir. 1990)). Plaintiff has not shown that allowing these opinions 21 would be unfair, and indeed, it is more likely that Defendant would be unfairly prejudiced by 22 their exclusion, which would hamper its ability to make its case in light of Plaintiff’s arguments. 23 In addition, as “many people have been exposed to health misinformation,” these opinions may
24 be helpful to jurors for whom such “misinformation has caused confusion.” Dkt. No. 21-1 ¶ 71. 1 Cf. United States v. Common, 818 F.3d 323, 330 (7th Cir. 2016) (fingerprint expert’s “testimony 2 was relevant to helping jurors overcome” a “common misconception”). 3 Accordingly, the Court DENIES Plaintiff’s request to exclude the opinions in the section of 4 Dr. Lynch’s report titled “Vaccine Hesitancy and Misinformation.”
5 7. Purported Opinion Regarding Temporary Accommodation 6 Finally, Plaintiff argues that Dr. Lynch’s purported opinion that Defendant should not 7 have accommodated Plaintiff even temporarily “will likely confuse the trier of fact[,] not assist 8 [them].” Dkt. No. 20 at 10 (brackets8 in original). The Court need not consider the likelihood of 9 confusion because Plaintiff presents no evidence that Dr. Lynch has ever expressed this opinion. 10 The deposition testimony cited by Plaintiff does not support her assertion that Dr. Lynch 11 “disagreed with the entirety of COI’s decision to accommodate” Plaintiff and, in fact, suggests 12 that Dr. Lynch took care during his deposition not to opine on Defendant’s temporary 13 accommodation decisions. Id. (citing 22-1 (Lynch Dep.) at 52–54 (88:14–24, 91:21–92:06)). For 14 example:
15 Q. Do you think that the city should have implemented testing every day? 16 A. I think that the city should have–let me put this another way. I think she should 17 have gotten vaccinated. 18 Dkt. No. 22-1 at 52. The other testimony cited by Plaintiff arose from a question about why 19 Defendant would have accommodated her; Dr. Lynch responded that he was neither a human 20 resources person nor involved in the conversations. Id. at 55–56. Dr. Lynch tried to discern the 21 rationale by reading the documents with which he was presented and responded that 22 accommodating Plaintiff was a policy decision by human resources. Id. Nowhere in the 23 referenced material did he opine that Defendant should not have accommodated Plaintiff. These
24 8 The meaning of these brackets is unclear. See supra n.4. 1 exchanges, viewed along with their mischaracterization here by Plaintiff’s counsel (who also 2 deposed Dr. Lynch), create the impression that counsel, not having solicited the deposition 3 testimony she wanted from Dr. Lynch, decided to distort his testimony beyond recognition. The 4 Court will give counsel the benefit of the doubt and assume that this was an honest mistake
5 rather than a willful misrepresentation. Counsel is advised, however, that this is just one of 6 several instances in which counsel has distorted or misrepresented deposition testimony.9 7 Counsel should take more care in the future or run the risk of sanctions under Federal Rule of 8 Civil Procedure 11. See, e.g., Patterson v. Apple Comput., Inc., No. C04-405, 2005 WL 9 2277005, at *37 (N.D. Cal. Sep. 19, 2005) (levying Rule 11 sanctions based, in part, on 10 counsel’s misrepresentation of deposition testimony), aff’d, 256 F. App’x 165 (9th Cir. 2007). 11 For the foregoing reasons, Plaintiff’s request to exclude Dr. Lynch’s opinions as 12 prejudicial or misleading under FRE 403 is DENIED. 13 IV. CONCLUSION 14 Accordingly, Plaintiff’s motion to exclude the opinions of Defendant’s expert (Dkt.
15 No. 20) is DENIED. 16 Dated this 15th day of September, 2025. A 17 Tana Lin 18 United States District Judge
19 20 9 See also, e.g., Dkt. No. 24 at 23 (Here, counsel cites to deposition testimony by Chief Paula Schwann in support of 21 a statement that “The N95 masks never ran out of supply.” But Schwann was actually asked if tests ever ran out and replied, “I don’t recall us ever running out. . . . So I don’t believe so but I don’t—I don’t completely recall.” Dkt. 22 No. 25-1 at 49–50.); Dkt. No. 24 at 10 (“Sgt. Huberdeau stated it was not a hardship of time to administer the tests because he could multi-task.” In the deposition excerpt cited in support, Sgt. Dustin Huberdeau was not asked about hardship but about whether the testing “affect[ed his] efficiency on shift,” and replied “I don’t—that’s kind of a 23 difficult question. I—I don’t know if it was—I mean, it took 20 minutes of my day at the beginning of my day, yes. But efficiency, I would like to say no, because I was able to multitask during that 15 minutes and do other things.” 24 Dkt. No. 25-5 at 12.).