--- title: "Infectious Disease Expert Was Allowed to Opine on Masking and Testing" meta: "og:description": "The infectious disease expert was permitted to testify because his opinions stem from decades of clinical experience" "og:title": "Infectious Disease Expert Was Allowed to Opine on Masking and Testing" author: "Expert Witness Profiler" description: "The infectious disease expert was permitted to testify because his opinions stem from decades of clinical experience" --- # Infectious Disease Expert Was Allowed to Opine on Masking and Testing Posted on December 9, 2025 by Expert Witness Profiler Eight former Redmond firefighters sued the City of Redmond (“City”) after being terminated for refusing COVID-19 vaccinations on religious grounds. They argued the City should have let them continue working with masking and testing rather than requiring vaccination. Plaintiffs filed a _[Daubert](https://www.law.cornell.edu/wex/daubert_standard)_ motion to exclude the testimony of the City’s expert, Dr. [John Lynch](https://expertwitnessprofiler.com/expert-witness/John-Lynch/1567383). ## **Infectious Disease Expert Witness** Dr. [John B. Lynch](https://expertwitnessprofiler.com/expert-witness/John-Lynch/1567383) is a board-certified physician in infectious disease, Professor of Medicine at the University of Washington, and Associate Medical Director of Harborview Medical Center. Moreover, he led UW Medicine’s COVID-19 Emergency Operations Center from February 2020 through December 2023, overseeing PPE and testing policies, and has authored 82 peer-reviewed publications, including 15 on COVID-19. [Get the full story on challenges to John Lynch’s expert opinions and testimony with an in-depth Challenge Study](https://expertwitnessprofiler.com/order/add?eId=1567383&pId=3). ## **Discussion by the Court** Plaintiffs challenged Lynch’s qualifications, arguing that he lacks expertise in masking and testing, that his opinions were irrelevant because Defendant allegedly lacked an undue hardship defense, and that his method is unreliable because he did not conduct original research. The Court disagreed. Basically, medical experts commonly base their opinions on clinical experience, peer-reviewed literature, and public health guidance—precisely the materials Lynch relied on here. Moreover, Lynch’s opinions are grounded in decades of clinical experience, extensive review of scientific literature, and his direct involvement in the public health response to COVID-19. ## **Held** The Court denied the Plaintiffs’ motion to exclude the testimony of Defendant’s expert Dr. John Lynch. ## **Key Takeaway** The Ninth Circuit has explained that expert testimony is reliable if the knowledge underlying it has a reliable basis in the knowledge and experience of the relevant discipline. If Plaintiffs wish to challenge what Lynch failed to consider or address, such critiques go to weight and credibility—subjects for cross-examination—not admissibility. ## **Case Details:** --- ## **You Might Also Like** ![Human Resources Expert Allowed to Opine on Termination](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-22T200052.311.jpg) [**Human Resources Expert Allowed to Opine on Termination**](https://expertwitnessprofiler.com/infectious-disease-expert-was-allowed-to-opine-on-masking-and-testing/human-resources-expert-allowed-to-opine-on-termination)![Neuropsychology Expert Not Allowed to Opine on Cognitive Decline](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-22T144728.528.jpg) [**Neuropsychology Expert Not Allowed to Opine on Cognitive Decline **](https://expertwitnessprofiler.com/infectious-disease-expert-was-allowed-to-opine-on-masking-and-testing/neuropsychology-expert-not-allowed-to-opine-on-cognitive-decline)![Human Factors Expert Not Allowed to Opine on the Tile](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-21T191749.960.jpg) [**Human Factors Expert Not Allowed to Opine on the Tile**](https://expertwitnessprofiler.com/infectious-disease-expert-was-allowed-to-opine-on-masking-and-testing/human-factors-expert-not-allowed-to-opine-on-the-tile)![Insurance Expert Not Allowed to Opine on Legal Duties](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-21T155751.487.jpg) [**Insurance Expert Not Allowed to Opine on Legal Duties**](https://expertwitnessprofiler.com/infectious-disease-expert-was-allowed-to-opine-on-masking-and-testing/insurance-expert-not-allowed-to-opine-on-legal-duties)![Law And Legal Expert Not Allowed to Opine on Contract Formation](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-20T213123.718.jpg) [**Law And Legal Expert Not Allowed to Opine on Contract Formation**](https://expertwitnessprofiler.com/infectious-disease-expert-was-allowed-to-opine-on-masking-and-testing/law-and-legal-expert-not-allowed-to-opine-on-contract-formation)