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 motion to exclude the testimony of the City’s expert, Dr. John Lynch.
Infectious Disease Expert Witness
Dr. John B. Lynch 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.
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:
| Case Caption: | Carlson V. City Of Redmond |
| Docket Number: | 2:22cv1739 |
| Court Name: | United States District Court, Washington Western |
| Order Date: | December 05, 2025 |
