Epidemiology Expert’s Testimony Consisted of Unreliable Recitations of Scientific Studies
Posted on August 20, 2025 by Expert Witness Profiler
Plaintiff Leroy Jerome Richardson, III, a basketball referee, has sued his former employer, NBA Services Corp. and the National Basketball Association (together, the “NBA”) after his request for a religious exemption from its requirement that all NBA referees be vaccinated against COVID-19 during the 2021-22 season was denied.
The NBA filed a motion to exclude the testimony of the Plaintiff’s expert, Dr. Harvey Risch.
Epidemiology Expert Witness
Harvey A. Risch is a practicing epidemiologist with more than 40 years of research and teaching experience. He is a Professor Emeritus of Epidemiology at Yale School of Public Health.
The majority of his career has focused on cancer and its causation. In May 2020, he published a paper on early treatment of high-risk COVID-19 outpatients. Since that time, he has co-authored other papers on COVID-19, which he describes as focusing on early outpatient management.
Discussion by the Court
Risch believes that the spread of infection is inevitable and post-infection natural immunity is a public good. He believes that the pandemic should not have been managed by tracking infection but rather by tracking deaths, hospitalization, and the incidence of serious long-term syndromes caused by infection. Accordingly, he asserts, governments, businesses and schools should not have mandated vaccination to prevent the spread of infection.
Insofar as the NBA is concerned, Risch observed that by December 2021, the NBA had added a booster dose requirement to its mandate. Nonetheless, NBA referees and players, almost all of whom were vaccinated, caught COVID-19 during the 2021-22 season. Risch concluded that, given the small number of NBA staff seeking a religious exemption, even if all had gotten COVID-19, the infection burden would have been less than the breakthrough infection burden among the vaccinated referees.
Relevance
The NBA argued that many of Risch’s opinions are irrelevant. According to the NBA, the issue for the jury will be whether it reasonably relied on health authority guidance for the 2021-22 season and has carried its burden to show that allowing exemptions to its vaccination policy would have imposed an undue hardship. Accordingly, the NBA sought to strike Risch’s disagreements with the advice given by government agencies regarding COVID-19 and the data presented by government health authorities. For instance, Risch took issue with whether the government data was accurate and argued that the government should have focused more on issues such as post-infection natural immunity or developed incentives for vaccination.
Although Risch is offered as a witness on the issue of undue hardship, he did not offer any opinion on the negative impact that game postponement, rescheduling, and cancellation would have on the NBA and those involved in NBA games. Nor did he dispute that the Omicron variant of the COVID-19 virus was considered even more transmittable than prior variants. His disagreements with public health management of the pandemic are irrelevant to the particular issues that created hardship for the NBA and the reasonableness of the NBA’s reliance on its experts in 2021 and 2022.
The NBA sought to strike as well those opinions which relied on studies published after the 2021-22 season as irrelevant to the NBA’s determination by December 2021 to insist that its referees be vaccinated.
Although Risch indicated that he is relying on later studies only to confirm his opinion, without those later studies it is unclear whether Risch had any reliable basis in the fall of 2021 for a different opinion than the one offered by the NBA’s medical consultants. The Court held that citing those later studies would only create confusion at best.
Legal Conclusion
The NBA additionally sought to exclude Risch’s report to the extent it offered legal conclusions. As an example of such inadmissible testimony, the NBA pointed to Risch’s opinion that allowing Richardson to work without a vaccination did not constitute an undue hardship when measured against the Equal Employment Opportunity Commission (“EEOC”) guidelines.
The NBA is correct that the Plaintiff’s expert cannot offer such opinions to the jury. In opposition to this motion, Richardson agreed that Risch cannot testify to the legal conclusions in his report.
Reliability
The NBA explained that Risch has rejected nearly all of the studies that were available during the 2021-22 season and has relied instead on a 2024 “pre-print” study — i.e., a study that is shared publicly but not peer-reviewed — to conclude that vaccinations were not as effective as they were believed to be through 2022.
The NBA also contended that Risch has selectively pointed to passages in studies to reach conclusions different from what the authors of the study concluded, and has done so without an adequate explanation.
In opposing this motion, Richardson pointed to only three studies that he argued are relevant and provide appropriate support for Risch’s opinion: Madewell, Puhach and the pre-print Riemersma.
While Madewell acknowledged that COVID-19 vaccines became less effective in reducing the spread of new variants, Risch distorted Madewell to cite it for the proposition that vaccines had “lost most of their ability” to suppress the spread of infection. Puhach was not published until March 2023 and therefore would not have been available to the NBA when it made its decision to no longer permit unvaccinated referees to work.
Finally, Riemersma, according to Risch, indicated that those infected during the period in which the Delta variant was prominent, had “similar” viral loads whether or not they had been vaccinated. That is an accurate description of Riemersma. But this study, which was not peer reviewed, does not undercut the advice the NBA’s experts provided to it, much less the recommendations of the Centers for Disease Control and Prevention (“CDC”). It does not take issue with the data showing that vaccination reduced the risk of infection.
In sum, the Court ruled that Risch’s opinions should also be excluded because they were not reliable.
Rule 403
Finally, the NBA argued that the report must also be stricken pursuant to Rule 403.
Risch’s analysis created a substantial risk of confusing and misleading the factfinder. In deciding whether the NBA has carried its burden of showing that an accommodation of Richardson would have created an undue hardship, jurors must focus on what the relevant scientific community and the NBA understood of the COVID-19 virus and the efficacy of vaccines and testing in the 2021-22 season, particularly during the late fall of 2021.
The Court held that Risch’s criticism of public health authorities’ recommendations in the midst of a pandemic, especially when based on a few hand-picked studies that post-date the period in which the NBA made its decision, has limited to no probative value.
Held
The Court granted the Defendants’ motion to exclude the testimony of the Plaintiff’s expert, Dr. Harvey Risch.
Key Takeaway:
While cross-examination is an appropriate method for demonstrating the limitations in an expert’s analysis, before that analysis may be admitted at trial, its proponent must still show that it is sufficiently reliable to pass muster under Rule 702 and Daubert. This Richardson has not done.
Admission of Risch’s testimony risks misleading and confusing the jury as to the relevant standard for determining undue hardship and the relevant evidence on which to base its verdict.
Case Details:
| Case Caption: | Richardson V. The National Basketball Association Et Al |
| Docket Number: | 1:23cv6926 |
| Court Name: | United States District Court, New York Southern |
| Order Date: | August 18, 2025 |
