General-causation epidemiologist
Expert class library · Mass tort and product liability · Plaintiff side
Reviews the body of epidemiologic studies to opine whether an exposure is capable of causing a disease in the general population. Weighs the evidence under the Bradford Hill considerations.
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Questions this testimony turns on
- Is the exposure capable of causing the disease in the general population?
- Is the observed association real, or explained by chance, bias, or confounding?
- How do the Bradford Hill considerations weigh across the full body of evidence?
- What do meta-analyses and the strongest studies show about strength and consistency of association?
Methods
- Bradford Hill causation analysis
- Weight-of-the-evidence review
- Meta-analysis
- Assessment of bias and confounding
- Relative risk interpretation
How the testimony is attacked
- Unreliable application of Bradford Hill. Courts accept Bradford Hill as a method but require the expert to explain how each factor was assessed and weighed. Zoloft and Onglyza both affirmed exclusions on this ground.
- Cherry-picking. Selecting favorable studies or comparators undermines the weight-of-the-evidence approach. In Onglyza the expert used a different drug class for the analogy factor instead of the drug's own class.
- Overreliance on a single study. Building a causation opinion on one trial while discounting later human data is a recurring ground for exclusion, as in Onglyza.
- Inconsistent treatment of statistical significance. Applying different techniques to different data subsets, or discussing significance selectively, signals a result-driven analysis. Zoloft relied on this in affirming exclusion.
- Opinions outside the expert's field. Interpreting animal or clinical findings beyond one's training invites exclusion. Onglyza noted the expert conceded he was not qualified to make the animal diagnoses he relied on.
- Close calls still admitted. Where the expert integrates epidemiology, toxicology, and mechanism evidence with a disclosed method, courts may admit even contested opinions. Hardeman affirmed admission despite the trial court calling it a very close question.
What the public record shows
Courts have filed at least 49 opinions since 2015 that discuss this class of testimony and cite Daubert or Rule 702, as of October 4, 2026. 7 rulings that show how courts handle this class of testimony:
| Outcome | Case | Court | Year | Why |
|---|---|---|---|---|
| Exclusion reversed | Rutledge v. Walgreen Co.No. 24-916 | 2d Cir. | 2026 | The Second Circuit vacated the exclusion of three general causation experts who linked prenatal acetaminophen to ADHD and autism, holding the district court substituted its own reading of epidemiological criteria for the experts' and faulted them for conclusions on which the scientific community disagrees, and held their testimony admissible. |
| Excluded | In re Zantac (Ranitidine) LitigationNo. 255, 2024 | Del. | 2025 | The Delaware Supreme Court reversed the denial of motions to exclude the plaintiffs' general causation experts in the ranitidine litigation, holding that the proponent must establish reliability by a preponderance, that challenges cannot be passed to the jury as weight, and that studies of the toxic agent need a reliable bridge to exposure from the product itself. |
| Excluded | In re Onglyza (Saxagliptin) and Kombiglyze (Saxagliptin and Metformin) Prods. Liability Litig.93 F.4th 339 | 6th Cir. | 2024 | The Sixth Circuit affirmed exclusion of the plaintiffs' general-causation expert, who leaned on a single trial, used animal data outside his expertise, cherry-picked the analogy factor, and shifted his positions on Bradford Hill factors without explanation. |
| Admitted | Hardeman v. Monsanto Co.997 F.3d 941 | 9th Cir. | 2021 | The Ninth Circuit affirmed admission of the plaintiff's general-causation experts, who combined epidemiology, animal and cell studies, Bradford Hill, and meta-analyses, even though the trial court found admissibility a very close question. |
| Exclusion reversed | Amador v. 3M Co.No. 19-2899 | 8th Cir. | 2021 | The Eighth Circuit held that the MDL court abused its discretion by excluding general causation experts who linked a forced-air warming device to surgical infections for analytical gaps, noting they relied on epidemiological evidence and that the weaknesses identified bore more on specific causation. |
| Admitted | In re Abilify (Aripiprazole) Products Liability Litigation299 F. Supp. 3d 1291 | N.D. Fla. | 2018 | After a four-day hearing, the MDL court admitted the plaintiffs' general causation opinions that an antipsychotic can cause compulsive gambling and other impulse-control behaviors, finding their epidemiology, dose-response evidence and Bradford Hill and weight-of-the-evidence analyses reliable, and denied summary judgment. |
| Excluded | In Re Zoloft (Sertraline Hydrochloride) Products Liability Litigation858 F.3d 787 | 3d Cir. | 2017 | The Third Circuit affirmed exclusion of the plaintiffs' causation expert, holding that although Bradford Hill and weight-of-the-evidence methods are reliable, he applied his techniques inconsistently and did not explain how he reached conclusions on strength and consistency of association. |
Each case links to the free opinion text on CourtListener.
In federal court: amended Rule 702
In federal court, since December 1, 2023, Rule 702 says expressly that the party offering an expert must show the court it is more likely than not that the testimony meets each requirement: that it rests on sufficient facts or data, uses reliable methods, and reflects a reliable application of those methods to the case. Questions about the basis of an opinion are no longer automatically matters of weight for the jury. For how the circuits have applied the amendment, see the Rule 702 tracker, which follows each court of appeals; for what that means for preparing or attacking this class of expert, see the guide on amended Rule 702.
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Updated October 4, 2026. How this page is built: rulings are found by searching court opinions on CourtListener. The summaries are written by AI working from the full text of each opinion, and every citation and link is checked automatically. Outcomes are labelled by what the court did with the expert’s testimony. No individual expert is named. This page summarises public decisions for orientation and is not legal advice; read the opinion before relying on any ruling. Spotted an error? Tell us.