Talc Multidistrict Litigation Tests Judges’ Gatekeeping Role

The ongoing multidistrict litigation involving talc—the largest mass tort in the US—presents a critical test of whether the federal judiciary is meaningfully absorbing an amendment to Federal Rule of Evidence 702.

Rule 702 was amended in December 2023 by the Judicial Conference Advisory Committee on Evidence Rules to reinforce a principle that should have been clear for decades: Trial judges are gatekeepers who are required to determine, under Rule 104(a), that expert testimony satisfies every admissibility requirement by a preponderance of the evidence.

The amendment didn’t change Rule 702’s substance. It sought to correct persistent misapplications, including the tendency of some courts to treat reliability disputes as matters of “weight” for the jury rather than thresholds for admissibility that are determined by the judge.

In January, a Special Master appointed by the US District Court for the District of New Jersey issued a lengthy report and recommendation on general-causation expert testimony regarding whether perineal use of talcum powder can cause ovarian cancer.

The Special Master’s report recites Rule 702’s amended language and invokes the preponderance standard. Yet its analysis raises a familiar concern: Are courts still too quick to resolve challenges to dubious methodology by simply admitting the testimony and leaving it to the jury to sort out?

The central issue in the talc litigation is whether the plaintiff’s claim of causation is based on sufficient facts and data, and whether the plaintiffs’ experts conclusion regarding causation reflects a reliable application of the principles and methodology they are using.

The plaintiffs cite evidence of some epidemiologic association between talc and ovaran cancer, but defendants argue that the epidemiologic record is modest, contested, and subject to multiple sources of bias. Moreover, evidence on issues such as dose-response and exposure quantification remains limited, and is insufficient to reliably support the allegation that defendants’ product is responsible for the plaintffs’ injuries.

Instead of requiring the plaintiffs’ experts justify their methodological choices and explain how they reliably filled in the gaps in the data, the report excused their testimony’s infirmities. The report concluded that under a “weight-of-the-evidence” approach, the testimony as a whole was sufficiently reliable to be admissible.

Rule 702 requires more than a demonstration that an expert has invoked a recognized methodology such as the Bradford Hill criteria. Instead, the court must determine that the methodology has been applied reliably to the facts of the case and that the resulting opinion doesn’t outrun its evidentiary foundation.

When a methodology places substantial emphasis on factors such as strength, consistency, and dose response, a court must decide whether the available evidence is sufficient—by a preponderance—to support the expert’s causal conclusion. That determination belongs to the judge under Rule 104(a), and only goes to the jury through if the judge has determined that it passes the rigorous test enunciated in Rule 702.

Similar concerns arise about testimony on biological plausibility. No study has shown that externally applied talc migrates through the reproductive tract. Yet plaintiffs are permitted to rely on analogies, animal studies with inconsistent findings, and laboratory conditions that don’t reflect consumer use.

The report concludes that plaintiffs’ experts rely on a broader body of literature supporting plausibility and therefore may present that theory. But plausibility alone isn’t causation.

Rule 702 requires a reliable bridge between mechanistic hypotheses, real-world exposure, and disease risk. Where that bridge depends on contested inferences about exposure levels, particle movement, and carcinogenic effect, the court must decide whether the chain of reasoning satisfies the rule’s reliability requirements or instead rests on gaps that should preclude the ultimate opinion.

By accepting possibility as equivalent to plausibility—and plausibility as sufficient for admissibility—the report lowers the evidentiary bar and opens the door to speculative theories. Rule 702 requires that expert opinions be tethered to evidence, not mere hypotheses.

More fundamentally, the ruling risks abdicating the judicial gatekeeping function in favor of jury determination.

Instead of assessing whether expert testimony is based on reliable methods and application—a core responsibility under Rule 702—the report routinely treats methodological deficiencies (such as inconsistent epidemiology, recall bias, and speculative biological mechanisms) as issues of “weight” for the jury.

That approach surrenders the court’s role in filtering out unreliable science, exposing jurors (who lack specialized training) to disputes they are ill-equipped to resolve without a preliminary ruling by a judge that the underlying science is sound.

These concerns aren’t abstract, and the implications of the District of New Jersey’s pending ruling based on the report extend far beyond this case. By treating methodological reliability as a jury question and allowing experts to bypass meaningful judicial scrutiny, the ruling could turn federal courts into arenas for narrative persuasion rather than scientific adjudication.

If accepted by District Court, the report will erode the foundational safeguards that Rule 702 was designed to strengthen.

None of this means courts must demand scientific unanimity or resolve every genuine dispute among qualified experts. But the amended Rule 702 underscores that admissibility isn’t a default position. The party proffering expert testimony bears the burden of proving, by a preponderance of the evidence, that each element of the rule is met.

When judges recite Rule 702 faithfully but resolve substantial question of data sufficiency and methodological reliability by surrendering the issues to the jury , they risk turning the rule into a formality rather than a gatekeeping standard. The 2023 amendment was meant to prevent exactly that outcome.

This article does not necessarily reflect the opinion of Bloomberg Industry Group, Inc., the publisher of Bloomberg Law, Bloomberg Tax, and Bloomberg Government, or its owners.

Author Information

David E. Bernstein is law professor and executive director of the Liberty and Law Center at George Mason Antonin Scalia School of Law.

Write for Us: Author Guidelines