Daubert Gatekeeping in Mass Tort Litigation

Daubert gatekeeping refers to the trial court's obligation under Federal Rule of Evidence 702 and the Supreme Court's decisions in Daubert v. Merrell Dow Pharmaceuticals (1993), General Electric Co. v. Joiner (1997), and Kumho Tire Co. v. Carmichael (1999) to screen expert testimony for reliability before it reaches a jury, assessing whether the expert's methodology is scientifically valid and reliably applied to the facts of the case. In mass tort MDLs, gatekeeping is typically exercised through a single, consolidated hearing addressing the admissibility of the plaintiffs' — and sometimes the defendants' — general causation experts, since the same expert opinions and methodology apply across every claim on the docket. A transferee judge's Daubert ruling is reviewed only for abuse of discretion on appeal, giving trial courts substantial latitude, and outcomes can range from full admission, to partial exclusion of specific opinions or methodologies, to wholesale exclusion that ends the docket. Because gatekeeping hearings often follow an earlier, non-evidentiary science day presentation, the transferee judge typically enters the Daubert phase with an informed view of the scientific dispute, and the eventual ruling is shaped as much by the judge's accumulated impression of the science as by the formal briefing on any single motion.

The Daubert ruling on general causation experts is the single highest-stakes event in most mass tort dockets, and funders treat it as a discrete, binary underwriting milestone rather than a gradual risk that resolves over time. Capital committed before a favorable ruling is priced at a steep discount to reflect exclusion risk, while capital deployed after admission is priced closer to settlement-stage risk.

Many docket financing structures explicitly stage disbursements around the Daubert ruling date, reserving the largest tranches for deployment only once the causation evidence has survived gatekeeping scrutiny.