Zantac Federal MDL Dismissal — What Happened

What Was the Federal Zantac MDL?

A multidistrict litigation (MDL) is a federal procedural device that consolidates cases involving similar claims and common factual questions from multiple federal courts into one court for coordinated pretrial proceedings. In re: Zantac (Ranitidine) Products Liability Litigation (MDL No. 2924) was consolidated in the U.S. District Court for the Southern District of Florida before the Honorable Robin L. Rosenberg. At its peak, the MDL included tens of thousands of cases from plaintiffs across the country who alleged that Zantac caused their cancer. The MDL was established to manage the vast volume of litigation efficiently and to resolve common legal and scientific questions — particularly the threshold question of general causation — on behalf of all plaintiffs in the federal system.

The Daubert Ruling — November 2022

The central legal battle in the Zantac MDL was the admissibility of plaintiffs' general causation expert witnesses — the scientists and physicians whose testimony was intended to establish that ranitidine can cause cancer in humans. In November 2022, Judge Rosenberg issued a comprehensive Daubert ruling that excluded all of plaintiffs' general causation experts for multiple cancer types. The court found that the methodologies used by plaintiffs' experts were scientifically unreliable under the standards set by Daubert v. Merrell Dow Pharmaceuticals (1993) and its federal progeny. Specific criticisms included: (1) reliance on epidemiological studies with fundamental methodological flaws; (2) improper extrapolation from animal studies to human cancer risk; (3) use of unpublished and non-peer-reviewed analyses; and (4) failure to adequately account for confounding variables in population studies. Without admissible general causation experts, plaintiffs could not establish that ranitidine causes cancer at all, let alone in their specific cases. Summary judgment for defendants was therefore granted on all claims in the MDL.

What the MDL Dismissal Does NOT Mean

The November 2022 federal MDL dismissal is frequently misunderstood — and sometimes misrepresented — as establishing that Zantac does not cause cancer, or that all Zantac litigation is over. Neither is correct. The ruling is a federal procedural determination about whether specific expert witnesses, using specific methodologies, satisfied the requirements of the Federal Rules of Evidence in a specific federal court. It has no legal effect on state court claims, which are governed by state procedural rules and state evidentiary standards. State courts are not bound by Judge Rosenberg's rulings, the Federal Rules of Evidence, or the Daubert standard. The Eleventh Circuit's affirmance and the Supreme Court's denial of certiorari likewise apply only to the federal proceedings.

State Courts Apply Different Standards — Why Claims Continue

State courts apply their own evidentiary frameworks for expert testimony. Delaware uses the Frye standard (general acceptance in the relevant scientific community), California uses the Kelly/Frye standard, and most other states use either Daubert or state-specific variations. Under Frye, the question is not whether the individual expert's specific methodology is reliable in the Daubert sense, but whether the scientific community generally accepts the methodology. Plaintiffs' attorneys have also updated and strengthened their expert presentations since the federal MDL, specifically addressing the methodological criticisms raised by Judge Rosenberg and commissioning new peer-reviewed epidemiological analyses. Delaware state court has proceeded to schedule bellwether trials. California courts have denied summary judgment motions in multiple cases. The science has not stopped developing, and the litigation has not ended — it has relocated.