Under Daubert v. Merrell Dow and Federal Rule of Evidence 702, judges gatekeep expert testimony for reliability: testable methods, peer review, error rates, general acceptance. In mass torts, general-causation experts — the scientists linking product to disease — are the whole ballgame.
The cautionary tale is Zantac: in 2022 the MDL judge excluded plaintiffs' causation experts, effectively ending roughly 50,000 federal claims overnight. Firms that had borrowed against those inventories absorbed the loss — a reminder that scientific posture is claim value.
Sources & attribution