Product Liability & Mass Torts Digest

The Southern District of New York’s recent opinion in the In re Acetaminophen MDL establishes strong guardrails regarding how expert witnesses can rely on studies and data in support of their opinions. By way of background, In re Acetaminophen involves more than 600 plaintiffs who allege that the manufacturer and retailers of acetaminophen products failed to warn that children may develop autism spectrum disorder (ASD) or attention-deficit hyperactivity disorder (ADHD) from in utero exposure to the drug. In an opinion issued on December 18, 2023, Judge Denise Cote of the Southern District of New York excluded all five of the plaintiffs’ general causation experts as unreliable.

A Bradford Hill analysis—a set of criteria first proposed by the British epidemiologist Sir Austin Bradford Hill in 1965 to evaluate the strength of evidence for a causal relationship between two variables[1]—often plays a critical role in causation opinions of plaintiff experts in product liability matters. 

A recent and thorough opinion in In re Acetaminophen – ASD-ADHD Products Liability Litigation reaffirms the need for parties’ general causation experts to meaningfully engage with known confounding factors to ensure the admissibility of their opinions. 

In forming an admissible opinion about whether exposure to or use of a defendant’s product caused a plaintiff’s disease or condition, the plaintiff’s expert must factor into their differential diagnosis the role played by potential alternative causes. Yet in many instances, plaintiffs’ experts do not rule out unknown or unexplained causes—also known as idiopathic causes—even when idiopathy is the most likely explanation for the disease or condition.

The plaintiffs in the Zantac MDL faced a challenge that is common in products liability cases: How to handle evolving science and conflicting epidemiological data.

As part of our continuing commentary on the Zantac decision, this review examines the court’s rationale for doing so and highlights potential avenues for Daubert challenges to experts conducting Bradford Hill analyses.

The Zantac MDL Court recently reinforced the important role of general acceptance of an expert’s conclusions to a court’s Rule 702 admissibility analysis.

Earlier this month, 3M filed a petition for writ of certiorari requesting that the U.S. Supreme Court review an Eighth Circuit opinion reversing the district court and allowing expert testimony in a lawsuit involving 3M’s commonly used surgical warming blankets. In re Bair Hugger Forced Air Warming Devices Prod. Liab. Litig., 9 F.4th 768 (8th Cir. 2021).

Recently, in Ebert v. C.R. Bard, Inc., the Third Circuit considered two questions of medical-device liability left unresolved by Pennsylvania law. The first is whether a plaintiff claiming that a device was negligently designed must prove that the device was “too harmful to be used by anyone.” The second is whether a strict liability claim involving a medical device is cognizable under Pennsylvania law.

Last week, in In re Davol, Inc./C.R. Bard, Inc., Polypropylene Hernia Mesh Products Liability Litigation, the U.S. District Court for the Southern District of Ohio held that an expert may not opine on the intent or state of mind of a corporation and that a historical recounting of internal company documents is not permissible expert testimony.

Last month, the U.S. Court of Appeals for the Fifth Circuit affirmed two summary-judgment decisions in In re Taxotere (Docetaxel) Products Liability Litigation, a coordinated multidistrict litigation (MDL) that is centralized in the Eastern District of Louisiana.

In re: Zantac (Ranitidine) Product Liability Litigation is a coordinated multi-district litigation (MDL) centralized in the Southern District of Florida. The MDL involves allegations (which the defendants deny) that the active ingredient in Zantac (a heartburn medication) and its generic formulations are potentially carcinogenic because ranitidine can transform into the cancer-causing molecule NDMA.

Multidistrict Litigations (MDLs) often involve parties from different states litigating in a district court with no geographical tie to the claims or parties. As a result, complicated choice-of-law questions arise.

A key purpose of multidistrict litigation (MDL) is centralized management of pretrial proceedings to avoid duplicative discovery and resolve common issues in an efficient manner. An MDL court becomes sufficiently familiar with the facts, scientific issues, and procedural history of the litigation to often allow a just and efficient resolution of complex discovery disputes.