FRE 702 Gatekeeping and Specific Causation in Toxic Torts: Admissibility of Differential Etiology Expert Testimony

This CLE webinar will discuss proving specific causation in mass tort and toxic tort cases, factors that affect whether differential etiology evidence and experts are admissible under Federal Rule of Evidence 702, and lessons and strategies for both plaintiffs and defendants from the settlement of In re Johnson& Johnson Talcum Powder Products Marketing, Sales Practices and Products Liability Litigation.

Even if a plaintiff can establish that exposure to a particular substance (e.g., PFAS, PCBs, talc, glyphosate, paraquat, opioids, vaccines, hair relaxers, ethylene oxide) is capable of causing a condition or disease (general causation), they must still establish that it, and not something else, more likely than not caused the plaintiff's injury. To begin with, a plaintiff must establish pre-injury exposure at levels sufficient to cause injury and that the onset of injury was consistent with what others experienced.  

The plaintiff must also consider and exclude alternative causes using expert testimony. The method by which experts perform differential etiology to rule in or rule out alternative causes is subject to increasing scrutiny under FRE 702. Differential etiology is particularly vulnerable to challenge when, as in the J&J litigation, the injury has multiple risk factors, and experts cannot reliably ascertain for a specific individual whether those risk factors acted cumulatively, additively, or synergistically. Moreover, the etiology for some injuries is simply unknown. 

Plaintiff and defense commentators seem to agree that specific causation evidence and experts have to be developed and tested early and often from the very beginning of the case. Lone Pine-type case management orders may be more likely, and the pivotal and more productive issue for both sides may be shifting to specific causation. 

Listen as our stellar panel discusses the increased importance and scrutiny of specific causation evidence in toxic tort litigation, outlines strategies for testing and using methods of differential etiology, and offers practice takeaways for plaintiffs and defendants.