Insights & Events

Litigation Daily published an expert opinion article authored by Hollingsworth LLP attorneys Aleksandra Rybicki, Stephanie Salek, and Sally Levin regarding a recent ruling from the United States Court of Appeals for the Fourth Circuit that represents a step backward in the effort to apply amended Federal Rule of Evidence 702 properly.

In December 2023, Rule 702 was amended to clarify that a proponent of expert testimony must demonstrate that it is “more likely than not” that, among other things, “the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.” In explaining the need for the amendments, the Advisory Committee bemoaned that “many courts have held that the critical questions of the sufficiency of an expert’s basis, and the application of the expert’s methodology, are questions of weight and not admissibility,” but “[t]hese rulings are an incorrect application of Rules 702 and 104(a).” Yet the court’s majority in Sommerville v. Union Carbide repeatedly relied on this superseded “weight-not-admissibility” approach to analyzing expert testimony, in contradiction to the Advisory Committee’s clear guidance.

In Sommerville, plaintiffs sought medical monitoring for an alleged increased risk of developing cancer allegedly resulting from their “chronic” exposure to ethylene oxide, or EtO — a chemical used to sterilize over 50% of all medical equipment — released from Union Carbide’s Charleston, West Virginia, facility. They offered Dr. Ranajit Sahu to model EtO emissions to establish the plaintiffs’ exposure. The district court correctly excluded Dr. Sahu’s testimony under Rule 702, finding his opinions were “not based upon sufficient facts or data because the inputs he uses in the air model are speculative and are premised on assumptions that do not accurately represent the defendants’ operations in South Charleston.” The Fourth Circuit reversed in an opinion that contradicts the letter and purpose of the recent amendments to Rule 702, falling back on the outdated refrain that “questions regarding the factual underpinnings of the [expert’s] opinions affect the weight and credibility of the witness’ assessment, not its admissibility.”

Opinions like Sommerville that rely on the outdated “weight-not-admissibility” refrain grant experts a “get-out-of-Daubert-free” card and highlight the need for practitioners to emphasize the purpose of Rule 702’s amendments at every opportunity. It is incumbent upon practitioners to focus courts’ attention on proper applications of Rule 702 to keep junk science from reaching a jury.

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