Is Kelly a basis independent of Sargon to challenge a novel scientific theory?

Can an expert opinion, expressing a novel scientific theory but not utilizing a novel scientific methodological technique or process, pass muster under Sargon Enterprises, Inc. v. University of Southern California (2012) 55 Cal.4th 747 (Sargon) yet be inadmissible under People v. Kelly (1976) 17 Cal.3d 24 (Kelly)? That issue is discussed at length in the recent First District Court of Appeals decision, Bader v. Johnson & Johnson et al., (2022) 2022 DJDAR 12986 (Bader). Both in a fulsome main opinion footnote and in a thoughtful concurring opinion by Justice Streeter, Bader suggests that Sargon and Kelly are independent bases for challenges to expert opinions involving novel theories, not just novel methodological techniques or processes. This discussion in Bader is dicta because no Kelly challenge - only a challenge premised on Sargon - was actually asserted to the subject expert opinion. The Bader court takes pains not to speculate as to the outcome had a Kelly challenge been made. Nonetheless, Bader's Kelly discussion is an important contribution to the jurisprudence of expert opinion admissibility.

Bader is an asbestos mesothelioma case involving Johnson & Johnson talc baby powder and other defendants' cosmetic talc products. The competing evidence at trial explored in detail the esoteric scientific controversies concerning the definitions and properties of the mineral substances scientists and regulators call asbestos, asbestiform talc and fibrous talc. These included the geological and regulatory definitions of "asbestos," and the size (cleavage fragments) and shapes ("aspect ratios") of the relevant minerals. The Sargon/Kelly discussion arose relative to a novel scientific theory contained in the opinion of plaintiff's medical causation expert David Egilman, M.D. At the end of his trial testimony, the jury posed this question to Dr. Egilman: "Is it your opinion that cleavage fragments of certain size, shape and structure, even if nonasbestos, are carcinogenic and cause mesothelioma?" Dr. Egliman responded, "No. It has to be chemically asbestos. Or similar. Fibrous talc is essentially similar. So just a cleavage fragment of some random rock, okay, that not - would not, in my opinion - there's not data to show that that would cause mesothelioma." Bader, supra at 2022 DJLADJ 12990.

Pretrial, defendants had filed a motion in limine to exclude Dr. Egilman's anticipated testimony "on the ground that he had no scientific foundation to opine that fibrous, or asbestiform, talc causes mesothelioma." Id. at 2022 DJLADJ 12989. The trial court, confronted with competing scientific materials including varying conclusions from an authoritative body, the International Agency for Research on Cancer, exercised its discretion to admit Dr. Egilman's opinion. Defendants contended on appeal that the trial court erred: "Dr. Egilman's opinion lacks a reliable foundation and should have been excluded as speculative under Sargon because there is no scientific support for his opinion that fibrous talc causes mesothelioma." Id. Both defendants and the Bader court appear to agree that in reaching his opinion, Dr. Egilman did not employ a novel scientific methodology or technique; instead, he expressed a novel scientific theory. Ultimately, the Court of Appeal affirmed in a unanimous opinion authored by Justice Brown, finding no abuse of discretion in the trial court's admitting the opinion.

The matter could have been left to rest there. But the Bader court went further, noting in footnote 11 of the main opinion, "To the extent that defendants now contend that the trial court should have excluded Dr. Egilman's fibrous talc opinion because it was a novel theory not generally accepted within the relevant scientific community, we emphasize that their motion to exclude did not challenge his testimony based on Kelly and its progeny. We express no view on whether such an argument would have been successful."

The footnote goes on to identify a possible conflict in the law concerning whether Kelly challenges apply to novel theories as well as novel scientific techniques or processes. It directs readers to compare People v. Davis (2022) 75 Cal.App.5th 694, 711 ("The Kelly test applies only to expert testimony ' " ' "based, in whole or in part, on a technique, process, or theory which is new to science and, even more so, to the law" ' ") with Roberti v. Andy's Termite (2002) 113 Cal.App.4th 893, 901-902, which reversed the trial court's exclusion of expert opinion testimony that pesticide caused plaintiff's autism, noting, "[Plaintiff's experts] did not rely upon any new scientific technique, device or procedure that has not gained general acceptance in the relevant scientific or medical community. Rather it was the theory of causation, that [the pesticide] caused plaintiff's autism, that has not gained general acceptance in the relevant medical community. The Kelly test is not applicable even though the proffered evidence presents a new theory of medical causation."

Justice Streeter substantially expanded on the point in the concurring opinion, agreeing that "the logic" of Dr. Egilman's novel theory permitted its admission under Sargon, but that the potential problem was its "newness," a Kelly issue. Bader, supra, 2022 DJDAR at 13003. Justice Streeter analyzed modern Kelly cases, observing, "And notably, the post-Sargon Kelly cases utilizing the broader formulation (i.e., [People v.] Peterson [(2020) 10 Cal.5th 409)] and [People v.] Jackson [(2016) 1 Cal.5th 269)]) emphasize that the Kelly test is not limited to methodological "techniques" or "processes," which suggests that there may be some types of causation opinions - i.e., scientific opinions based on untested hypotheses - that are subject to Kelly." Justice Streeter further commented on the importance of consideration of error rates "so that conclusions based on a mere coincidence and association may be distinguished from reliable conclusions suggesting actual causality." Bader, supra, 2022 DJDAR at 13004. He wrote, "I have no idea how Dr. Egilman's fibrous talc opinion would stand up to scrutiny against such an assessment, but I suspect it may have fallen short, particularly given its apparent 'newness' in the field of asbestos causation." Id. Justice Streeter concludes his concurring opinion with this sentence: "The proper vehicle for mounting such a challenge, however, was a Kelly objection and a request for an Evidence Code section 402 hearing to assess the scientific foundation for the opinion, not a Sargon objection with back-and-forth arguments from lawyers on an undeveloped record about the 'logic' of the opinion." Id.

We will all be watching closely as these issues are further developed in future cases.