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New Jersey Adopts Daubert Factors for the Admissibility of Expert Testimony

William Marsillo

New Jersey Adopts Daubert Factors for the Admissibility of Expert Testimony
aerogondo via Getty Images

Until the New Jersey Supreme Court’s decision in In re Accutane Litigation, 191 A.3d 560 (N.J. 2018), the standard governing the admissibility of expert scientific testimony under New Jersey law was as well established as it was unclear. In Accutane, the New Jersey Supreme Court adopted the use of Daubert factors for assessing the admissibility of expert testimony in civil cases. In the underlying multi-county litigation, the plaintiffs filed thousands of cases claiming that that use of the prescription acne drug Accutane (isotretinoin) caused inflammatory bowel disease in the form of ulcerative colitis and Crohn’s disease. The state supreme court’s decision concerned the admissibility of the plaintiffs’ experts, Dr. Arthur Asher Kornbluth, a gastroenterologist, and Dr. David Madigan, a statistician. Dr. Kornbluth opined that there was a causal relationship between Accutane and Crohn’s disease and that epidemiological studies showing no causal connection, relied on by the defendants, were flawed. Dr. Madigan did not offer an opinion on causation, focusing solely on showing that the defendants’ epidemiological studies were flawed.

Proceedings Before the Trial Court

After an eight-day hearing on the admissibility of expert evidence referred to as a Kemp hearing (see Kemp v. New Jersey, 174 N.J. 412 (2002)), the Accutane trial court excluded Dr. Kornbluth’s and Dr. Madigan’s testimony, finding that “[w]hile both Plaintiffs’ experts are eminently qualified, their reasoning and methodology slanted away from objective science and in the direction of advocacy” and were “motivated by preconceived conclusions.” In re Accutane Litig., No. 271(MCL), 2015 N.J. Super. Unpub. LEXIS 3045, at *17 (N.J. Super. Ct. L. Feb. 20, 2015). According to the trial court, the fundamental issue was that the experts were selective in relying on evidence such as case reports and animal studies that supported their opinions, while disregarding more compelling and more probative epidemiological studies that found no causal connection.

The Appellate Division Says “No”

On appeal, the Appellate Division reversed, finding that the trial court “went beyond its gatekeeping function . . . and improperly determined the weight and credibility of the experts’ testimony.” In re Accutane Litig., 165 A.3d 832, 837 (N.J. Super. Ct. App. Div. 2017). In addressing the standard of review, the Appellate Division held that although it typically reviewed “the admission or exclusion of expert testimony for an abuse of discretion,” appellate courts “need not be as deferential to the trial court’s ruling on the admissibility of expert scientific evidence[.]” Id. at 857–58. According to the Appellate Division, the trial court erred because the plaintiffs’ experts were “indisputably extremely well-qualified” and had “considered all of the relevant data and information, applied appropriate methodology in analyzing the epidemiological studies, and expressed valid reasons for rejecting the conclusions of some of the epidemiological studies and in accepting other studies as supportive of their opinion.” Id. at 863. The Appellate Division further expressed its view that the plaintiffs’ experts had “explained the scientific bases for their criticism of the [epidemiological] studies,” not that they had ignored or disregarded those studies, as the trial court found. Id.

The Supreme Court Weighs In

The New Jersey Supreme Court reversed the decision of the Appellate Division. The court held that (i) trial court decisions on the admissibility of expert testimony in civil matters are to be reviewed under an abuse of discretion standard, (ii) the trial court did not abuse its discretion in excluding the plaintiffs’ experts, and (iii) Daubert factors should be incorporated for use by New Jersey trial courts when assessing the admissibility of expert testimony in civil cases.

With respect to the standard of review, the court noted that the Appellate Division erred in relying on criminal case law, where the less deferential approach applied because New Jersey still applies the Frye standard in criminal matters. In re Accutane, 191 A.3d at 590. But that approach is “not appropriate in the context of a civil mass tort case, where the trial court has been entrusted with methodology-based review as the gatekeeper of expert testimony.” Id. Accordingly, the court “reaffirm[ed] that the abuse of discretion standard applies in the appellate review of a trial court’s determination to admit or deny scientific expert testimony on the basis of unreliability in civil matters.”

The supreme court further held that the trial court had not abused its discretion in performing its gatekeeper function. In describing a trial court’s gatekeeper function with respect to the admissibility of expert testimony in “a new and evolving area of medical causation,” the supreme court stated that a trial court’s primary function “is to distinguish scientifically sound reasoning from that of the self-validating expert, who uses scientific terminology to present unsubstantiated personal beliefs.” Id. at 589. The court noted that the trial court properly considered the hierarchy of scientific evidence set forth in the Federal Judicial Center’s Reference Manual on Scientific Evidence, which places case reports at the bottom of the hierarchy and statistically significant epidemiological studies at the top. Contrary to the Reference Manual hierarchy, which had been “accepted generally in the scientific community” (id. at 592), the plaintiffs’ experts “employed a methodology whereby they disregarded eight of nine epidemiological studies and relied on case reports and animal studies to support their opinion.” Id. at 591. While “initial animal studies may have suggested a possible causal connection between Accutane and Crohn’s disease, [] since that time a uniform body of epidemiological evidence ha[d] dispelled any such theory.” Id. The plaintiffs’ causation expert, however, had rejected the epidemiological studies—all of which found no causal association—and put forth “his own alternative opinion that a causal association was present based on lesser forms of evidence” and “never submitted his ideas concerning biological mechanism or Accutane’s relation to Crohn’s disease for peer review or publication.” Id. at 592. Summing up, the court found it “unsurprising” that the trial court had excluded the plaintiffs’ experts and held that the trial court had not abused its discretion because it “explained its reasons for concluding that plaintiffs’ experts deviated from core scientific principles and strayed from their own claimed methodology in order to reach their conclusions.” Id. at 593.

The supreme court then went on to address whether its case law on the gatekeeping function performed by trial courts in reviewing expert testimony needed clarification. Assessing whether to adopt Daubert or incorporate the use of its factors, the court was clear that New Jersey case law already was aligned with the principles set forth in the “Daubert trilogy,” which included General Electric Co. v. Joiner, 522 U.S. 136 (1997), and Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999). That is, both New Jersey case law and the Daubert trilogy cases “ask whether an expert’s reasoning or methodology underlying the testimony is scientifically valid.” In re Accutane, 191 A.3d at 594; see also In re Accutane Litig., No. 271 (MCL), 2020 N.J. Super. Unpub. LEXIS 123 at *2 (N.J. Super. Ct. App. Div. Jan. 20, 2020) (affirming exclusion of plaintiffs’ causation experts on issue of whether there was causal link between use of Accutane and ulcerative colitis and noting that the supreme court’s decision applies retroactively in part because the supreme court “perceive[d] little distinction between Daubert’s principles regarding expert testimony and our own”) (internal quotations omitted)). The supreme court simply made express that the non-exhaustive list of factors identified in Daubert “should be incorporated for use by” New Jersey courts because those factors provide a “helpful—but not necessary or definitive—guide for our courts to consider when performing their gatekeeper role concerning the admission of expert testimony.” In re Accutane, 191 A.3d at 594 (setting forth Daubert factors). The court was quick to add, however, that because “there is no monolithic body of case law uniformly or even consistently applying Daubert,” it did not intend by its decision to “sweep in adherence to the various approaches taken among the circuits and state jurisdictions when applying the Daubert factors.” Id. at 595.


Accutane involved highly qualified experts and a long history in which the sort of evidence that the trial court ultimately rejected had been previously relied on and considered with approval. The decisions are a helpful reminder that practitioners should remain mindful of the evidence underlying expert opinions at all stages of a litigation—especially product liability actions that may persist for years—and reassess whether issuance of additional studies support or undermine an expert’s opinion and, if so, what must be done to maximize admissibility arguments.