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In product liability litigation, the straightest path to a favorable outcome for the defense is disqualification of the plaintiff’s expert. In a unanimous decision, New Jersey’s Supreme Court in Beavan v. Allergan U.S.A., Inc., A-53-24 (N.J. May 27, 2026), has substantially bolstered the defense position in that critical fight. The decision underscores and amplifies the rigorous gatekeeping framework established in In re Accutane Litigation, 234 N.J. 340 (2018), clarifying that its requirements apply universally to all civil cases, including those in which plaintiffs rely on a differential diagnosis methodology. For product liability defendants, the decision provides concrete, immediately actionable tools for challenging plaintiff expert testimony at the pretrial stage.
The Factual Background
Beavan arose from a pharmaceutical product liability action in which the plaintiff alleged that she sustained serious eye injuries, ultimately resulting in total vision loss in one eye, following an injection of Ozurdex, a steroid pellet manufactured by Allergan for the treatment of ophthalmic conditions. Allergan had issued a recall covering certain Ozurdex lots after discovering that a silicone particulate could potentially detach during injection. The lot used in the plaintiff's treatment was among those recalled. The plaintiff asserted claims under the New Jersey Product Liability Act (PLA) for manufacturing defect and failure to warn.
To prove causation, the plaintiff designated two expert witnesses: Dr. Lalezary, a retained expert who submitted a written report relying on a differential diagnosis methodology, and Dr. Phillips, the plaintiff’s treating physician who was designated to testify on causation but for whom no written report was served. Differential diagnosis, as the Court noted in Creanga v. Jardal, is a medical process by which a physician systematically compares and contrasts plausible causes of a condition, first "ruling in" all potential causes and then "ruling out" those that did not produce the condition through a process of elimination. In the legal setting, the methodology is used to establish that a particular product, substance, or event—rather than other potential causes—was the cause of the injury. Both experts conceded that no silicone particulate was ever observed in the plaintiff's eye. Their causation theory rested on the temporal relationship between the injection from a recalled lot and the plaintiff's symptoms, coupled with the absence of complications from prior Ozurdex injections.
The trial court rejected the defendants’ challenge to the admissibility of those experts’ opinions and, by extension, denied summary judgment without conducting an Accutane analysis. The Appellate Division reversed, finding amongst other things that the experts’ opinions were unreliable and inadmissible per Accutane, and, once the experts were excluded, that summary judgment was appropriate.
What the Court Held
Accutane Applies to All Civil Expert Disputes — Including Differential Diagnosis
The Court has now declared unequivocally that the Accutane gatekeeping framework "applies to all civil cases in which the parties dispute the reliability of expert testimony under N.J.R.E. 702 and 703." The Court specifically rejected the plaintiff's argument that the use of differential diagnosis to prove causation, as validated by Creanga v. Jardal, 185 N.J. 345 (2005), independently established the admissibility of those experts' opinions without need for an admissibility review consistent with Accutane. This line of argument sought a backdoor around the exacting review of a trial court applying the Daubert-style analysis that Accutane articulated. That door is now closed.
Procedurally, the Court reversed the Appellate Division’s determination that summary judgment was appropriate or that the experts’ opinions should be excluded on the basis that the record, lacking an analysis of the Accutane factors, was incomplete. While not making pretrial evidentiary hearings mandatory in all cases, the Court "strongly encourage[d]"the trial court to conduct such a hearing given the complexity of the causation issue. As such, it remanded with specific direction not only to conduct such an analysis but provided the specific blueprint for how such an analysis should be conducted in a differential diagnosis setting.
The Court emphasized that Accutane’s gatekeeping inquiry must be conducted with respect to both steps of the differential diagnosis process as defined in Creanga:
In the first step — the "rule in" — the trial court must assess the methodology by which the expert determines that a particular cause is a plausible cause of the plaintiff's harm. The Court emphasized that expert testimony that "rules in a potential cause that is not . . . capable" of causing the patient's condition "is unreliable" and that testimony that "neglects to consider a hypothesis that might explain the clinical findings under consideration may also be unreliable."
In the second step — the "rule out" — the trial court must scrutinize the methodology the expert used to eliminate alternative causes. The expert "must provide reasons for rejecting alternative hypotheses 'using scientific methods and procedures'" and "the elimination of those hypotheses must be founded on more than 'subjective beliefs or unsupported speculation.'"
This two-step framework creates discrete opportunities to challenge an expert's causation opinion at each stage of the analysis. Where a plaintiff's expert has failed to "rule in" the defendant's product through reliable general causation evidence or has failed to adequately "rule out" well-documented alternative causes, the defense now has clear doctrinal authority for seeking exclusion.
Practical Implications for Product Liability Defendants
Beavan provides product liability defense counsel with several concrete strategic advantages:
First, the decision makes clear that no causation methodology, however well-established in clinical medicine, is exempt from Accutane scrutiny. This expands the scope of matters in which defense counsel should reasonably consider filing admissibility challenge motions to cover differential diagnostics. These motions should explicitly track the structure provided by Beavan to initially challenge the “rule in” analysis by attacking the reliability of cited evidence that the defendant’s product is capable of causing the harm alleged and thereafter, separately, attacking the failure to adequately rule out identified documented alternative causes through scientific methods.
Second, defense counsel should routinely seek pretrial evidentiary hearings in conjunction with expert admissibility challenges. The Supreme Court's strong encouragement of such hearings gives trial courts every reason to grant these requests and creates appellate issues if they do not.
Finally, defense counsel should coordinate expert exclusion motions with summary judgment motions, because if the expert is excluded, summary judgment on causation follows.
Looking Ahead
Beavan v. Allergan is a significant win for the defense bar in New Jersey. By clarifying the admissibility of differential diagnosis opinions and confirming the universal reach of Accutane, the New Jersey Supreme Court has placed the state firmly among those jurisdictions requiring rigorous pretrial scrutiny of expert causation testimony in product liability cases. The decision offers a roadmap for challenging plaintiff expert testimony that, when followed, creates meaningful opportunities for outcomes favorable to the defense in product liability claims.
