Tannen Maury/ Bloomberg News

More than 2,100 suits by users of the acne drug Accutane who developed Crohn’s disease have been reinstated after an appeals court ruled that expert testimony on behalf of plaintiffs was improperly excluded by the trial judge.

Atlantic County Superior Court Judge Nelson Johnson exceeded his role as a gatekeeper when he concluded that plaintiffs’ experts on gastroenterology and epidemiology were using accepted scientific methods to analyze the evidence in the case, the appeals court said. The decision also said the judge incorrectly determined the credibility of the testimony by plaintiffs’ experts. The appeals court reversed an order barring expert testimony by the plaintiffs’ experts and another order dismissing 2,174 cases.

Friday’s decision was the second in one week’s time from the Appellate Division that reversed dismissal of multicounty litigation cases concerning Accutane, which was marketed by Hoffmann-La Roche Ltd. On Tuesday, a different panel of the Appellate Division reinstated a different set of 335 cases on other grounds. The week’s rulings bring the aggregate number of Accutane cases pending in Atlantic County to more than 2,500.

The plaintiffs appealed rulings that Johnson barred testimony from Arthur Kornbluth, a gastroenterology expert for the plaintiffs, and biostatistician David Madigan, an epidemiological expert for the plaintiffs. Both Kornbluth and Madigan were critical of a series of eight epidemiological studies that showed that users of Accutane were not at increased risk of developing Crohn’s disease.

Kornbluth and Madigan said they favored other studies on the subject, including some in which dogs developed bowel problems after being administered Accutane. Johnson said Kornbluth’s “contrived reasoning is not supported by the scientific community as a reliable basis for making causal determinations,” and said his testimony was “replete with what can be described as convenient assumptions.” Johnson said Madigan’s opinions were conclusion-driven, rather than methodology-based. On appeal, the plaintiffs argued Johnson substituted his own view of the studies for that of the plaintiff experts, calling him “an expert on a mission.”

The Appellate Division panel of Judges Susan Reisner, Ellen Koblitz and Thomas Sumners Jr. said Johnson wrongly concluded that the plaintiffs’ experts ignored the epidemiological studies in favor of less reliable evidence. “The experts did not ignore the studies. Rather, in extensive and detailed testimony, they opined that most of the studies were unreliable, and they explained in considerable detail the reasons for those opinions,” Reisner wrote for the court. The judge’s duty was “to weed out ‘junk science,’ not to shield jurors from hearing expert testimony that is scientifically-based but unpersuasive to the trial judge,” Reisner wrote.

Hoffmann-La Roche was represented by Paul Schmidt of Covington & Burling in Washington. A spokeswoman for the company, Amanda Fallon, said in a statement about the ruling, “The medical and scientific communities have demonstrated that there is no link between Accutane and Crohn’s disease. Roche is disappointed that the appellate court is allowing the plaintiffs’ experts to offer opinions that disregard this science, opinions which they themselves have only offered in lawsuits. Roche will ask the New Jersey Supreme Court to take up this crucial issue, which has the potential to impact a broad range of lawsuits involving important public health issues.”

David Buchanan of Seeger Weiss in New York, who argued for the plaintiffs, did not return a call about the case. Other plaintiff lawyers on the case referred questions to Buchanan.