New Rule 702 Helps Judges Keep Bad Science Out Of Court

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Judges’ commitment to rigorous policing of science is paramount in safeguarding the integrity of the legal system.

This op-ed was originally published by Law360.

In civil litigation across the U.S., the specter of scientific evidence that is, at best, questionable, looms large. Some judges diligently exercise their gatekeeping function to weed out so-called junk science, fortified by recent amendments to Federal Rule of Evidence 702.

But in other courtooms, there is the risk that dubious theories may be introduced, and expert witnesses whose testimony has been rejected elsewhere may be allowed to testify.

One of the first decisions under the newly amended Rule 702, which went into effect Dec. 1, 2023, spotlighted the critical role judges play in preventing the entry of questionable science into courtrooms.

In re: Acetaminophen — ASD-ADHD Products Liability Litigation is a multidistrict litigation proceeding probing the alleged affects on children of acetaminophen use during pregnancy. In December, Judge Denise Cote of the U.S. District Court for the Southern District of New York demonstrated the gatekeeping her position requires by barring evidence from the plaintiffs’ experts.[1]

The MDL complaint asserted that maternal use of acetaminophen leads to attention deficit hyperactive disorder and autism spectrum disorder in children. Judge Cote underscored the “great public health significance” of the trial, emphasizing the profound consequences for families and communities.[2]

By excluding testimony from the plaintiffs’ experts, she highlighted the responsibility of judges as gatekeepers, particularly under the reinforced guidelines of Rule 702.

Judge Cote’s approach extended beyond evaluating experts’ qualifications, focusing keenly on methodologies — an additional emphasis under the amended guidelines. She revealed a commitment to impartiality and thorough scrutiny, noting how plaintiffs experts selectively cited articles to bolster their position.[3]

This principled approach was echoed in In re: Zantac (Ranitidine) Products Liability Litigation, in the U.S. District Court for the Southern District of Florida, dismissed by Judge Robin Rosenberg last year.[4] Her decision also rested on exposing experts’ flawed methodologies.

The plaintiffs’ attempt to prove that the active ingredient in Zantac, ranitidine, could become carcinogenic, relied on findings from a private lab, Valisure LLC. Judge Rosenberg noted that Valisure’s testing conditions were highly improbable, including heating the product to well over 200 degrees, and raised questions about the credibility of the lab’s findings.

Such critical thinking and methodical review should be the standard across jurisdictions. Judges should emulate the approaches of Judge Cote and Judge Rosenberg when assessing scientific evidence submitted for trial.

Regrettably, not all judges consistently apply such rigorous standards. A stark contrast can be drawn when examining cases involving talcum powder and glyphosate, the active ingredient in Roundup weedkiller.

In litigation concerning Roundup, substantial awards in plaintiff-friendly forums primarily rest on a single report from the International Agency for Research on Cancer. This 2015 report — in stark contrast to more than 800 scientific studies as well as analyses by the U.S. Environmental Protection Agency and Health Canada — concluded that glyphosate is “probably carcinogenic.”[5]

A closer look at IARC’s process revealed serious flaws. An “invited specialist,” Christopher Portier, who had no prior experience working with glyphosate, advised the study while being paid by an anti-pesticide group and law firms suing over glyphosate.[6] Following Portier’s arrival at IARC, the final glyphosate study was altered in at least 10 ways to either remove or reverse conclusions finding no evidence of carcinogenicity.[7]

Regardless, judges continue to permit dubious science as evidence. To see the impact on litigation results, look no further than the $2.25 billion verdict in McKivison v. Monsanto, involving a single plaintiff, in the Philadelphia Court of Common Pleas last month.[8]

The Pennsylvania Supreme Court helped pave the way for this eye-popping verdict by adopting a lesser standard for expert evidence, making it easier for questionable science to permeate state courthouses.

In its 2020 decision in Walsh v. BASF Corp., the court refused to recognize the role of a trial court judge as a gatekeeper over the reliability of expert testimony.[9] Pennsylvania is one of the last remaining states to use the weaker Frye standard when evaluating expert evidence.

Similarly, questionable scientific evidence has served as the basis for multimillion-dollar awards related to the effects of talcum powder use. The American Cancer Society acknowledges the mixed link between ovarian cancer and talc powder use, emphasizing the minimal increase in risk, if any.[10]

Barden v. Brenntag North America Inc., a 2019 New Jersey talc trial that culminated in a $224 million jury verdict against Johnson & Johnson, featured testimony from three of the mass tort bar’s favorite expert witnesses on talc: Dr. James Webber, Dr. Jacqueline Moline and Dr. William Longo.[11] Moline is now the subject of a lawsuit alleging she persistently and knowingly disseminated false and disparaging statements tying Johnson & Johnson’s products to cancer.[12]

Barden was overseen by Judge Ana Viscomi of the Middlesex County Superior Court, who failed to conduct hearings to assess the admissibility of the three expert witnesses’ testimonies, and denied Johnson & Johnson’s requests to do so. However, in October 2023, the New Jersey Court of Appeals tossed the verdict, and with it, the testimonies of all three experts.[13]

It found that the trial court abused its discretion by failing to exercise its gatekeeping function to bar unreliable expert testimony. This decision marks the second time that the New Jersey appellate court reversed a multimillion-dollar talc verdict on grounds of unreliable expert testimony. In April 2021, in Lanzo v. Cyprus Amax Minerals Co., the panel similarly excluded the testimonies of Webber and Moline, which had initially been allowed in by Judge Viscomi.[14]

Judges’ commitment to rigorous policing of science is paramount in safeguarding the integrity of the legal system. They must consistently apply the rules set forth in the new Rule 702 when evaluating scientific evidence to prevent the entry of dubious or unreliable information into the courtroom.

In doing so, they not only protect the rights of litigants but also uphold the principles of justice and fairness that underpin our legal system.

[1] In re: Acetaminophen — ASD-ADHD Prod. Liab. Litig. , No. 22MC3043 (DLC), 2023 WL 8711617 (S.D.N.Y. Dec. 28, 2023).

[2] Id. at 49.

[3] Id.

[4] In re: Zantac (Ranitidine) Prod. Liab. Litig. , 644 F. Supp. 3d 1075 (S.D. Fla. 2022), appeal dismissed, No. 23-10090-J, 2023 WL 2849068 (11th Cir. March 22, 2023), and appeal dismissed, No. 23-11047, 2023 WL 7426136 (11th Cir. Nov. 9, 2023).

[5] Government of Canada, Re-evaluation Decision RVD2017-01, Glyphosate (2017),

[6] RiskMonger, Greed, lies and glyphosate: The portier papers (2023),

[7] Kate Kelland, Glyphosate: Who cancer agency edited out ‘non-carcinogenic’ findings, Reuters Investigates (2017),

[8] McKivison v. Monsanto et al., No. 220100337 (Pa. Commw. Ct. 2024).

[9] Walsh v. BASF Corp. , 234 A.3d 446 (Pa., 2020).

[10] Talcum Powder and cancer: American Cancer Society,

[11] Barden v. Brenntag N. Am. Inc. , No. A-0047-20, 2023 WL 6430088 (N.J. Super. Ct. App. Div. Oct. 3, 2023).

[12] LTL MANAGEMENT LLC, Plaintiff, v. Dr. Jacqueline Miriam MOLINE, Defendant., 2023 WL 4547878.

[13] Barden v. Brenntag N. Am. Inc. , No. A-0047-20, 2023 WL 6430088 (N.J. Super. Ct. App. Div. Oct. 3, 2023).

[14] Lanzo v. Cyprus Amax Mins. Co. , 467 N.J. Super. 476, 254 A.3d 691 (App. Div. 2021).

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