Expert Decisions
The Expert Decisions section tracks expert decisions in the toxic tort space to spot trends and identify how courts have handled the opinions of repeat experts.
2025 Decisions
October 2025
Georgia Court of Appeals Applies Eleventh Circuit Standard
October 31, 2025 | Sterigenics US LLC v. Mutz, No. A25A1377 (Ga. App. 2025).
The Georgia Court of Appeals held that because O.C.G.A. § 24-7-702 is “materially identical” to Federal Rule 702, Georgia courts should apply the Eleventh Circuit standard as enunciated in McClain v. Metabolife International Inc. and its progeny in determining the admissibility of expert testimony on general causation in toxic tort cases. Finding the trial court did not apply that standard in ruling on the defendant’s motions to exclude expert testimony on general causation and motion for summary judgment based on a lack of proof of general causation, the state court of appeals vacated the trial court’s order and remanded.
Georgia Court Grants Motions to Exclude Experts and Motion for Summary Judgment
October 17, 2025 | Mutz v. Sterigenics U.S. LLC, No. 20-A-3448 (Ga. St. Ct. 2025).
The State Court of Cobb County granted the defendants’ motions to exclude the plaintiffs’ specific causation experts and for summary judgment, finding the plaintiffs’ expert testimony was inadmissible and the plaintiffs lacked admissible proof on specific causation to survive summary judgement. The court excluded the plaintiffs’ expert because his opinions of the defendant’s ethylene oxide emissions and the plaintiff’s alleged exposures and cancer risks were not based on reliable data and his opinions on background ethylene oxide levels were unreliable; the court also excluded the plaintiffs’ other experts who relied on his opinions.
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September 2025
The Middle District of Florida Admits and Excludes Causation Experts in Products Liability Daubert Challenge
September 23, 2025 | Robinson v. 3M Co., No. 8:24-cv-00828 (M.D. Fla.).
The Middle District of Florida ruled on Daubert motions in a products liability case, admitting the plaintiff’s general and specific causation experts after finding their methodologies reliable and opinions supported by epidemiological and engineering evidence. The court specifically found that the experts’ methodologies—such as computational fluid dynamics modeling and differential diagnosis—were tested, peer-reviewed, and appropriately applied to the facts, satisfying Rule 702’s requirements for reliability and fit. The court excluded only those opinions that were speculative or lacked sufficient data, emphasizing that these deficiencies failed the reliability prong of Daubert, while disputes over the strength of the studies or conclusions went to weight, not admissibility. The court’s detailed analysis addressed the reliability of the experts’ methods, the sufficiency of their data, and the fit between the expert opinions and the facts of the case.
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August 2025
The Fourth Circuit Reverses Exclusion of Air Modeling Expert in Medical Monitoring Class Action
August 18, 2025 | Sommerville v. Union Carbide Corp., No. 24-1491 (4th Cir.).
The Fourth Circuit reversed the district court’s exclusion of the plaintiff’s expert and grant of summary judgment for lack of standing in a toxic tort medical monitoring case. The district court had excluded expert testimony on exposure modeling for being unreliable under Rule 702. The divided appellate court reversed, viewing the problems with the expert’s opinions as data inputs and credibility issues that the court held were not grounds for exclusion under Fourth Circuit law, and that the plaintiff’s alleged injury under West Virginia law was sufficient for Article III standing.
Challenges to Medical and Toxicology Experts in Jet Fuel Contamination Trial
August 7, 2025 | Feindt v. United States, No. 1:22-cv-00397 (D. Haw.).
The District of Hawaii addressed Daubert challenges to both sides’ medical and toxicology experts in a bench trial over jet fuel contamination, admitting expert testimony on general and specific causation when methodologies were reliable and opinions supported by evidence, but excluding opinions that were speculative or not based on sufficient facts. The court found the experts’ approaches reliable under Rule 702 because they used established toxicological and medical criteria, including temporality, dose-response, and differential diagnosis, and systematically ruled out alternative causes. The court excluded opinions only if the methodology was not reliably applied to the facts or if the expert’s opinion was based on speculation rather than sufficient data, as required by Daubert. The court provided a detailed assessment of each expert’s methodology, the factual basis for their opinions, and the application of Rule 702 to the complex scientific and medical issues in the case.
California Court Excludes Speculative and Unfounded Expert Testimony in Talc Litigation
August 1, 2025 | Moore v. Johnson & Johnson, No. 21STCV05513 (Cal. Super. Ct.).
A California state court excluded expert opinions in talc litigation that were speculative or lacked a reliable scientific basis, holding they did not meet the reliability and relevance requirements of California’s Rule 702 analog. The court excluded causation opinions not based on sufficient facts or reliable methodology, such as those relying on newspaper articles or non-testifying experts. In contrast, the court admitted expert testimony when the proponent established a reliable foundation, including an expert’s article and key, finding her methods for asbestos detection in talc sufficiently reliable. Disputes over interpretation of the expert’s findings were deemed issues of weight, not admissibility. Experts were permitted to rely on materials reasonably used in the field, but their opinions had to be grounded in reliable principles and methods properly applied to the facts.
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July 2025
Delaware Supreme Court Bars NDMA-Based Expert Testimony
July 10, 2025 | In re Zantac (Ranitidine) Litigation, No. 255, 2024 (Del.).
The Delaware Supreme Court reversed the superior court’s order admitting expert testimony linking NDMA exposure from ranitidine to cancer. The court held that Delaware law requires trial courts to evaluate the reliability of scientific opinions and that the plaintiffs’ experts failed to bridge the gap between ranitidine ingestion and harmful NDMA levels. The decision precluded thousands of Zantac claims from proceeding on the expert record as presented, clarifying that experts must reliably link the product at issue to the alleged harm, not just the toxic agent in the abstract.
Fifth Circuit Upholds Exclusion of Causation Experts in Oil Spill Toxic Tort Case
July 10, 2025 | Williams v. BP Exploration & Production Inc., No. 24-60095 (5th Cir.).
The Fifth Circuit affirmed exclusion of two causation experts in a Deepwater Horizon toxic tort case, finding their methodologies unreliable under Rule 702. The first expert’s differential etiology failed to evaluate alternative causes, and the second’s report contained errors and unreliable exposure assumptions. The court emphasized that the proponent must prove reliability, and without admissible expert testimony on specific causation, summary judgment for BP was proper.
District Court Denies Certain Motions to Exclude Groundwater Contamination Experts
July 10, 2025 | Suffolk County Water Authority v. Dow Chemical. Co., No. 2:17-cv-06980 (E.D.N.Y.).
The Eastern District of New York denied certain motions to exclude the plaintiff’s experts in a groundwater contamination case. The court rejected challenges to the experts’ statistical models and datasets that it said went to the weight rather than the admissibility of the evidence. The court excluded other opinions that lacked a sufficient factual basis or were legal conclusions.
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June 2025
Sixth Circuit Upholds Exclusion of Flood Causation Expert in Mining Case
June 23, 2025 | Baker v. Blackhawk Mining LLC, No. 23-5490 (6th Cir.).
The Sixth Circuit affirmed the exclusion of expert testimony that sought to link sediment-laden stormwater runoff from surface mining operations to catastrophic flooding. The court held that the expert’s modeling lacked site-specific calibration, failed to use accepted hydrologic modeling, and failed to address alternative flood causes, making the opinion inadmissible under Rule 702. The decision highlights the necessity for site-specific data and a reliable methodology in toxic tort and environmental cases.
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2024 Decisions
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January 2024
California Court Reinstates Expert Testimony in Diesel and Benzene Case
January 4, 2024 | Garner v. BNSF Railway Co., No. D082229 (Cal. App. Ct.).
The California court of appeal reversed the trial court’s exclusion of expert testimony, allowing the plaintiff’s experts to testify that long-term occupational exposure to diesel exhaust and benzene contributed to non-Hodgkin lymphoma. The court held that the experts’ reliance on a synthesis of available data, including peer-reviewed studies and scientific judgment, satisfied the admissibility standards under Sargon. The appellate court rejected the trial court’s requirement for epidemiological studies directly linking diesel exhaust to lymphoma, emphasizing that causation in toxic tort cases can be based on a weight-of-the-evidence approach and that the absence of direct studies does not render expert testimony inadmissible if the methodology is sound.
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