Legal Intelligencer, “Same Product, Same Experts, Three Courts-Divergent Outcomes Spotlight Experts’ Role in Products Liability Law,” 11-25-2025

Kaufman Dolowich’s Erik Sardiña, New Jersey Partner, and Eileen Ficaro, Philadelphia Partner, co-authored an insightful article for The Legal Intelligencer examining three federal courts’ conflicting rulings in a products-liability case involving a striker-fired pistol that allegedly discharged without the user’s intent in three separate lawsuits.

Below is the full article:

In the past year, three federal appellate courts—the U.S. Courts of Appeal for the Tenth, Sixth and Third Circuits—issued major decisions involving the Sig Sauer P320, a striker-fired pistol alleged in three separate lawsuits to discharge without any intention by the user to do so. Although the cases arose in different jurisdictions, they presented nearly identical core issues: Was the P320 defectively designed? Can plaintiffs’ experts reliably testify that the absence of a manual safety caused their injuries? Were the plaintiffs’ experts’ conclusions that a design defect caused the injuries admissible? And when experts are
excluded, can a products liability claim survive?

Taken together, the decisions paint a complex picture. While all three courts agreed that the plaintiffs’ causation experts fell short under the federal rules of evidence on causation and permitted the same experts to testify as to the alleged design defects, they diverged sharply on what that meant for the viability of the claims. Two courts allowed the lawsuits to move forward despite the exclusion of causation testimony. One court ended the case entirely. Much of the difference turned on how each court understood the role of the jury, the complexity of firearm mechanics and the limits of expert methodology.

The Tenth Circuit: No Causation Expert, No Case

The Tenth Circuit’s June 2025 decision in Herman v. Sig Sauer (No. 23-6136) was the most defense friendly of the three. In Herman, the plaintiff, John Herman, was injured when his P320 discharged while he attempted to remove it—still in its holster—from his pants. There was not clear evidence about whether his finger or holster came in contact with the trigger at the time of the discharge. To prove his product-defect claims, he relied on two experts: a firearms design specialist and a human-factors expert. Both concluded that the pistol’s lack of a manual safety made it “unreasonably dangerous.”

But neither expert, the court emphasized, conducted any analysis of how the trigger might have been actuated during the incident. They could not identify whether Herman’s finger, clothing, a foreign object, or something else contacted the trigger. Without knowing what caused the trigger to move, they could not reliably opine that an alternative safety mechanism would have prevented the accident.

For the Tenth Circuit, this gap was fatal. Because the experts’ causation opinions were speculative, they were properly excluded. Since Oklahoma law required expert testimony on causation for a firearm design case of this complexity, Herman could not establish an essential element of his claims. Summary judgment for Sig Sauer was affirmed. In short for the Tenth Circuit under Oklahoma law: unreliable experts meant no causation evidence, and no causation evidence meant no trial.

The Sixth Circuit: Experts Limited—But the Jury Can Still Decide Causation

The Sixth Circuit took a starkly different approach in Davis v. Sig Sauer, (No. 24-5210), in January 2025. Like Herman, Timothy Davis alleged that his P320 fired while holstered, striking him in the leg. Like Herman, he presented the same two experts, who again opined that the lack of an external safety made the pistol unreasonably dangerous.

And again, the experts acknowledged they had not analyzed the precise mechanism of trigger actuation. They offered opinions about general risk patterns and alternative designs but not about whether those features would have prevented this shooting. The Sixth Circuit agreed that these causation opinions were inadmissible.

But the court did not agree that the exclusion of causation experts required dismissal. Instead, the court held that the experts’ testimony remained admissible for other essential elements—namely whether the pistol was defectively designed and whether safer alternative designs existed. The court then went further: although causation experts were excluded, a jury could still decide causation without expert testimony at all.

After hearing about the P320’s mechanics, alternative designs, and Davis’ own account of how the shooting occurred, the court reasoned, jurors could evaluate whether the absence of a manual or tabbed trigger safety was a substantial factor in causing the injury. Kentucky law did not demand expert testimony where jurors could infer causation from circumstantial evidence and common experience.

Thus, unlike the Tenth Circuit, the Sixth Circuit held that the absence of expert causation testimony did not doom the claim. With factual disputes remaining, summary judgment was reversed, and the case was remanded for trial.

The Third Circuit: Exclude the Experts, Trust the Jury

The Third Circuit’s August 2025 decision, Slatowski v. Sig Sauer (No. 24-1639), closely mirrored the Sixth Circuit’s approach. The case arose from a training drill in which a federal immigration agent’s holstered P320 fired into his hip as he drew it. The expert lineup was the same; the legal arguments were the same; the alleged defect was the same.

As in the other cases, the plaintiffs’ experts focused on the general risks posed by the P320 design but did not—and could not—explain what specifically caused the trigger to actuate in the incident at issue. The Third Circuit agreed with the district court that these causation opinions lacked the rigorous methodology Daubert requires.

But, echoing the Sixth Circuit, it concluded that the jury did not need expert assistance to determine causation. The jury would first hear admissible expert testimony explaining how the P320’s internal mechanisms work. It would then evaluate lay testimony, photographs, the holster involved, and the agent’s own account. From this record, the court explained, jurors could decide whether debris, fabric, or motion inside the holster might have depressed the trigger, and whether a tabbed trigger safety would have prevented that outcome.

Causation, the court stressed, was not “the sort of inscrutable mystery” that only an expert could decode. Instead, it was a classic jury question involving credibility, plausibility and conflicting interpretations of observable facts.

The court therefore affirmed the exclusion of expert causation testimony but reversed the grant of summary judgment.

The Expert-Testimony Divide

What explains the split of these courts, with one dismissing its case while the others advanced? All three circuits agreed on one key point: plaintiffs’ experts overreached by giving causation opinions unmoored to concrete facts.

Their methodology did not bridge the gap between general firearm-design criticism and the specific mechanics of each shooting. In none of the cases did the experts attempt to recreate the conditions leading up to the weapon discharges.

But from that shared foundation, the courts parted ways.

The Tenth Circuit treated causation as a technical question requiring expert assistance. Without reliable expert testimony, the plaintiff could not meet his burden. The Tenth Circuit declined to decide as a matter of law whether expert testimony is required in a product liability case, extended its reasoning that the causation element of litigant’s case “must be based upon probabilities, not possibilities,” and determined that Herman just did not identify any circumstantial evidence that establishes a probability of causation due to a design defect. The case therefore ended.

The Sixth and Third circuits, by contrast, took a more functional, jury-centric view. Once experts educated jurors about how the P320 functions, jurors could apply that knowledge to the facts of each incident. Because the ultimate question turned on factual inference—what most likely happened inside the holster—expert testimony was helpful but not indispensable to the causation question.

This interpretive divide has significant consequences. Under the Tenth Circuit’s approach, plaintiffs face a steep hurdle unless they can provide highly precise expert causation analysis. Under the Sixth and Third circuits’ approach, cases survive more easily and proceed to trial even when experts cannot pinpoint the precise cause that led to the plaintiff’s injury. The less rigid approach of these courts relaxes the gatekeeping need for causation experts, and as a result could lower standards too much, potentially exposing manufacturers and defendants to excessive liability.

Conclusion

These three decisions collectively illustrate how appellate courts can converge in evidentiary analysis yet diverge dramatically in outcome. For litigants on both sides of products liability cases, the forum matters: in some circuits, exclusion of causation experts ends the litigation; in others, it merely shapes the presentation of evidence to the jury. These cases highlight the heightened risk to manufacturers and defendants in the Third and Sixth circuits.

What remains clear is that these cases will continue to play a central role in the evolving boundaries of expert testimony in products liability law.

Erik Sardiña is a commercial litigation partner in the Hackensack, New Jersey office of Kaufman Dolowich. He serves as general outside counsel handling complex commercial matters in state and federal courts. He advises business clients throughout a myriad industries litigating and resolving business and corporate conflicts, directors’ and officers’ liability, and advising companies and executives on general legal issues, corporate governance, FDA, FTC, USDA, CBP compliance, including products liability defense. He can be reached at esardina@kaufmandolowich.com.

Eileen Ficaro is a partner in the Philadelphia office of the firm. She focuses her practice on professional liability defense, employment and commercial matters for clients across a broad spectrum of industries. She can be reached at eficaro@kaufmandolowich.com.

Reprinted with permission from the Nov. 25, 2025 edition of “Legal Intelligencer” © 2025 ALM Global Properties, LLC. All rights reserved. Further duplication without permission is prohibited, contact 877- 256-2472 or reprints@alm.com.