Expert Witness Blog
Davis v. Sig Sauer, Inc.
A recent legal case involving an Ergonomics Expert Witness is Davis v. Sig Sauer, Inc., decided by the United States Court of Appeals for the Sixth Circuit in January 2025. The case citation is Davis v. Sig Sauer, Inc., No. 24-5210 (6th Cir. 2025).
Background and Parties
The plaintiff, Timothy Davis, accidentally shot himself in the leg with a Sig Sauer P320 X-Carry pistol while exiting his truck. Davis alleged that the firearm was defectively designed, causing it to discharge without the trigger being pulled. He brought a products liability action against Sig Sauer, Inc., asserting claims of strict liability and negligence under Kentucky law. Davis contended that the pistol’s design made it unreasonably dangerous and that feasible alternative designs could have prevented his injury.
Role and Methods of the Ergonomics Expert Witness
Davis retained two expert witnesses: James Tertin and Dr. William J. Vigilante, Jr. Dr. Vigilante is a human factors and ergonomics expert. His role was to analyze the design of the P320 pistol from an ergonomics and human factors perspective, focusing on how the design could contribute to unintentional discharges. Dr. Vigilante’s methodology included reviewing the pistol’s design features, evaluating accident reports, and considering the interaction between the user and the firearm. He opined that the P320’s design lacked adequate safety features and that alternative designs—such as a trigger safety or a manual safety—would have reduced the risk of accidental discharge.
Court’s Reliability and Daubert Analysis
The district court initially excluded the testimony of both experts regarding causation, finding that neither had investigated the specific circumstances of Davis’s shooting and thus could not reliably opine on what caused the gun to fire. The court also excluded their opinions on design defect and reasonable alternative designs, concluding that their methodologies were not sufficiently reliable under the standards set forth in Daubert v. Merrell Dow Pharmaceuticals, Inc. and Federal Rule of Evidence 702.
On appeal, the Sixth Circuit conducted a detailed analysis of the admissibility of the expert testimony. The appellate court agreed that the experts’ opinions on causation were properly excluded, as they had not examined the actual firearm or the precise circumstances of the incident. However, the court found that the district court erred in excluding the experts’ opinions on design defect and reasonable alternative designs. The appellate court held that Dr. Vigilante’s expertise in ergonomics and human factors, combined with his review of the pistol’s design and relevant literature, provided a reliable basis for his opinions on whether the P320 was defectively designed and whether safer alternative designs were feasible.
The Sixth Circuit emphasized that the Daubert standard is flexible and that the reliability of an expert’s methodology must be assessed in light of the specific facts of the case. The court concluded that Dr. Vigilante’s testimony was relevant and reliable for the purpose of establishing the existence of a design defect and the availability of safer alternatives, even if he could not opine on the precise cause of Davis’s injury.
Impact of the Expert Testimony on the Outcome
The exclusion of the experts’ causation testimony was affirmed, meaning Davis could not proceed on the theory that the design defect caused his specific injury without further evidence. However, the appellate court reversed the exclusion of the design defect and alternative design opinions, allowing Davis to present these aspects of his case to a jury. The court’s decision clarified the scope of admissible expert testimony in product liability cases involving ergonomics and human factors, reinforcing that such testimony is critical in evaluating whether a product’s design is unreasonably dangerous and whether safer alternatives exist.
This case illustrates the significant role an ergonomics expert can play in product liability litigation, particularly in analyzing design safety and human interaction with consumer products. The court’s nuanced application of Daubert standards underscores the importance of distinguishing between causation and defect analysis in expert testimony, and it affirms the admissibility of well-founded ergonomics opinions in federal courts.