Sig Sauer Gun Defect Appeal Focuses on Need for Expert Testimony

Counsel for Sig Sauer Inc. tried to convince a federal appeals court panel Wednesday that expert testimony is required to prove that a gun defect caused an unintentional firing and subsequent injury.

Immigration and Customs Enforcement officer Keith Slatowski sued the firearms manufacturer after his P320 gun unintentionally went off and injured him during a training drill. The district court granted summary judgment to Sig Sauer after determining Slatowski’s experts didn’t say what could have caused the accidental firing. The trial court also rejected Slatowski’s argument that causation was a factual question for a jury to decide.

The gun in this case was holstered, and the jury doesn’t have enough information to know whether the trigger could have been disengaged by the holster, said Kristen Dennison of Littleton Joyce Ughetta & Kelly LLP, who represented the gun maker at oral arguments. Slatowksi’s experts failed to consider the holster in their testimony, so he couldn’t show causation, she told the US Court of Appeals for the Third Circuit.

“The thrust of your argument is that you can never have product liability without an expert who was at the scene or immediately thereafter,” Judge Stephanos Bibas said to Dennison. But “sometimes you can just infer it from the accident, and the upshot of your position is going to make it quite possible for lots of defective products to escape any liability,” he said.

Dennison replied that Sig Sauer’s argument isn’t that an expert needs to have been at the accident. But the expert needs to speak to specific measurements of force from a foreign object like a holster that could cause the gun to discharge, compared to a defect in the product itself, she said. Slatowski’s experts didn’t do that, Dennison said.

Robert Zimmerman of Saltz Mongeluzzi Bendesky PC, who represented Slatowski, said the officer did testify about the type of holster he was wearing. The primary issue here isn’t about expert testimony, but whether the case was too complex for a jury, he said.

Slatowski’s suit is similar to a Sixth Circuit case involving the same gun, where that appeals court held that the issue of causation could go to the jury.

But Dennison argued that without an expert’s analysis of the holster, which she said didn’t cover the entire gun, the information the jury received would be incomplete and they would have to guess about causation.

“Why is this something that needs expert testimony? Why can’t this just be taken as lay knowledge and common sense of the jury to look at the whole story and how much it covers just as you’re not an expert and you’re describing it to us?” Bibas asked her.

Dennison said a jury needed to understand how a foreign object like the holster could interact with the trigger and cause an unintentional firing—and that an expert should explain that.

Judge Tamika R. Montgomery-Reeves, who echoed Bibas’ question, also asked why an expert was needed to discuss those possibilities.

Judge Cheryl Ann Krause also sat on the panel.

The case is Slatowski v. Sig Sauer Inc., 3d Cir., No. 24-01639, oral arguments held 4/30/25.