A group of firefighters claiming a siren damaged their hearing failed to provide enough evidence to show that a proposed alternative design was actually safer, the Pennsylvania Superior Court has ruled in an opinion that sheds light on how courts are treating the intersection of expert testimony and industry standard evidence in the wake of the seminal 2014 decision Tincher v. Omega Flex.

A split three-judge panel issued a precedential decision Aug. 20 in Dunlap v. Federal Signal saying the plaintiffs needed to have an expert testify that their proposed alternative design was safer than the sirens the defendants made, and that simply relying on the fact that the proposed design met industry standards was insufficient to allow the case to go forward.