The Ninth Circuit has provided product manufacturers some potent ammunition in their ongoing efforts to keep hindsight bias from infecting the scope of their constructive knowledge in failure-to-warn claims. In defending such claims, manufacturers often struggle to define what risks associated with their products were “knowable” from the scientific literature (and thus within the scope of their constructive knowledge) at the time their products allegedly caused injury. Plaintiffs attempt to compound this difficulty by presenting pre-injury scientific literature that does not address the product – or even the injury – at issue, but instead vaguely pertains to the product’s mechanism or the injury’s pathology. Their experts then rely on hindsight in opining that the manufacturer should have “put the pieces together” to draw a causal conclusion the scientific literature only reached later.

This tactic renders the Ninth Circuit’s recent opinion in Rosa v. TASER Int’l [pdf] a welcome development for product manufacturers, particularly those litigating in California. — F.3d —, 2012 WL 2775006 (9th Cir. Jul. 10, 2012). In affirming summary judgment in favor of TASER, the Court held that scientific articles that do not link their findings regarding the injury at issue to the product at issue are not sufficient to constitute constructive knowledge that the product could cause that injury. Neither are articles that actually do associate the injury with the product, but as an untested hypothesis – especially if they are not publicly-available. Indeed, Rosa strongly suggests that only articles that are publicly available prior to the alleged injury and articulate a scientifically-validated causal link between a manufacturer’s product and the plaintiff’s injury will trigger the manufacturer’s duty to warn of that injury. By insisting that a manufacturer’s constructive knowledge is only informed by scientific literature that explicitly and concretely links its product to the plaintiff’s injury, the Ninth Circuit has essentially foreclosed plaintiffs’ tactic of importing hindsight bias into their interpretation of the relevant literature.