The Ninth Circuit Court of Appeals recently held that a Taser manufacturer had no duty to warn of the risk that repeated shocks administered by its products could lead to death caused by metabolic acidosis, given the state of the art at the time the product was manufactured. (Rosa v. Taser International, Inc., -- F.3d --, 2012 WL 2775006 (Cal.), July 10, 2012).

In Rosa, the plaintiffs’ decedent died after being administered a number of electric shocks by police officers applying their Tasers in an attempt to control him. The autopsy report stated that the cause of death was ventricular arrhythmia caused by methamphetamine intoxication, with “Taser application and arrest by police” listed as contributing conditions. The death was later linked to metabolic acidosis, a condition of increased lactic acid, which increases the risk of cardiac arrest.

The decedent’s parents sued the manufacturer of the Taser under theories of both strict products liability and negligence, arguing that the manufacturer had a duty to warn the police officers of the specific dangers of the product. In opposing the manufacturer’s motion for summary judgment, the plaintiffs argued that the manufacturer had a broad duty to warn of risks even if those risks were unsubstantiated in the medical and scientific literature or based on isolated case reports. In upholding the trial court’s granting of the motion, the Ninth Circuit rejected the plaintiffs’ overly broad characterization of the manufacturer’s duty to warn. The court noted that, under California law, a manufacturer had a duty to warn of a particular risk if the risk was known or “knowable in light of generally recognized and prevailing best scientific and medical knowledge available at the time of manufacture and distributing.” The court also stated that a manufacturer was required to keep up with scientific discoveries and would be presumed to know of any advances in knowledge concerning hazards posed by its products.

Here, however, the court found that there was no issue of triable fact that the risk of metabolic acidosis was known or knowable when the product was manufactured or supplied, stating that a manufacturer does not have a duty to warn based on “speculative, conjectural or tentative” reports of possible risks. The court rejected the plaintiffs’ reliance on a 2001 article published in the prestigious English medical journal The Lancet. The court pointed out that the authors of the study, while finding previous attempts to explain “in-custody death syndrome” to be unsatisfactory, “hypothesized” that such deaths could be caused by electronic control devices affecting the body’s acid-base balance. The court held that mere hypothesis, rather than firm conclusions based on adequate evidence, could not give rise to a duty to warn under California law.

The court also rejected a second study by the Department of Defense on the grounds that the study did nothing more than speculate as to a causal connection between use of Tasers and death caused by metabolic acidosis, rather than establishing a causal link. Noting that this study was published after the decedent’s death, the court noted that, under California law, a manufacturer may be liable in negligence under some circumstances for a failure to warn of a risk that became known only after the injury. However, this study (like the first) merely stated an untested hypothesis and thus could not support a finding that a reasonable manufacturer would have issued a supplemental warning.

The court’s opinion in Rosa was closely tied to the specific facts regarding the state of knowledge concerning the risks of metabolic acidosis posed by electronic control devices such as Tasers. However, the case suggests more generally that the court will reject a broad reading of a manufacturer’s duty to warn and will look closely into what was actually knowable at the time the product was manufactured or, alternatively, at the time of injury. The opinion is therefore favorable for products manufacturers raising a defense based on the state of the art concerning specific risks allegedly posed by their products.