In American product liability litigation, there are two causation requirements: warnings causation and factual causation. The law imposes a duty to warn of risks, and the alleged failure to warn must have some connection with the plaintiff’s use of the product in such a way as to have caused him harm. If an adequate warning, whatever that is, would have protected plaintiff from the harm, then there is the requisite nexus between the alleged failure to warn and plaintiff’s harm.
The product must also, however, be a factual cause of the harm. For instance, a really scary warning that promised death and destruction might have kept the plaintiff from using the product, but still, the product itself must have caused the harm, for the plaintiff to satisfy the factual causation requirement.
The history of the last 50 years or so of American products liability law has been a narrative of unending assault on causation, both with respect to warnings causation, and to medical or factual causation. Plaintiffs have sought to dilute, eliminate, create presumptions for, and shift the burden of proof of, both causation requirements.
The duty to warn arises, understandably, when the seller or manufacturer has knowledge that the product can cause harm, and the buyer lacks this knowledge. For various reasons, sloppiness, ideology, or advocacy, some writers neglect the requirement that the buyer must lack the knowledge of the danger. Quod vanum et inutile est, lex non requirit. The law does not require what is vain and useless. This principle of equity and law still informs the law of product liability, through doctrines and rules such as sophisticated user and sophisticated intermediary.
The duty to warn was traditionally couched in terms of a duty to impart knowledge, actual or constructive, or a connection between a foreseeable use of the product and a serious harm. The plaintiffs’ bar’s war on causation has sought to lower the epistemic standard for both warning and factual causation. There are too many cases to cite for the proposition that sellers must warn of potential risks as well as actually known or knowable risks. This erosion would be harmless but for the similar erosion in standards of medical or factual causation, and the attempts to abandon meaningful standards of expert witness causation opinions.
It is thus refreshing to see the Ninth Circuit hold that California’s law of duty to warn applies to only to known or knowable risks. Last year, the Court of Appeals held that a Taser manufacturer had no duty to warn of the risk that repeated shocks administered by its products could lead to death by inducing metabolic acidosis, given the state of the art at the time the product was manufactured. In Rosa v. Taser International, Inc., 684 F.3d 941 (9th Cir. 2012) , the Rosa’s son died after being “tased” by police officers. The autopsy report attributed death to ventricular arrhythmia, caused by Michael Rosa’s having used methamphetamine, along with the police’s use of Tasers. Expert witnesses postulated the mechanism of causation between tasing and death was metabolic acidosis, which consists of increased lactic acid levels, which in turn increased the risk of cardiac arrest.
The Rosas sued Taser International, Inc., the manufacturer of the “stun guns” on theories of strict liability and negligent failure to warn the purchasers, the police, of the dangers of the product. (They did not sue the meth manufacturer or retailer.) The Rosas argued that Taser had a duty to warn of any risk, “no matter how unsubstantiated,” even if based upon speculative or conjectural statements, or inadequate studies. Id. at 946. The Court Appeals decisively rejected a duty to warn on this inconclusive evidentiary display.
The Ninth Circuit held that California law conditions the duty to warn on a high epistemic standard of knowledge, actual or constructive. Id. at 946. The manufacturer must warn of a “particular risk … known or knowable in light of the generally recognized and prevailing best scientific and medical knowledge available at the time of manufacture and distribution.” Id. (quoting from Conte v. Wyeth, Inc., 168 Cal.App.4th 89, 85 Cal.Rptr.3d 299, 310 (2008) (emphasis added by the Circuit Court).
Noting that the California courts have not articulated epistemological principles for knowledge of hazards that must find their way into warnings, the court, in Rosa, noted some accepted considerations. First, ignorance is not a defense. ‘‘[A] manufacturer is held to the knowledge and skill of an expert in the field; it is obliged to keep abreast of any scientific discoveries and is presumed to know the results of all such advances.’’ Id. at 946 (citing Carlin v. Superior Court, 13 Cal.4th 1104, 56 Cal. Rptr.2d 162, 920 P.2d 1347, 1351 n. 3 (1996)).
Second, a manufacturer need not warn of “every report of a possible risk, no matter how speculative, conjectural, or tentative.” Id. (internal citations omitted). A duty to warn of every possible risk would have the counter-productive result of diluting the effect of specific warnings of real risks, by “inundat[ing the public] indiscriminately with notice of any and every hint of danger.” Id.
The Rosas relied upon four peer-reviewed articles to argue that Taser had a duty to warn. Id. at 497. The Ninth Circuit looked past the fact of mere publication and peer review, to the actual nature and content of the relied-upon articles. Some of the publications did not address stun guns, but two did, although in speculative ways. See Raymond Fish & Leslie A. Geddes, “Effects of Stun Guns and Tasers,” 358 The Lancet 687 (2001). The second publication was a Department of Defense report, which predated Michael Rosa’s death, but was not generally available until after his death. John M. Kenny, et al., Human Effects Advisory Panel, Report of Findings Sticky Shocker Assessment (1999). The court doubted whether such a report, unavailable to defendant, could be the predicate for defendant’s duty warn. In any event, the content of the 1999 report was itself speculative, and merely concluded that “deaths following Taser[] use may be due to acidosis.” Kenny at 31. The report did not state a causal conclusion, and it qualified its dataset as limited by small size. Kenny at 32.
Taser added relevant warnings, six years after Michael Rosa’s death, and the Rosas sought to capitalize upon the warnings as admissions of some sort. Id. at 948. The Court of Appeals rebuffed this argument, not only on the basis of subsequent remedial measure, but also on the basis of “state of the art,” which requires that the evidence of the harm, which forms the basis for the duty to warn, be known or knowable at the time of marketing of the product. Id.
In Rosa, the available evidence that might constitute “knowledge” of a harm shifted between the time of injury, and the time of litigation. In latent disease litigation, the shift in evidence can be extreme, and hence the importance of “state of the art” as a limit to the duty to warn.
Can the evidence for a knowledge claim regress? If what was in the medical literature at some earlier time turned out to be false later, then it would seem that it was never “knowledge” in the first place. Still, plaintiffs would likely rely upon the older apparent knowledge to claim that it created a duty to warn. For instance, in asbestos litigation, plaintiffs have claimed, since the late 1970s, that asbestos exposure causes gastrointestinal (GI) cancer. The plaintiffs’ claims were supported by Dr. Selikoff and his cadre of Mt. Sinai testifying physicians and scientists, and many textbooks and review articles stated, without qualification, that asbestos caused GI cancer. In 2006, however, the Institutes of Medicine convened a committee to review non-pulmonary cancers and asbestos, and concluded that the studies, accumulated over 35 years since Dr. Selikoff’s ipse dixit, did not support a conclusion that asbestos causes colorectal cancer. Institute of Medicine of the National Academies, Asbestos: Selected Health Effects (2006). If the claim is unsupported in 2006, it was not established at times past, despite the assertions of plaintiffs and their partisan expert witnesses in litigation, and in publications.
Another example of the uneven path of knowledge is the claim that silica causes lung cancer. Early writers suggested this hypothesis on the basis of flawed evidence, but the claim came to be rejected when astute authors realized that the lung cancer mortality experience of uranium miners was determined by their exposure to ionizing radiation, not to silica. Starting in the 1980s, however, a group of advocate scientists started to press for recognition of silica itself as a lung carcinogen, and these scientists narrowly succeeded, by a deeply divided vote, in an IARC working group vote in 1996. This IARC classification put crystalline silica into category I, but the rationale for this classification was soon thereafter shown to be lacking. See Patrick A. Hessel, John F. Gamble, J. Bernard L. Gee, Graham Gibbs, Francis H.Y. Green, W. Keith C. Morgan, and Brooke T. Mossman, “Silica, Silicosis, and Lung Cancer: A Response to a Recent Working Group Report,” 42 J. Occup. Envt’l Med. 704 (2000). A seller of crystalline silica should, under the Rosa case, be well within its rights not to warn of a risk of lung cancer. The reality is that the litigation system is way too uncertain and even capricious, leading most companies to have warned of lung cancer “risk” from the mid-1980s, forward.
What is encouraging about Rosa is its implicit recognition that the Rule 702 factors for reliable scientific opinion are very much in play when evaluating historical scientific opinion, which is asserted to be the basis for a duty to warn. The more typical “state of the art” decisions simply pass over validity and reliability of historical statements and conclusions, with a grand gesture that everything published serves to provide “notice” of a potential hazard. This usual approach begs the question, however, whether there was a sound basis for a conclusion that the product was known to cause the harm alleged in the pending case. The scientific nature of the historical determination may mean that historians, lacking in scientific credentials, will be inappropriate witnesses to support historical claims of knowledge of risks. The Rosa court’s insistence upon historical study and conclusion validity and correctness requires a careful review of the historical epistemic claim in view of the full historical and contemporary record.
In the Rosa case itself, the claim of failure to warn failed as a result of a fair analysis of the extant evidence for the claim at the time of marketing of the Taser. The post-marketing shift in the epistemic basis for the failure-to-warn claim was irrelevant to the Rosas’ case. Perhaps the warnings vel non on the methamphetamine used by Michael Rosa would have been a better predicate for the lawsuit?
