The California Supreme Court recently expanded potential defenses for manufacturers who are alleged to have failed to warn about risks associated with their products. In Johnson v. American Standard, 179 P.3d 905, 74 Cal.Rptr.3d 108 (Cal. 4/3/08), the Court adopted the so-called “sophisticated user” doctrine, holding that a manufacturer has no duty to provide warnings to plaintiffs who should already be aware of product hazards because of their professional training or expertise.

Part of the analysis of a duty to warn claim is the identity of the person to whom a duty to warn may be owed. A second part of the analysis, assuming a duty exists, is whether a failure to warn can be the legal cause of the injury alleged. Two important doctrines affect this analysis.

  • One is the so-called bulk supplier doctrine. In many contexts, a chain of commerce exists in which the manufacturer may not be in privity with end users or consumers. As explored in Section 388 of the Second Restatement of Torts, comment n, does a supplier exercise due care by fully warning his immediate customer, and entrusting the communication of the necessary information to users farther down the chain? Courts have generally focused on a number of factors in deciding whether the upstream supplier is reasonable in so doing. First, what are the burdens involved in requiring the manufacturer or ultimate supplier to directly warn the end users? Second, how reliable is the intermediate, the employer, the intermediate purchaser, as a conduit for the necessary information to the downstream user? And third, what is the magnitude of the risks involved, balanced against those burdens?

    In a number of product contexts, it is very difficult for the supplier to reach the end user directly. The manufacturer may not know who the end users are. The supplier may not have a practical means of reaching the end users with warning information because of the nature of the product and how it is shipped. Thus, a number of cases in this area are “bulk supplier” cases in which he chemical or other product is sold or delivered in bulk and then repackaged in other containers by the intermediate users; the original containers which might have warning information never reach the end users. The product might be combined with other products sold by others. The product might be unloaded, conveyed or stored in a manner such as to defeat any original warnings. The nature of the warning may be such that only the end user can take appropriate precautions for safe use. The existence of numerous suppliers may potentially confuse the information flow. Safety may not be enhanced by requiring the manufacturer to do more than warn the immediate customer. Purvis v. PPG Industries, 502 So.2d 714 (Ala. 1987); Adams v. Union Carbide, 737 F.2d 1453 (6th Cir. 1984). Many courts apply the same notion to strict liability warnings cases. E.g., Smith v. Walter C. Best, Inc., 927 F.2d 736 (3d Cir. 1990). Of course, is some product contexts, regulations impact the duty, such as the Material Safety Data Sheet (MSDS) that must accompany certain hazardous chemicals, and must be made available by employers to employees potentially exposed to those chemicals in the workplace.


  • The second related notion arises when those downstream users are themselves expert in the safe handling and use of the product, perhaps even as knowledgeable as the original manufacturer. This raises the sophisticated user doctrine.

Background of the Decision

The California opinion involved a suit brought by an air conditioning technician who suffered from lung disease (pulmonary fibrosis) allegedly caused by exposure to phosgene gas. Plaintiff Johnson alleged the defendant knew that phosgene gas can cause a potentially fatal lung disease, and would be released when evaporators were serviced. The defendant allegedly failed to provide adequate warnings about the hazard. Plaintiff was a certified HVAC technician who alleged he was exposed to phosgene gas while welding in the course of repairing an air conditioning unit made by the defendant. Phosgene gas is formed when R-22, a hydrochlorofluorocarbon refrigerant, is exposed to flame or high heat. The plaintiff had gone to trade school where he was allegedly trained in the risks of toxic exposure during welding, received a study guide for a certification exam offered by the EPA that addressed those risks, and passed a five-part test to obtain the EPA’s highest level of certification. That certification was mandatory for any technician to work on commercial air conditioning systems. Whenever the plaintiff purchased refrigerant for those systems, he was supposed to have received an MSDS advising of the risk, and his employer was also required to provide him with job training addressing those risks.

In addition, expert testimony established that the specific health risks associated with inhaling heated refrigerant were widely known in the profession.  American Standard also argued that it was widely known by industry technicians that R-22, when heated, can decompose into toxic byproducts including phosgene. The Environmental Protection Agency requires HVAC professionals to understand decomposition products of refrigerants at high temperatures, the defendant argued. 74 Cal.Rptr.3d at 112-113.

Plaintiff’s Version

Johnson testified that although he read material data safety sheets every time he purchased the refrigerant, he did not understand that he should avoid heating it. In deposition, Johnson testified that he did not learn in training that phosgene gas could be created when refrigerant lines were brazed, or that phosgene could cause lung damage. He said he never heard of phosgene until he got sick. Although he read the MSDS for R-22, Johnson said he understood the warning about hot metal as a caution against heating metal, not against heating R-22. 74 Cal.Rptr.3d at 114, 122.

Sophisticated User Doctrine

The air conditioning equipment maker (other defendants had reportedly settled or been dismissed) raised the defense, arguing that the sophisticated user doctrine is specifically applied to plaintiffs who knew or should have known of a product’s hazards, and it acts as an exception to manufacturers’ general duty to warn consumers. That is, manufacturers generally have a duty to warn consumers about any dangers inherent in their products that the consumers would not know about, so that the consumers can either decide not to use the product or use it in ways that would avoid the stated dangers. The sophisticated user defense is an exception to this general rule, as users sufficiently familiar with the product already know or should know about the dangers that would be announced in any warning. Because these sophisticated users are charged with knowing the particular product’s dangers, the failure to warn about those dangers is not the legal cause of any harm that product may cause.

The trial court granted summary judgment on the basis of the doctrine, and the court of appeals affirmed. The state Supreme Court noted that the doctrine in most jurisdictions is treated as an affirmative defense to negate the manufacturer’s duty to warn, under the theory that sophisticated users need not be warned about dangers on which they are already aware or should be aware. Because the user is presumed to know the risk, the failure to warn of the danger cannot be the legal cause of the harm. The Court noted that the doctrine is a natural extension of the notion that there is no duty to warn of known risks or obvious dangers. For those individuals or members of professions who do or should know about the product’s potential dangers, those risks should be obvious. 74 Cal.Rptr.3d at 114-115.

In discussing the policy issues raised by the doctrine, the Court noted that “Not all warnings . . . promote user safety. Requiring manufacturers to warn their products’ users in all instances would place an onerous burden on them and would invite mass consumer disregard and ultimate contempt for the warning process.” 74 Cal.Rptr.3d at 119. The doctrine thus helps ensure that warnings will be heeded.

Clarification of the Doctrine

The opinion offers clarity on a number of features of the doctrine, which would apply “equally to strict liability and negligent failure to warn cases.”

  • First, Johnson makes clear that the test is an objective one that depends not on what the plaintiff subjectively knew about the risks, but rather what is generally known or should have been known to the relevant class of sophisticated users. It is virtually impossible for a manufacturer to predict – and of course warnings are by their very nature based on predictions about users – whether any given member of a trained and sophisticated group has actual knowledge of the dangers. A manufacturer’s liability does not depend on the potentially “infinite number of user idiosyncrasies” that may result in a particular user being unaware of the risk, such as users who “may have misread their training manuals, failed to study the information in those manuals, or simply forgotten what they were taught.” 74 Cal.Rptr.3d at 120. However, if individuals hold themselves out as having training or having professional knowledge and skill associated with that class of users, that they might not actually possess all that knowledge and skill does not give rise to liability on the part of the manufacturer.


  • Second, the Court found that user sophistication is measured from the time of the plaintiff’s injury, rather than from the date the product was manufactured or sold. This is consistent with the rule’s focus on the knowledge of the general population of sophisticated users rather than that of the manufacturer, and “conforms to the defense’s purpose to eliminate any duty to warn when the expected user population is generally aware of the risk at issue.” 74 Cal.Rptr.3d at 122.

    Although the case involved a trained, sophisticated plaintiff, the Court discussed with approval two cases which applied the doctrine to a context in which the manufacturer warned a sophisticated intermediary, which then sold the product to the plaintiff end user. In Fierro v. International Harvester Co., (1982) 127 Cal.App.3d 862, the plaintiff sued the defendant because it manufactured the truck her husband was driving when he crashed and died. The plaintiff’s husband was driving the truck in the course and scope of his employment when the truck overturned after blowing a tire, crashed, skidded for a distance, spilled fuel, and caught fire. The plaintiff alleged that the defendant had a duty to warn not her husband, but the purchaser (his employer), that attaching power cables from the refrigerator unit to the truck’s battery could create a fire hazard. The court found that the defendant was not liable for failing to warn the employer, explaining in dicta that the employer was a “sophisticated organization” that “does not have to be told” of the risks. Similarly, In re Related Asbestos Cases, 543 F.Supp. 1142 (N.D.Cal. 1982), applied the so-called “sophisticated intermediary” doctrine to the US Navy, which was a sophisticated user of asbestos products, and which then distributed them to employees for use.

    Finally, the opinion reserved for future decision the issue of whether a plaintiff will be able to negate the application of the sophisticated user defense by showing that the sophisticated user’s misuse of the product was foreseeable.

    The Product Liability Advisory Council