2) The Duty to Warn

Manufacturers are also under a duty to warn consumers of dangers inherent in the use of their products. The leading decision on the duty to warn is that of the Supreme Court in Lambert v. Lastoplex Chemicals Co. [Note 5: (1971), [1972] 2 S.C.R. 569 [Lambert].] In that case, the plaintiff was using a highly volatile and inflam-mable lacquer sealer to seal his basement floor. Writing on the can warned of the danger of using the product near an open flame but it did not direct the plaintiff to extinguish all pilot lights, the very peril overlooked by the plaintiff. The open can of sealer exploded when fumes were ignited by a pilot light. The plaintiff was injured. The product was not defective. Nevertheless, the Supreme Court found the defendant manufacturer liable because the warnings provided were insufficient to allow the product to be used safely. It held that a duty to warn arises where the product is placed on the market for use by the general public, the product is dangerous when used for its intended purpose, the manufacturer knows or ought to know of the danger, and the public does not have the same awareness of the danger as the manufacturer. [Note 6: This duty to warn also rests on others involved in the production and distribution of products who know or ought to know of the product's inherent dangers.]

The applicable standard of care is to take reasonable steps to provide warnings that permit the product to be used safely. The nature and extent of the warning required depends upon all the surrounding circumstances. Consideration is given to the nature and degree of the danger, the size, distinctiveness, intensity, clarity, and extent of any written warning, and the practice of the manufacturers of similar products. Attention is also paid to whether the warning is on the product itself, on the packaging, or in accompanying literature. What is reasonable depends in part on the nature of the product, the manner in which the product is marketed, commercial practice, and the habits of reasonable consumers. Compliance with statutory rules and regulations pertaining to the safety of products may not be sufficient to discharge the common law duty to warn. In Lambert, the Supreme Court held that compliance with the statutory standards did not sufficiently protect the plaintiff from the known risk of pilot lights.

Some product dangers do become sufficiently well known to the general public to permit manufacturers to dispense with warnings. There is no need, for example, to warn of the danger of knives, gasoline, hammers, or matches. It may reasonably be assumed that consumers fully appreciate and assume the risk arising from the use of such products. There is, however, good reason to continue warnings on many familiar products such as aerosol cans, domestic cleaning products, and small electrical appliances because consumers may not have complete knowledge or a reliable memory of all the risks. Furthermore, there is always someone such as a young adult, an immigrant, or a tourist who is using the product for the first time.

Generally, there is no need to warn of dangers arising from the abuse of products unless the defendant knows or ought to know that there is some history of abuse of the product by a segment of the public or if abuse of the product may reasonably be anticipated. Furthermore, knowledge that the particular product is going to be used by a purchaser in an improper and dangerous way may oblige a retailer to refuse to sell it to that person. This situation arose in a case where the purchaser expressed a determination to use the wrong tires on his gravel truck. [Note 7: Good-Wear Treaders v. D. & B. Holdings Ltd. (1979), 31 N.S.R. (2d) 380 (S.C.A.D.).] The retailer, who nevertheless sold them to the owner of the truck, was held liable for the death of innocent users of the highway who were hit by the truck when the tires blew out. The Court held that the defendant retailer ought not to have sold the tires. The issue may also arise in respect of the sale of solvents or glue to a known or suspected abuser of the product.

Less detailed warnings may be required where products are supplied for professional, commercial, or industrial purposes. The users of these products often have greater expertise and knowledge of the product than members of the general public. Much will depend upon the length of time that the product has been on the market, the extent of knowledge and use of the product in the particular trade or industry, the feasibility of warnings, and the practice of other manufacturers.

Causation is often a crucial element in duty to warn cases. The plaintiff must establish that he would have read and complied with a warning had it been given. If the product was used by the plaintiff without checking it for instructions or warnings, the accident would have happened even if a warning had been given and cause-in-fact cannot be established.

The manufacturer's duty to warn does not terminate on the sale of the product. It is a continuing one that requires the manufacturer to warn the consumer of inherent risks and dangers that are discovered after the product is on the market. Warnings must also be given of manufacturing defects and design flaws when they become known to the manufacturer. The manner in which the warning is given depends upon the product, the number in circulation, and the power to locate and contact the consumers. [Note 8: The situation that the public is most familiar with is the recall of automobiles with defects that come to light after the automobile is released onto the market.]

a) Medical Products and the Learned Intermediary Rule

The Lambert principle is equally applicable to the manufacturers of medical products such as pacemakers, heart valves, breast implants, artificial joints, and prescription drugs, and to the suppliers of biological products such as blood and semen. Manufacturers and suppliers of these products are under a heavy obligation to provide clear, complete, and current information concerning the dangers inherent in the ordinary use of these products. There are, however, obstacles to the direct communication of that information to patients. These products are normally provided to health-care professionals, and there is no practical way for the manufacturer to inform the individual patient.

The Supreme Court had an opportunity to address this issue in Hollis v. Dow Corning Corp. [Note 9: 1 [1995] 4 S.C.R. 634 [Hollis].] In that case, the plaintiff sued the defendant manufacturer in respect of a silicone breast implant that had ruptured and caused her damage. The crux of her case in the Supreme Court was that the manufacturer had failed to inform her or her physician of a small but known risk that the implant could rupture from normal, everyday activity. The Court recognized the obstacles to direct communication between the manufacturer and the patient and the primary reliance of the patient on her physician and held that it was sufficient for the manufacturer to provide the requisite information to a learned intermediary (normally the attending physician) who is then in a position to pass it on to the patient. The Court stated that disclosure could be made to a learned intermediary where a product is highly technical in nature and is intended to be used only under the supervision of experts (e.g., breast implants, artificial joints, and pacemakers) or where the nature of the product is such that the consumer will not realistically receive a direct warning from the manufacturer before using the product (e.g., prescription drugs). [Note 10: Ibid. at 660.] In the circumstances of the Hollis case, the manufacturer had not informed the learned intermediary of a material risk of rupture. The physician was not, therefore, in a position to tell the patient and the defendant was liable.

The Court also addressed two further issues arising in the Hollis case. Both related to aspects of the proof of causation.

The first dealt with establishing that the plaintiff would have declined to have had the breast implant surgery if she had been told of the material risk of rupture. If the plaintiff would have agreed to proceed with the implant surgery with knowledge of the risk of rupture, the defendant's fault was not a cause-in-fact of the plaintiff's loss. The contentious issue was the choice between the modified objective test, which would ask what a reasonable person in the plaintiff's position would have done if she had known of the risks, and a subjective test which would ask what the individual plaintiff would have done. A majority of the Court chose a subjective test and concluded that the plaintiff would not have had the implant surgery if she had been given appropriate warnings.

The second issue dealt with the lack of evidence in Hollis that the learned intermediary, the plaintiff's attending surgeon, would have passed on information about the risks of the implant rupturing to the plaintiff if it had been provided to him by the defendant. The defendant argued that such proof was essential to the plaintiff's case. Without it, cause-in-fact was not established. However, a majority of the Court held that it was not necessary to delve into such a hypothetical question and the defendant manufacturer could not exonerate itself on the ground that the physician might have been delinquent in his duty of disclosure. [Note 11: A physician must disclose the material risks of treatment to her patient under the doctrine of informed consent to medical treatment, which is discussed later in this chapter.] To hold otherwise could lead to the anomalous result of the manufacturer escaping responsibility on the ground that the learned intermediary would not have passed on the information to the patient and the learned intermediary escaping responsibility on the ground that she was not given the information by the manufacturer. The majority's decision on this point may also be justified on the ground that a manufacturer, who is given the convenience and indulgence of giving information to the learned intermediary rather than the consumer, must accept the risk of the learned intermediary defaulting on his obligation. Nevertheless, it does appear that the policies of deterrence and loss distribution have trumped the conventional need for the proof of cause-in-fact. [Note 12: This principle has been applied in Walker Estate v. York Finch General Hospital (1999), 43 O.R. (3d) 461 (C.A.). The defendant Red Cross was found negligent in their screening procedures of blood donors at high risk of carrying HIV, including the donor whose blood infected Ms. Walker. The issue was whether the estate of Ms. Walker carried the further burden of proving that the donor would have been deterred from giving blood if the appropriate screening measures had been in place. The Court applied Hollis and held that the plaintiff did not have to prove that hypothetical. It was not open to the defendant to prove that the precautions would have been ineffective. The Court was influenced by the innocence of the deceased, her reliance on the blood supply, and the difficulty in many cases of proving what third persons would have done.]

The learned intermediary rule does not apply to all medical products. Sometimes the manufacturer can give information and warnings directly to the consumer. This is the case with over-the-counter medications and some prescription medications such as oral contraceptives. The packaging of oral contraceptives, their long-term usage, the influence of socio-economic factors in deciding to use them, and, in some cases, the limited ongoing medical involvement and supervision of the patient by the prescribing physician, all support the desirability of direct warnings from the manufacturer. [Note 13: See Buchan v. Ortho Pharmaceuticals (Canada) Ltd. (1986), 54 O.R. (2d) 92 (C.A.).] The packaging and marketing of other prescription medications, such as inhalants, also facilitate direct communication of information to the consumer.