MEMO TO:
Alexsei Demo
RESEARCH ID:
#40006561fe475d
JURISDICTION:
Ontario, Canada
ANSWERED ON:
March 15, 2022

Issue:

What's the test for negligent design in product liability cases?

Facts:

A manufacturer of hoverboards discovers that if their hoverboards were charged on a 35 degree angle on quartz, a reaction would occur leading to a battery fire. The manufacturer contacted consumers to alert them to the risk and how to reduce it. Because it's such a specific issue and is so unlikely to occur, a decision is made not to recall the hoverboards. The plaintiff, an owner of such hoverboards, never gets the e-mail (it goes to spam). Eventually, he charges his hoverboard on his quart countertop because he runs out of space on the floor. While it charges, it tilts to a 35 degree angle and catches fire, immolating his residence. He makes it out alive - just.

Conclusion:

For products liability claims, there are four established categories. First, manufacturers have a duty of care to consumers to see that there are no defects in manufacture that are likely to give rise to injury in the ordinary course of use. Second, manufacturers have a duty of care to warn consumers of dangers inherent in the use of the product of which the manufacturer has knowledge or ought to have knowledge. Third, manufacturers have a duty of care in designing the product to avoid safety risks and to make the product reasonably safe for its intended purposes. Fourth, there is a pure economic loss claim in negligence because manufacturers have a duty of care to compensate consumers for the cost of repairing a dangerous product that presents a real and substantial danger to the public. (Vester v Boston Scientific Ltd.)

The analysis may begin by placing the negligence in design cause of action in the context of products liability claims generally, for which there are four established genres. First, manufacturers have a duty of care to consumers to see that there are no defects in manufacture that are likely to give rise to injury in the ordinary course of use. Second, manufacturers have a duty of care to warn consumers of dangers inherent in the use of the product of which the manufacturer has knowledge or ought to have knowledge. Third, manufacturers have a duty of care in designing the product to avoid safety risks and to make the product reasonably safe for its intended purposes. Fourth, there is a pure economic loss claim in negligence because manufacturers have a duty of care to compensate consumers for the cost of repairing a dangerous product that presents a real and substantial danger to the public. (Price v. Smith & Wesson Corp.)

The underlying argument in a design negligence action is that a manufacturer has a duty of care not to design a product negligently because the manufacturer should and can fairly be held responsible for the choices it makes that affect the safety of the product. The manufacturer has a duty to make reasonable [page709] efforts to reduce any risk to life and limb that may be inherent in its design. To succeed in a cause of action for negligent design of a product, the plaintiff must identify the design defect in the product and establish that the defect created a substantial likelihood of harm and that there is, safer and more economically feasible ways to manufacture the product. In the case of negligence in designing a product, the defendant is blameworthy for not designing its product in a safer manner. A manufacturer does not have the right to manufacture an inherently dangerous article when a method exists of manufacturing the same article without risk of harm. (Price v. Smith & Wesson Corp.)

The law does not require a manufacturer to produce articles that are accident proof or incapable of doing harm, but a manufacturer does have a duty to design a product that is not defective. Depending on the product, defectiveness may be determined in relation to the design of the product based on a risk-utility analysis of an alternative safer design of the product. In this category of products liability duty of care, whether a manufacturer breaches its duty is determined by a risk-utility analysis that measures whether the utility of the chosen design outweighs the foreseeable risks associated with the chosen design. In negligent design cases, the determination of whether a manufacturer breaches its duty of care in designing a product depends upon a risk-utility analysis that measures whether the utility of the chosen design outweighs the foreseeable risks associated with the chosen design. This risk-utility analysis requires weighing any foreseeable risk against the foreseeable utility of the product based on the information available to the manufacturer at the time of distribution or implantation and without the benefit of hindsight. Manufacturers are required to weigh the likelihood of both the benefit and the risk offered by a product as well as the value of the potential benefit and the seriousness of the potential risks. (Price v. Smith & Wesson Corp.)

In Rentway Canada Ltd./Ltée v. Laidlaw Transport Ltd., Granger J. compiled a list of factors to consider when balancing the risks inherent in the product, as designed, against its utility and cost, namely, (1) the utility of the product to the public as a whole and to the individual user; (2) the nature of the product -- that is, the likelihood that it will cause injury; (3) the availability of a safer design; (4) the potential for designing and manufacturing the product so that it is safer but remains functional and reasonably priced; (5) the ability of the plaintiff to have avoided injury by careful use of the product; (6) the degree of awareness of the potential danger of the product which reasonably can be attributed to the plaintiff; and (7) the manufacturer's ability to spread around any costs related to improving the safety of the design. (Price v. Smith & Wesson Corp., Rentway Canada Ltd./Ltée v. Laidlaw Transport Ltd.)

The principle embodied in the maxim res ipsa loquitur applies in an action resulting from the negligence of the defendant where it is shown that the thing which caused the accident was under the management of him or his servants, and that the accident was such as in the ordinary course of things would not have happened if proper care had been exercised by him or his servants. It is used in actions for negligence where no proof of negligence is required beyond the accident itself which is such as to involve a prima facie inference of negligence on the part of the defendant, e.g., in the case of a collision between two trains upon a defendant's railway system. It ought not to be applied to evidence of an unexplained accident, if the evidence is as consistent with the cause of the accident having been the victim's own negligence as with its having been that of the defendant. It is conceivable that there may be circumstances in which the rule might be invoked against the supplier or repairer of a motor-car, e.g., if a brake failure occurred immediately after the customer took delivery of the repaired vehicle.  (Phillips et al. v. Ford Motor Co. of Canada Ltd. et al.)

Law:

In Vester v Boston Scientific Ltd., 2015 ONSC 7950 (CanLII), the Court established the duty of care standard with regards to product liability claims: 

[5] For products liability claims, there are four established categories. First, manufacturers have a duty of care to consumers to see that there are no defects in manufacture that are likely to give rise to injury in the ordinary course of use: Donoghue v. Stevenson, 1932 CanLII 536 (FOREP), [1932] A.C. 562 (H.L.). Second, manufacturers have a duty of care to warn consumers of dangers inherent in the use of the product of which the manufacturer has knowledge or ought to have knowledge: Hollis v. Dow Corning Corp., 1995 CanLII 55 (SCC), [1995] 4 S.C.R. 634 at para. 20; Lambert v. Lastoplex Chemicals Co., 1971 CanLII 27 (SCC), [1972] S.C.R. 569 at p. 574; Bow Valley Husky (Bermuda) Ltd. v. Saint John Shipbuilding Ltd., 1997 CanLII 307 (SCC), [1997] 3 S.C.R. 1210. Third, manufacturers have a duty of care in designing the product to avoid safety risks and to make the product reasonably safe for its intended purposes: Ragoonanan v. Imperial Tobacco Canada Ltd. (2000), 2000 CanLII 22719 (ON SC), 51 O.R. (3d) 603 (S.C.J.); Rentway Canada Ltd. v. Laidlaw Transport Ltd., [1989] O.J. No. 786 (H.C.J.), aff'd [1994] O.J. No. 50 (C.A.). Fourth, there is a pure economic loss claim in negligence because manufacturers have a duty of care to compensate consumers for the cost of repairing a dangerous product that presents a real and substantial danger to the public: Winnipeg Condominium Corporation No. 36 v. Bird Construction Co. Ltd., 1995 CanLII 146 (SCC), [1995] 1 S.C.R. 85.

In Rentway Canada Ltd./Ltée v. Laidlaw Transport Ltd., 1989 CarswellOnt 23, [1989] O.J. No. 786 (Ont High Ct J), affirmed on appeal 1994 CarswellOnt 2790, [1994] O.J. No. 50 (ONCA), Granger J. set out the relevant principles relating to product liability cases involving defective design:

42 In most product liability cases defects are found which were not intended by the manufacturer. These include, among other things, foreign bodies, missing parts or faulty assembly. In such cases the law has evolved to assist plaintiffs who can show a defect but are unable to prove how and when the negligence occurred. In Ontario, it has been stated that there is an evidentiary presumption in favour of the plaintiff once a defect has been shown, and a corresponding evidentiary burden on the defendant to disprove negligence: Zeppa v. Coca Cola Ltd., [1955] O.R. 855, [1955] 5 D.L.R. 187 (C.A.); Brunski v. Dominion Stores Ltd. (1981), 20 C.C.L.T. 14 (Ont. H.C.).

43 Defective design actions involve a different analysis as the design is intended by the manufacturer and the plaintiff is not attempting to show that there was negligence in the production process. The manufacturer has a duty to make reasonable efforts to reduce any risk to life and limb that may be inherent in the design.

44 In Gallant v. Beitz (1983), 42 O.R. (2d) 86, 25 C.C.L.T. 81, 148 D.L.R. (3d) 522 (H.C.), Linden J. stated at 90 [O.R.]:

Hence, one must use care to design vehicles properly and one must also use care to minimize the harm that may result from accidents. The marriage of these two concepts leads logically to a principle of tort liability for negligently designing a vehicle that is not reasonably crashworthy. Since motor vehicle manufacturers know or should know that many of their vehicles will be involved in collisions and that many people will be injured in those crashes, they must turn their minds to this matter during the process of planning and the designs of their vehicles and they must employ reasonable efforts to reduce any risk to life and limb that may be inherent in the design of their products. The American courts have embraced this principle in numerous cases (Larsen v. General Motors Corp. (1968), 391 F. 2d. 495Dyson v. General Motors Corp.; Stephenson Third Party (1969), 298 F Supp. 1064; Prosser, Handbook of the Law of Torts, 4th ed. (1971), at p. 646) and I can see no reason why Canadian courts should adopt a different view. It is a sensible position, completely in harmony with the principles of Canadian tort law, the effect of which should stimulate greater efforts by motor vehicle producers to design safer vehicles: see Zarnett, 'Tort Liability for Defective Automobile Design', 13 Osgoode Hall L.J. 483 (1975).

Therefore, it is possible for an automobile manufacturer to be rendered liable if it fails to take reasonable care to design its products in a reasonable crashworthy manner. In this case, it will be for the trial court, after hearing all of the evidence, to determine whether Nissan should have been aware of the danger to passengers from these iron bars in its Datsun trucks and whether they took reasonable steps to combat the risk.

45 The American Courts appear to have settled on risk-utility approach in design defect actions.

46 In Prentis v. Yale Mfg. Co., 365, N.W.2d 176 (Mich., 1984) Boyle J. in dealing with a design defect stated at 183-184:

The approaches for determination of the meaning of 'defect' in design cases fall into four general categories. The first, usually associated with Dean Wade, employs a negligence risk-utility analysis, but focuses upon whether the manufacturer would be judged negligent if it had known of the product's dangerous condition at the time it was marketed. The second, associated with Dean Keeton, compares the risk and utility of the product at the time of trial. The third focuses on consumer expectations about the product. The fourth combines the risk-utility and consumer-expectation tests. While courts have included many other individual variations in their formulations, the overwhelming consensus among courts deciding defective design cases is in the use of some form of risk-utility analysis, either as an exclusive or alternative ground of liability. Risk-utility analysis in this context always involves assessment of the decisions made by manufacturers with respect to the design of their products.

The law purports to stand as a watch-dog to ensure that product design decisions made by manufacturers do not expose product users to unreasonable risk of injury. Thus, in a design defect case, the issue is whether the manufacturer properly weighted the alternatives and evaluated the trade-offs and thereby developed a reasonably safe product; the focus is unmistakably on the quality of the decision and whether the decision conforms to socially acceptable standards.

The risk-utility balancing test is merely a detailed version of Judge Learned Hand's negligence calculus. See United States v. Carroll Towing Co., 159 F.2d 169, 173 (C.A. 2, 1947). As Dean Prosser has pointed out, the liability of the manufacturer rests upon a departure from proper standards of care, so that the tort is essentially a matter of negligence.

Although many courts have insisted that the risk-utility tests they are applying are not negligence tests because their focus is on the product rather than the manufacturer's conduct, see, e.g. Barker v. Lull Engineering Co., Inc., 20 Cal.3d 413, 418, 143 Cal.Rptr. 225, 573 P.2d 443 (1978), the distinction on closer examination appears to be nothing more than semantic. As a common-sense matter, the jury weighs competing factors presented in evidence and reaches a conclusion about the judgment or decision (i.e., conduct) of the manufacturer. The underlying negligence calculus is inescapable. As noted by Professor Birnbaum:

When a jury decides that the risk of harm outweighs the utility of a particular design (that the product is not as safe as it should be) it is saying that in choosing the particular design and cost trade-offs, the manufacturer exposed the consumer to greater risk of danger than he should have. Conceptually and analytically, this approach bespeaks negligence.

Birnbaum, Unmasking the test for design defect: From negligence to warranty to strict liability to negligence, 38 Van.L.R. 593, 610 (1980) (quoting Barker v. Lull Engineering, supra, 20 Cal.3d at p. 432, 143 Cal.Rptr. 225, 573 P.2d 443) (emphasis added).

The competing factors to be weighed under a risk-utility balancing test invite the trier of fact to consider the alternatives and risks faced by the manufacturer and to determine whether in light of these the manufacturer exercised reasonable care in making the design choices it made. In instructing a jury that weighing factors concerning conduct and judgment must yield a conclusion that does not describe conduct is confusing at best.

[...]

51 In Nicholson v. John Deere Ltd. (1986), 58 O.R. (2d) 53, 58 O.R. (2d) 53, 34 D.L.R. (4th) 542 (H.C.), aff'd (1989), 68 O.R. (2d) 191, 57 D.L.R. (4th) 639 (C.A.), Smith J. stated at 60 [O.R.]:

A manufacturer does not have the right to manufacture an inherently dangerous article when a method exists of manufacturing the same article without risk of harm. No amount of or degree of specificity of warning will exonerate him from liability if he does.

52 In Larsen v. General Motors Corp., 391 F. 2d 495 (1968), Gibson J. stated at 503:

We perceive of no sound reason, either in logic or experience, nor any command in precedent, why the manufacturer should not be held to a reasonable duty of care in the design of its vehicle consonant with the state of the art to minimize the effect of accidents. The manufacturers are not insurers but should be held to a standard of reasonable care and design to provide a reasonably safe vehicle in which to travel. Ford Motor Co. v. Zahn, supra. Our streets and highways are increasingly hazardous for the intended normal use of travel and transportation. While advances in highway engineering and non-access, dual highways have considerably increased the safety factor on a miles travelled ratio to accidents, the constant increasing number of vehicles gives impetus to the need of designing and constructing a vehicle that is reasonably safe for the purpose of such travel. At least, the unreasonable risk should be eliminated and reasonable steps in design taken to minimize the injury producing effects of impacts.

This duty of reasonable care in design rests on common law negligence that a manufacturer of an article should use reasonable care in the design and manufacturer of his product to eliminate any unreasonable risk of foreseeable injury. The duty of reasonable care in design should be viewed in light of the risk. While all risks cannot be eliminated nor can a crash-proof vehicle be designed under the present state of the art, there are many common sense factors in design, which are or should be well known to the manufacturer that will minimize or lessen the injurious affects of a collision. The standard of reasonable care is applied in many negligence situations and should be applied here.

53 In the same case, Gibson J. made it clear that the environment in which a product is used must be taken into consideration by the manufacturer and not just the intended use, stating at 502:

While automobiles are not made for the purpose of colliding with each other, a frequent and inevitable contingency of normal automobile use will result in collisions and injury producing impacts.

[...]

55 In Voss v. Black & Decker Manufacturing Co., 450 N.E. 2d 204 (1983), Jasen J. stated at 208:

Much has been written as to what must be shown to establish that the product was defective, including discussions as to the proper distinctions between reasonably safe, not reasonably safe and unreasonably dangerous (Epstein, Modern Product Liability Law, at p.76-92; Swartz, The Concepts of Defective Condition and Unreasonably Dangerous in Products Liability Law, 66 Marquette Law Review 280; Keeton, Product Liability and the Meaning of Defect, 5 St. Mary's Law Journal 30, 35-39; Note 42, Ford Law Review 943). As a result, courts have interchangeably used these terms in instructing jurors concerning the applicable standard for determining whether a product was defectively designed. We believe that a variety of terms with various subtle distinctions in their definitions may tend only to create confusion in ascertaining the proper standard to determine whether or not a given product is defectively designed. Therefore we conclude that the proper standard to be applied should be whether the product as designed was not reasonably safe — that is, whether it is a product which, if the design defect were known at the time of manufacture, a reasonable person would conclude that the utility of the product did not outweigh the risk inherent in marketing a product design in that manner (see 1 NY PJ 12d 138-139 [1982 Supp.]) ...

The plaintiff, of course is under an obligation to present evidence that the product, as designed, was not reasonably safe because there was a substantial likelihood of harm and it was feasible to design the product in a safer manner. The defendant manufacturer, on the other hand, may present evidence in opposition seeking to show that the product is a safe product — that is, one whose utility outweighs its risk when the product has been designed so that the risks are reduced to the greatest extent possible while retaining the product's inherent usefulness at an acceptable cost. ...

In balancing the risks inherent in the product, as designed, against its utility and cost, the jury may consider several factors. (Epstein, Modern Products Liability Law, op. cit.; Kimble and Lesher, Products Liability 55 p.81). Those factors may include the following: (1) utility of the product to the public as a whole and to the individual user; (2) the nature of the product — that is, the likelihood that it will cause injury; (3) the availability of a safer design; (4) the potential for designing and manufacturing the product so that it is safer but remains functional and reasonably priced; (5) the ability of the plaintiff to have avoided injury by careful use of the product; (6) the degree of awareness of the potential danger of the product which reasonably can be attributed to the plaintiff; and (7) the manufacturer's ability to spread any costs related to improving the safety of the design.

[...]

58 In Montreal Transportation Co. v. R., [1923] Ex. C.R. 139, aff'd [1924] 4 D.L.R. 808, which was affirmed [1926] 2 D.L.R. 862 (P.C.), Audette J. stated at 142 [Ex. C.R.]:

... The onus was not discharged by the evidence adduced, limited as it was to inferences and conjectures. The evidence did not negative the possibility of the accident being occasioned by other causes which might just as reasonably, if not more so, be accepted as plausible, than that adopted and relied upon by the suppliants, that is to say, an overfeed from the conveyor to the lofter, notwithstanding the capacity of the conveyor was less than that of the lofter, a cause which, under the evidence, I discard.

When a plaintiff is forced to prove his case from presumptive or circumstantial evidence, such evidence in order to prevail should not only give rise to a presumption in favour of the plaintiff's contention, but should also exclude the possibility of the accident having been occasioned by any other causes than those relied upon by the plaintiff.

59 In Can. Paint Co. v. Trainor (1898), 28 S.C.R. 352, Quinn J. stated at 360:

... Upon the whole of this evidence, we are of the opinion that it does not warrant a judgment which pronounces the accident to have been caused by the fault and neglect of the defendants. The utmost that the evidence warrants is that the cause of the accident still is, as it was at the close of the plaintiff's case, a matter merely speculative and conjectural, and that there appears more probability in the theory suggested by the defendants than in that propounded on behalf of the plaintiff.

In Price v. Smith & Wesson Corp., 2021 ONSC 1114 (CanLII), the Superior Court recently summarized the law regarding negligent design in the context of product liability:

[89] The analysis may begin by placing the negligence in design cause of action in the context of products liability claims generally, for which there are four established genres. First, manufacturers have a duty of care to consumers to see that there are no defects in manufacture that are likely to give rise to injury in the ordinary course of use.55 Second, manufacturers have a duty of care to warn consumers of dangers inherent in the use of the product of which the manufacturer has knowledge or ought to have knowledge.56 Third, manufacturers have a duty of care in designing the product to avoid safety risks and to make the product reasonably safe for its intended purposes.57 Fourth, there is a pure economic loss claim in negligence because manufacturers have a duty of care to compensate consumers for the cost of repairing a dangerous product that presents a real and substantial danger to the public.58

[...]

[91] The underlying argument in a design negligence action is that a manufacturer has a duty of care not to design a product negligently because the manufacturer should and can fairly be held responsible for the choices it makes that affect the safety of the product. The manufacturer has a duty to make reasonable [page709] efforts to reduce any risk to life and limb that may be inherent in its design.59

[92] To succeed in a cause of action for negligent design of a product, the plaintiff must identify the design defect in the product and establish that the defect created a substantial likelihood of harm and that there is, safer and more economically feasible ways to manufacture the product.60

[93] In the case of negligence in designing a product, the defendant is blameworthy for not designing its product in a safer manner. In Nicholson v. John Deere Ltd.,61 Smith J. noted that a manufacturer does not have the right to manufacture an inherently dangerous article when a method exists of manufacturing the same article without risk of harm.

[94] The law does not require a manufacturer to produce articles that are accident proof or incapable of doing harm, but a manufacturer does have a duty to design a product that is not defective. Depending on the product, defectiveness may be determined in relation to the design of the product based on a risk-utility analysis of an alternative safer design of the product.62 In this category of products liability duty of care, whether a manufacturer breaches its duty is determined by a risk-utility analysis that measures whether the utility of the chosen design outweighs the foreseeable risks associated with the chosen design.63

[95] In negligent design cases, the determination of whether a manufacturer breaches its duty of care in designing a product depends upon a risk-utility analysis that measures whether the [page710] utility of the chosen design outweighs the foreseeable risks associated with the chosen design.64 This risk-utility analysis requires weighing any foreseeable risk against the foreseeable utility of the product based on the information available to the manufacturer at the time of distribution or implantation and without the benefit of hindsight.65 Manufacturers are required to weigh the likelihood of both the benefit and the risk offered by a product as well as the value of the potential benefit and the seriousness of the potential risks.66

[96] In Rentway v. Laidlaw,67 Granger J. compiled a list of factors to consider when balancing the risks inherent in the product, as designed, against its utility and cost, namely, (1) the utility of the product to the public as a whole and to the individual user; (2) the nature of the product -- that is, the likelihood that it will cause injury; (3) the availability of a safer design; (4) the potential for designing and manufacturing the product so that it is safer but remains functional and reasonably priced; (5) the ability of the plaintiff to have avoided injury by careful use of the product; (6) the degree of awareness of the potential danger of the product which reasonably can be attributed to the plaintiff; and (7) the manufacturer's ability to spread around any costs related to improving the safety of the design.

In Phillips et al. v. Ford Motor Co. of Canada Ltd. et al., 1971 CanLII 389 (ON CA), the Court of Appeal granted the Defendant's appeal from a judgment of Haines J. (at Phillips et al. v. Ford Motor Co. of Canada Ltd. et al., 1970 CanLII 452 (ON SC)) in favour of the Plaintiff in an action for damages for personal injuries. The Plaintiff had been involved in a motor vehicle accident which he alleged was due to defective parts. The Court of Appeal found that the maxim res ipsa loquitur was inapplicable as there had been too great a time lapse between the date of delivery and the date of the accident. The Court also examined the standard of care for product liability:

While the scope of M'Alister (or Donoghue) v. Stevenson 1932 CanLII 536 (FOREP), [1932] A.C. 562, has been greatly extended and is no longer limited to articles of food and drink, but has been applied to underwear, tombstones, motor-cars, elevators and hair dye, and more recently to house property and articles installed therein, our Courts do not, in product liability cases, impose upon manufacturers, distributors or repairers, as is done in some of the States of the American union, what is virtually strict liability. The standard of care exacted of them under our law is the duty to use reasonable care in the circumstances and nothing more.

It has been argued that the plaintiff can invoke the maxim res ipsa loquitur against both defendants. Certainly as against the Ford Company there is too great a time lapse between the date of delivery of the vehicle to Elgin Motors and the date of the accident. The car had been driven since June, 1965, a distance in excess of 20,000 miles. Moreover, during the intervening period it was repaired and adjusted by Elgin on many occasions. Counsel for the respondents acknowledged that the action as against Ford could not succeed unless he established that there was a faulty design in the concept and installation of the braking system -- more particularly the fail-safe system, viz., the mechanical brakes upon which the driver must rely if the booster fails to operate. He also argues that it was Ford's duty to warn the plaintiff Phillips of this danger.

It was contended by counsel for the respondents, but I thought not too strenuously, that res ipsa loquitur might be invoked as against both defendants. Res ipsa loquitur, which is often referred to as a rule of law or evidence, is essentially nothing more than an instance of circumstantial evidence. It applies whenever common experience or the evidence in a case indicates that the mere happening of an accident may be considered as evidence that reasonable care has not been used. In United Motors Service, Inc. v. Hutson et al., 1937 CanLII 5 (SCC), [1937] S.C.R. 294, [1937] 1 D.L.R. 737, 4 I.L.R. 91, it is made clear that res ipsa loquitur has no effect on the burden of proof, and that the plaintiff has to establish negligence on a balance of probabilities. It does not cast upon the defendant the burden of disproof of negligence, for this would come dangerously close to a fictional use of the maxim as a foundation for the doctrine of strict liability.

In United Motors Service, Inc. v. Hutson, supra, Duff, C.J.C., after quoting the principle as expounded in Scott v. London & St. Katherine Docks Co. (1895), 3 H. & C. 596 at p. 601, 159 E.R. 665, stated at p. 297:

Broadly speaking, in such cases, where the defendant produces an explanation equally consistent with negligence and with no negligence, the burden of establishing negligence still remains with the plaintiff.

The principle embodied in the maxim res ipsa loquitur applies in an action resulting from the negligence of the defendant where it is shown that the thing which caused the accident was under the management of him or his servants, and that the accident was such as in the ordinary course of things would not have happened if proper care had been exercised by him or his servants. It is used in actions for negligence where no proof of negligence is required beyond the accident itself which is such as to involve a prima facie inference of negligence on the part of the defendant, e.g., in the case of a collision between two trains upon a defendant's railway system. It ought not to be applied to evidence of an unexplained accident, if the evidence is as consistent with the cause of the accident having been the victim's own negligence as with its having been that of the defendant.

It is conceivable that there may be circumstances in which the rule might be invoked against the supplier or repairer of a motor-car, e.g., if a brake failure occurred immediately after the customer took delivery of the repaired vehicle. Here, however, the new booster was installed in the vehicle on September 20, 1967, and the motor-car was driven without any brake failure for more than three months and over a distance ranging between 1,100 and 1,200 miles. It is true that in November, 1967, Elgin gave the car what is known as a "75 point check-up", but this was done gratuitously at the instance of the company's president as a goodwill gesture. That thorough investigation revealed a slight leak in the rear main bearing which was remedied. This could have had no effect on the braking capacity of the car and no malfunction of the braking system was disclosed in the course of the check-up. A leak was also discovered in the rear wheel cylinder which Elgin removed and replaced. The car was again the the Elgin garage on December 12th and 18th, but the plaintiff made no complaint about the brakes on those occasions.

Negligence must be proved by the plaintiff and the method of proof is the same as in any other case of negligence. It was said by Lord Macmillan in M'Alister (or Donoghue) v. Stevenson, 1932 CanLII 536 (FOREP), [1932] A.C. 562, that there was no presumption of negligence and that there was no justification for applying the maxim. Later cases have established that this dictum went too far, and that when the circumstances are such as to call for its application it applies in products cases equally with negligence in other cases.

Authorities:
Vester v Boston Scientific Ltd., 2015 ONSC 7950 (CanLII)
Rentway Canada Ltd./Ltée v. Laidlaw Transport Ltd., 1989 CarswellOnt 23, [1989] O.J. No. 786 (Ont High Ct J)
Price v. Smith & Wesson Corp., 2021 ONSC 1114 (CanLII)
Phillips et al. v. Ford Motor Co. of Canada Ltd. et al., 1970 CanLII 452 (ON SC)
Phillips et al. v. Ford Motor Co. of Canada Ltd. et al., 1971 CanLII 389 (ON CA)
Rentway Canada Ltd./Ltée v. Laidlaw Transport Ltd., 1994 CarswellOnt 2790, [1994] O.J. No. 50 (ONCA)