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TERRI F. SOULE, Plaintiff and Respondent,
v.
GENERAL MOTORS CORPORATION, Defendant and Appellant.
Supreme Court of California.
*555 COUNSEL
Grace, Skocypec, Cosgrove & Schirm, Barry R. Schirm, Jan L. Pocatera, Susan L. Olson, Lisa M. Kralik, McCutchen, Doyle, Brown & Enersen, David M. Heilbron, Leslie G. Landau and Robert A. Brundage for Defendant and Appellant.
Harry M. Grossman as Amicus Curiae on behalf of Defendant and Appellant.
Charlotte E. Costan, Horton, Barbaro & Reilly, Frank P. Barbaro and Douglas A. Scott for Plaintiff and Respondent.
Ian Herzog, Douglas Devries, Leonard Sachs, Bruce Broillet, David Rosen, Thomas Stolpman, Gary Paul, Robert Steinberg, Roland Wrinkle, Harvey R. Levine, Leonard Esquina, Greene, Broillet, Taylor & Wheeler, Christine Spagnoli, Esner, Marylander, Zakheim & Higa, Stuart B. Esner and Grant Marylander as Amici Curiae on behalf of Plaintiff and Respondent.
*556 OPINION
BAXTER, J.
Plaintiff's ankles were badly injured when her General Motors (GM) car collided with another vehicle. She sued GM, asserting that defects in her automobile allowed its left front wheel to break free, collapse rearward, and smash the floorboard into her feet. GM denied any defect and claimed that the force of the collision itself was the sole cause of the injuries. Expert witnesses debated the issues at length. Plaintiff prevailed at trial, and the Court of Appeal affirmed the judgment.
We granted review to resolve three questions. First, may a product's design be found defective on grounds that the product's performance fell below the safety expectations of the ordinary consumer (see Barker v. Lull Engineering Co. (1978) 20 Cal.3d 413, 426-432 [143 Cal. Rptr. 225, 573 P.2d 443, 96 A.L.R.3d 1]) if the question of how safely the product should have performed cannot be answered by the common experience of its users? Second, in an action for enhanced collision injuries caused by an uncrashworthy vehicle, where a correct general instruction on legal cause is given, is it error to refuse a defense instruction that any defect cannot be a legal cause of injury if the accident would have produced the same injury even without the defect? Third, if the refusal is error, is it reversible per se? (See, e.g., Self v. General Motors Corp. (1974) 42 Cal. App.3d 1, 10-11 [116 Cal. Rptr. 575].)
We reach the following conclusions: The trial court erred by giving an "ordinary consumer expectations" instruction in this complex case. Moreover, the court should have granted GM's request for a special instruction explaining its correct theory of legal cause. However, neither error warrants reversal unless it caused actual prejudice, and both errors were harmless on this record. We will therefore affirm the Court of Appeal's judgment.
FACTS
On the early afternoon of January 16, 1984, plaintiff was driving her 1982 Camaro in the southbound center lane of Bolsa Chica Road, an arterial street in Westminster. There was a slight drizzle, the roadway was damp, and apparently plaintiff was not wearing her seat belt. A 1972 Datsun, approaching northbound, suddenly skidded into the path of plaintiff's car. The Datsun's left rear quarter struck plaintiff's Camaro in an area near the left *557 front wheel. Estimates of the vehicles' combined closing speeds on impact vary from 30 to 70 miles per hour.[1]
The collision bent the Camaro's frame adjacent to the wheel and tore loose the bracket that attached the wheel assembly (specifically, the lower control arm) to the frame. As a result, the wheel collapsed rearward and inward. The wheel hit the underside of the "toe pan" the slanted floorboard area beneath the pedals causing the toe pan to crumple, or "deform," upward into the passenger compartment.
Plaintiff received a fractured rib and relatively minor scalp and knee injuries. Her most severe injuries were fractures of both ankles, and the more serious of these was the compound compression fracture of her left ankle. This injury never healed properly. In order to relieve plaintiff's pain, an orthopedic surgeon fused the joint. As a permanent result, plaintiff cannot flex her left ankle. She walks with considerable difficulty, and her condition is expected to deteriorate.
After the accident, the Camaro was acquired by a salvage dealer, Noah Hipolito. Soon thereafter, plaintiff's son, Jeffrey Bishop, and her original attorney, Richard Hawkins, each inspected and photographed the car and its damaged floorboard area. The failed bracket assembly was retrieved. However, Hipolito later discarded the damaged toe pan, repaired the Camaro, and resold it. Thus, except for the bracket assembly, no part of the vehicle was retained as evidence.
Plaintiff sued GM for her ankle injuries, asserting a theory of strict tort liability for a defective product. She claimed the severe trauma to her ankles was not a natural consequence of the accident, but occurred when the collapse of the Camaro's wheel caused the toe pan to crush violently upward against her feet. Plaintiff attributed the wheel collapse to a manufacturing defect, the substandard quality of the weld attaching the lower control arm bracket to the frame. She also claimed that the placement of the bracket, and the configuration of the frame, were defective designs because they did not limit the wheel's rearward travel in the event the bracket should fail.
The available physical and circumstantial evidence left room for debate about the exact angle and force of the impact and the extent to which the toe pan had actually deformed. The issues of defect and causation were addressed through numerous experts produced by both sides in such areas as *558 biomechanics, metallurgy, orthopedics, design engineering, and crash-test simulation.
Plaintiff submitted the results of crash tests, and also asserted the similarity of another real-world collision involving a 1987 Camaro driven by Dana Carr. According to plaintiff's experts, these examples indicated that Camaro accidents of similar direction and force do not generally produce wheel bracket assembly failure, extensive toe pan deformation, or severe ankle injuries such as those plaintiff had experienced. These experts opined that without the deformation of the toe pan in plaintiff's car, her accident could not have produced enough force to fracture her ankles.
A metallurgist testifying on plaintiff's behalf examined the failed bracket from her car. He concluded that its weld was particularly weak because of excess "porosity" caused by improper welding techniques. Plaintiff's experts also emphasized the alternative frame and bracket design used by the Ford Mustang of comparable model years. They asserted that the Mustang's design, unlike the Camaro's, provided protection against unlimited rearward travel of the wheel should a bracket assembly give way.
GM's metallurgist disputed the claims of excessive weakness or porosity in the bracket weld. Expert witnesses for GM also countered the assertions of defective design. GM asserted that the Camaro's bracket was overdesigned to withstand forces in excess of all expected uses. According to expert testimony adduced by GM, the Mustang's alternative frame and bracket configuration did not fit the Camaro's overall design goals and was not distinctly safer for all collision stresses to which the vehicle might be subjected. Indeed, one witness noted, at least one more recent Ford product had adopted the Camaro's design.
A second major thrust of GM's defense was that the force of the collision, rather than any product defect, was the sole cause of plaintiff's ankle injuries. Using the results of accident reconstruction, computer simulations, and actual crash tests, GM sought to prove that the probable collision force concentrated on the left front wheel of plaintiff's Camaro exceeded the "yield strength" of any feasible weld or design.
By similar means, GM also sought to show that plaintiff's ankle injuries were not caused by the upward movement of the toe pan, but by the inertial forward and downward motion of plaintiff's unrestrained body and legs against the toe pan at the instant of impact. From plaintiff's other injuries, and from photographs showing the general pattern of damage to the Camaro's interior, GM's experts inferred that plaintiff was not wearing her seat belt and had locked or braced her legs in reaction to the imminent collision.
*559 Hence, they concluded, her rigid ankles had absorbed the full force of her inertial forward movement, which was sufficient to cause the fractures. Based on their test results, GM's witnesses opined that plaintiff's ankles had probably moved forward, struck the toe pan, and broken before significant deformation of the toe pan occurred.
The court instructed the jury that a manufacturer is liable for "enhanced" injuries caused by a manufacturing or design defect in its product while the product is being used in a foreseeable way. Over GM's objection, the court gave the standard design defect instruction without modification. (See BAJI No. 9.00.5 (7th ed. 1986).) This instruction advised that a product is defective in design "if it fails to perform as safely as an ordinary consumer would expect when used in an intended or reasonably foreseeable manner or if there is a risk of danger inherent in the design which outweighs the benefit of the design." (Italics added.)
The jury was also told that in order to establish liability for a design defect under the "ordinary consumer expectations" standard, plaintiff must show (1) the manufacturer's product failed to perform as safely as an ordinary consumer would expect, (2) the defect existed when the product left the manufacturer's possession, (3) the defect was a "legal cause" of plaintiff's "enhanced injury," and (4) the product was used in a reasonably foreseeable manner.
With respect to all theories of liability, the instructions indicated that "[a] legal cause of injury is a cause which is a substantial factor in bringing about the injury." (See BAJI No. 3.76 (7th ed. 1986).) However, the trial court refused the following instruction proffered by GM: "If you find that the subject Camaro ... was improperly designed, but you also find that [plaintiff] would have received enhanced injuries even if the design had been proper, then you must find that the design was not a substantial factor in bringing about her injuries and therefore was not a contributing cause thereto."
In a series of special findings, the jury determined that the Camaro contained a defect (of unspecified nature) which was a "legal cause" of plaintiff's "enhanced injury." The jury further concluded that although plaintiff was guilty of comparative fault, her conduct was not a legal cause of her enhanced injuries. Plaintiff received an award of $1.65 million.
GM appealed. Among other things, it argued that the trial court erred by instructing on ordinary consumer expectations in a complex design-defect case, and by failing to give GM's special instruction on causation.
*560 Following one line of authority, the Court of Appeal concluded that a jury may rely on expert assistance to determine what level of safe performance an ordinary consumer would expect under particular circumstances. Hence, the Court of Appeal ruled, there was no error in use of the ordinary consumer expectations standard for design defect in this case.
The Court of Appeal agreed with GM that its specific instruction on causation should not have been refused. However, the court rejected precedent suggesting that an error of this kind is reversible per se. Here, the Court of Appeal ruled, the error was harmless. After dismissing GM's remaining appellate claims, the Court of Appeal affirmed the judgment. We granted review.
DISCUSSION
1. Test for design defect.
(1) A manufacturer, distributor, or retailer is liable in tort if a defect in the manufacture or design of its product causes injury while the product is being used in a reasonably foreseeable way. (Cronin v. J.B.E. Olson Corp. (1972) 8 Cal.3d 121, 126-130 [104 Cal. Rptr. 433, 501 P.2d 1153] (Cronin); Greenman v. Yuba Power Products, Inc. (1963) 59 Cal.2d 57, 62 [27 Cal. Rptr. 697, 377 P.2d 897, 13 A.L.R.3d 1049] (Greenman).) Because traffic accidents are foreseeable, vehicle manufacturers must consider collision safety when they design and build their products. Thus, whatever the cause of an accident, a vehicle's producer is liable for specific collision injuries that would not have occurred but for a manufacturing or design defect in the vehicle. (Cronin, supra, at p. 126.)
In Cronin, supra, a bread van driver was hurt when the hasp retaining the bread trays broke during a collision, causing the trays to shift forward and propel him through the windshield. He sued the van's producer, alleging that the hasp had failed because of the defective metal used in its manufacture. The court instructed that the driver could recover if he proved a defect, unknown to him, which caused injury while the van was being used as intended or designed. The manufacturer appealed the subsequent damage award. It urged the court should have instructed that liability could not be imposed unless the defect rendered the product "unreasonably dangerous."
We rejected this contention, holding that the "unreasonably dangerous" test derived from the Restatement (see Rest.2d Torts, § 402A) is inapplicable in California. As we observed, the Restatement defines "unreasonably dangerous" as "dangerous to an extent beyond that which would be contemplated by the ordinary consumer who purchases it, with the ordinary knowledge common to the community as to its characteristics." (Id., com. i, p. 352, *561 italics added.) The original purpose of this formula, we explained, was to make clear that common products such as sugar, butter, and liquor are not defective simply because they pose inherent health risks well known to the general public. However, Cronin indicated, the formula had been applied so as to force injured persons to prove both an actual defect and "unreasonable" danger. (8 Cal.3d at pp. 132-133.)
This "double burden," Cronin reasoned, ran contrary to the purpose of Greenman, supra, to relieve persons injured by defective products from proof of elements that ring of negligence. Instead, Cronin concluded, an injured plaintiff should recover so long as he proves that the product was defective, and that the defect caused injury in reasonably foreseeable use. (Cronin, supra, 8 Cal.3d at pp. 133-134.)
In Barker v. Lull Engineering Co., supra, 20 Cal.3d 413 (Barker), the operator of a high-lift loader sued its manufacturer for injuries he received when the loader toppled during a lift on sloping ground. The operator alleged various design defects which made the loader unsafe to use on a slope. In a pre-Cronin trial, the court instructed that the operator could recover only if a defect in the loader's design made the machine "`unreasonably dangerous for its intended use.'" (Id., at p. 417.) The operator appealed the defense verdict, citing the "unreasonably dangerous" instruction as prejudicial error.
The manufacturer responded that even if the "unreasonably dangerous" test was inappropriate for manufacturing defects, such as the substandard fastener material in Cronin, it should be retained for design defects. This rule would not produce the undue double burden that concerned us in Cronin, the manufacturer insisted, because unreasonable danger is part of the definition of design defect, not an additional element of strict product liability. Without this limitation, the manufacturer contended, juries would lack guidance when determining if a defect had sprung not from a mistake in supply or assembly, but from a flaw in the product's specifications.
The Barker court disagreed. It reasoned as follows: Our concerns in Cronin extended beyond double-burden problems. There we also sought to avoid the danger that a jury would deny recovery, as the Restatement had intended, "so long as the product did not fall below the ordinary consumer's expectations as to [its] safety...." (Barker, supra, 20 Cal.3d at p. 425, fn. omitted.) This danger was particularly acute in design defect cases, where a manufacturer might argue that because the item which caused injury was identical to others of the same product line, it must necessarily have satisfied ordinary consumer expectations. (Id., at p. 426.)
*562 Despite these difficulties, Barker explained, it is possible to define a design defect, and the expectations of the ordinary consumer are relevant to that issue. (2) At a minimum, said Barker, a product is defective in design if it does fail to perform as safely as an ordinary consumer would expect. This principle, Barker asserted, acknowledges the relationship between strict tort liability for a defective product and the common law doctrine of warranty, which holds that a product's presence on the market includes an implied representation "`that it [will] safely do the jobs for which it was built.'" (20 Cal.3d at p. 430, quoting Greenman, supra, 59 Cal.2d at p. 64.) "Under this [minimum] standard," Barker observed, "an injured plaintiff will frequently be able to demonstrate the defectiveness of the product by resort to circumstantial evidence, even when the accident itself precludes identification of the specific defect at fault. [Citations.]" (20 Cal.3d at p. 430, italics added.)
However, Barker asserted, the Restatement had erred in proposing that a violation of ordinary consumer expectations was necessary for recovery on this ground. "As Professor Wade has pointed out, ... the expectations of the ordinary consumer cannot be viewed as the exclusive yardstick for evaluating design defectiveness because `[i]n many situations ... the consumer would not know what to expect, because he would have no idea how safe the product could be made.'" (20 Cal.3d at p. 430, quoting Wade, On the Nature of Strict Tort Liability for Products (1973) 44 Miss. L.J. 825, 829, italics added.)
Thus, Barker concluded, "a product may be found defective in design, even if it satisfies ordinary consumer expectations, if through hindsight the jury determines that the product's design embodies `excessive preventable danger,' or, in other words, if the jury finds that the risk of danger inherent in the challenged design outweighs the benefits of such design. [Citations.]" (20 Cal.3d at p. 430, fn. omitted.) Barker held that under this latter standard, "a jury may consider, among other relevant factors, the gravity of the danger posed by the challenged design, the likelihood that such danger would occur, the mechanical feasibility of a safer alternative design, the financial cost of an improved design, and the adverse consequences to the product and to the consumer that would result from an alternative design. [Citations.]" (Id., at p. 431.)
Barker also made clear that when the ultimate issue of design defect calls for a careful assessment of feasibility, practicality, risk, and benefit, the case should not be resolved simply on the basis of ordinary consumer expectations. As Barker observed, "past design defect decisions demonstrate that, as a practical matter, in many instances it is simply impossible to eliminate the *563 balancing or weighing of competing considerations in determining whether a product is defectively designed or not...." (20 Cal.3d at p. 433.)
An example, Barker noted, was the "crashworthiness" issue presented in Self v. General Motors Corp., supra, 42 Cal. App.3d 1. The debate there was whether the explosion of a vehicle's fuel tank in an accident was due to a defect in design. This, in turn, entailed concerns about whether placement of the tank in a position less vulnerable to rear end collisions, even if technically feasible, "would have created a greater risk of injury in other, more common situations." (Barker, supra, 20 Cal.3d at p. 433.) Because this complex weighing of risks, benefits, and practical alternatives is "implicit" in so many design-defect determinations, Barker concluded, "an instruction which appears to preclude such a weighing process under all circumstances may mislead the jury." (Id., at p. 434.)
Campbell v. General Motors Corp. (1982) 32 Cal.3d 112 [184 Cal. Rptr. 891, 649 P.2d 224] (Campbell) provided additional strong hints about the proper use of the ordinary consumer expectations prong of Barker. Plaintiff Campbell, a bus passenger, was thrown from her seat and injured during a sharp turn. She sued GM, the manufacturer of the bus, alleging that the vehicle was defectively designed because there was no "grab bar" within easy reach of her seat. Campbell presented no expert testimony, but she submitted photographs of the interior of the bus, showing where safety bars and handles were located in relation to the seat she had occupied. At the conclusion of her case in chief, GM moved for nonsuit, arguing that her evidence of design defect and proximate cause was not sufficient. The trial court granted the motion, but we reversed.
We emphasized that in order to establish a design defect under Barker's ordinary consumer expectations test, it was enough for Campbell to show "the objective conditions of the product" so that the jurors could employ "[their] own sense of whether the product meets ordinary expectations as to its safety under the circumstances presented by the evidence. [Fn. omitted.] Since public transportation is a matter of common experience, no expert testimony was required to enable the jury to reach a decision on this part of the Barker inquiry." (Campbell, supra, 32 Cal.3d at p. 126.)
"Indeed, it is difficult to conceive what testimony an `expert' could provide. The thrust of the first Barker test is that the product must meet the safety expectations of the general public as represented by the ordinary consumer, not the industry or a government agency. `[O]ne can hardly imagine what credentials a witness must possess before he can be certified as an expert on the issue of ordinary consumer expectations.'" (Campbell, *564 supra, 32 Cal.3d at pp. 126-127, quoting Schwartz, Foreword: Understanding Products Liability (1979) 67 Cal.L.Rev. 435, 480, italics added.)
Had we ended our discussion at this point, it would have been clear that a product violates ordinary consumer expectations only when the circumstances arouse such reasonable expectations based on common experience of the product's users. However, dictum in the next paragraph of Campbell injected ambiguity. We said, "The quantum of proof necessary to establish a prima facie case ... under the first [i.e., ordinary consumer expectations] prong of Barker cannot be reduced to an easy formula. However, if the product is one within the common experience of ordinary consumers" (italics added), it will generally be enough for the injured plaintiff to show the circumstances of the accident and "the objective features of the product which are relevant to an evaluation of its safety...." (32 Cal.3d at p. 127.) One might infer from this passage that the ordinary consumer expectations prong of Barker is not limited to product performance "within the common experience" of the product's ordinary consumers.
Several subsequent Court of Appeal cases considered the point. In Bates v. John Deere Co. (1983) 148 Cal. App.3d 40 [195 Cal. Rptr. 637], plaintiff caught his leg in a commercial cotton picker while clearing debris from the moving machinery. He claimed the machine should have included an emergency shutoff switch within reach of the remote position from which its sole operator periodically had to undertake this debris-clearing task. Defense experts suggested that such a feature might induce a false sense of security and make the machine even more dangerous.
The trial court properly found a design defect under the risk-benefit test, but defendant challenged the court's additional use of the ordinary consumer expectations test. Although it saw no need to decide the issue, the Court of Appeal agreed that "[w]e, too, find it difficult to apply the ... [consumer expectations] test to these facts, in part because it is difficult to conceive that an ordinary consumer would know what to expect concerning the safety design of a commercial cotton picker. [Citing Barker.]" (148 Cal. App.3d at p. 52.)
In Lunghi v. Clark Equipment Co. (1984) 153 Cal. App.3d 485 [200 Cal. Rptr. 387], the Court of Appeal upheld the trial court's refusal to instruct on reasonable consumer expectations because unassisted lay jurors "would not know what to expect" about the safety design of a Bobcat model 440 loader, and no experts had testified on the issue. However, the Court of Appeal remarked that on retrial, "appellants are free to present evidence in the form of expert opinions on the reasonable expectations of consumers of the product involved here...." (Id., at p. 496.)
*565 In Akers v. Kelly Co. (1985) 173 Cal. App.3d 633 [219 Cal. Rptr. 513] (Akers), there was an accident involving a "dockboard," a spring-loaded plate which attaches to a loading dock and adjusts to form a bridge between the dock and truck beds of different elevations. Several hours after the prongs of a forklift struck the dockboard, it suddenly flew apart, injuring a nearby worker. Experts debated at length whether the dockboard's components should have been designed to withstand forklift impacts, and whether a failure in design was a cause of the accident. Over defendant's objection, the trial court instructed only on the consumer expectations test for design defect.
The Court of Appeal affirmed. It declined to read Campbell as limiting the consumer expectations test to products or accidents of common experience. (Akers, supra, 173 Cal. App.3d at p. 650.) That test, said Akers, "is entirely appropriate in a case such as this one. There are certain kinds of accidents even where fairly complex machinery is involved which are so bizarre that the average juror, upon hearing the particulars, might reasonably think: `Whatever the user may have expected from that contraption, it certainly wasn't that.' Here, a dockboard flew apart and injured [plaintiff]. A reasonable juror with no previous experience of dockboards could conclude that the dockboard in question failed to meet `consumer expectations' as to its safety...." (Id., at p. 651.) This was so, the Court of Appeal concluded, even though expert testimony might be necessary to establish that the manufacturer was responsible for the flaw which caused the product to fail. (Ibid.)
To similar effect is West v. Johnson & Johnson Products, Inc. (1985) 174 Cal. App.3d 831 [220 Cal. Rptr. 437, 59 A.L.R.4th 1] (West). The plaintiff in West became seriously ill in February 1980, during her menstrual period. At this time, there were increasing indications that tampon use sometimes causes toxic shock syndrome (TSS). After reading medical reports, plaintiff's physicians belatedly concluded that she had suffered TSS caused by tampons which defendant had designed and produced. At trial, experts debated the nature of plaintiff's illness, and they also disputed whether the tampon design and materials used by defendant encouraged TSS. The trial court instructed only on the consumer expectations prong of Barker.
On appeal, defendant argued that the risk-benefit test alone was proper. However, West agreed with Akers that Campbell does not preclude the consumer expectations test in complex cases involving expert testimony. In a time before general awareness and warnings about TSS, the court reasoned, plaintiff "had every right to expect" that use of this seemingly innocuous product "would not lead to a serious (or perhaps fatal) illness...." Hence, the consumer expectations instruction was appropriate. (West, supra, 174 Cal. App.3d at p. 867.)
*566 Finally, in Rosburg v. Minnesota Mining & Mfg. Co. (1986) 181 Cal. App.3d 726 [226 Cal. Rptr. 299], plaintiff claimed she was entitled to judgment under the consumer expectations test because her own testimony that she believed her breast implants would last a lifetime without leaking was the only lay evidence of what consumers expected. However, the Court of Appeal ruled that breast implant performance is beyond common experience, and that expert testimony on what the consumer should expect was therefore relevant and admissible. Here, the court observed, both plaintiff's surgeon and another defense expert had insisted that failures were expectable and patients were not advised otherwise. Hence, there was substantial evidence to support the finding below that no defect was proven under the consumer expectations test. (Id., at pp. 732-733.)[2]
(3) In Barker, we offered two alternative ways to prove a design defect, each appropriate to its own circumstances. The purposes, behaviors, and dangers of certain products are commonly understood by those who ordinarily use them. By the same token, the ordinary users or consumers of a product may have reasonable, widely accepted minimum expectations about the circumstances under which it should perform safely. Consumers govern their own conduct by these expectations, and products on the market should conform to them.
In some cases, therefore, "ordinary knowledge ... as to ... [the product's] characteristics" (Rest.2d Torts, supra, § 402A, com. i., p. 352) may permit an inference that the product did not perform as safely as it should. If the facts permit such a conclusion, and if the failure resulted from the product's design, a finding of defect is warranted without any further proof. The manufacturer may not defend a claim that a product's design failed to perform as safely as its ordinary consumers would expect by presenting expert evidence of the design's relative risks and benefits.[3]
However, as we noted in Barker, a complex product, even when it is being used as intended, may often cause injury in a way that does not engage its *567 ordinary consumers' reasonable minimum assumptions about safe performance. For example, the ordinary consumer of an automobile simply has "no idea" how it should perform in all foreseeable situations, or how safe it should be made against all foreseeable hazards. (Barker, supra, 20 Cal.3d at p. 430.)
An injured person is not foreclosed from proving a defect in the product's design simply because he cannot show that the reasonable minimum safety expectations of its ordinary consumers were violated. Under Barker's alternative test, a product is still defective if its design embodies "excessive preventable danger" (20 Cal.3d at p. 430), that is, unless "the benefits of the ... design outweigh the risk of danger inherent in such design" (id., at p. 432). But this determination involves technical issues of feasibility, cost, practicality, risk, and benefit (id., at p. 431) which are "impossible" to avoid (id., at p. 433). In such cases, the jury must consider the manufacturer's evidence of competing design considerations (id., at pp. 433-434), and the issue of design defect cannot fairly be resolved by standardless reference to the "expectations" of an "ordinary consumer."
(4) As we have seen, the consumer expectations test is reserved for cases in which the everyday experience of the product's users permits a conclusion that the product's design violated minimum safety assumptions, and is thus defective regardless of expert opinion about the merits of the design. It follows that where the minimum safety of a produc