Master California Supreme Court limits the consumer-expectations test in design-defect crashworthiness cases to non-technical failures within common experience, requiring risk–benefit proof for complex vehicle design claims. with this comprehensive case brief.
Soule v. General Motors is a cornerstone California products-liability decision that recalibrates the relationship between two Barker v. Lull avenues for proving design defect—the consumer-expectations test and the risk–benefit test—particularly in crashworthiness (enhanced injury) litigation. In collisions, a manufacturer may be liable if a vehicle’s design does not reasonably protect occupants against foreseeable crash forces, even if the defect did not cause the crash itself. Soule clarifies that not all automobile design claims can be resolved by lay notions of what a car should do in a crash; some claims are too technical and must be evaluated under risk–benefit principles supported by expert evidence.
The court held it was error to instruct a jury on the consumer-expectations test for a complex crashworthiness dispute involving front-suspension and toe-pan intrusion, and that the error was prejudicial. The decision preserves consumer expectations as an alternative theory but confines it to failures whose safety performance ordinary consumers can meaningfully assess from everyday experience. For law students, Soule is the leading case delimiting the scope of California’s design-defect tests and structuring proof, jury instructions, and burdens in crashworthiness cases.
Soule v. General Motors Corp., 8 Cal. 4th 548, 34 Cal. Rptr. 2d 607, 882 P.2d 298 (Cal. 1994)
Plaintiff Soule was driving a Chevrolet Camaro when another driver entered an intersection against a red light, causing a collision. Although General Motors did not cause the accident, Soule alleged the Camaro’s front-end design was defectively crashworthy. In the impact, the left front suspension and wheel assembly allegedly broke loose and intruded rearward into the driver’s footwell; the firewall/toe-pan deformed, collapsing around the footwell and forcing the wheel into Soule’s feet and ankles. Soule suffered severe bilateral lower-extremity injuries. Her experts opined that GM’s design choices—insufficient reinforcement of the front frame members and firewall/toe-pan, inadequate energy management in the front-suspension mountings, and the absence of components to prevent wheel-house intrusion—made the vehicle unreasonably dangerous because foreseeable collision forces could transmit into the occupant compartment. GM countered that the collision dynamics were severe, the design complied with engineering standards, and any intrusion was a function of the crash, not a defect. At trial, the court instructed the jury on both the consumer-expectations and risk–benefit tests. The jury returned a plaintiff’s verdict. On appeal, the propriety and prejudice of the consumer-expectations instruction in this complex crashworthiness case were squarely presented.
In a crashworthiness design-defect case involving complex vehicle systems and technical causation, may the jury be instructed on the consumer-expectations test, or is the plaintiff limited to proving defect under the risk–benefit test supported by expert evidence?
Under Barker v. Lull Engineering Co., a design defect may be proven by either: (1) the consumer-expectations test, which asks whether the product failed to perform as safely as an ordinary consumer would expect when used in an intended or reasonably foreseeable manner; or (2) the risk–benefit test, under which, once the plaintiff proves the design was a substantial factor in causing injury, the burden shifts to the manufacturer to prove that, on balance, the design’s benefits outweigh its inherent risks. Soule limits the consumer-expectations test to cases where the product’s performance in the circumstances is within the common understanding of ordinary consumers; when design choices and their safety implications are technical, complex, and beyond common experience—as is often true in crashworthiness claims—defect must be evaluated under the risk–benefit test with expert evidence. Crashworthiness (enhanced-injury) doctrine permits recovery for design defects that increase or enhance injuries in a foreseeable accident, even if the defect did not cause the accident itself, subject to ordinary causation principles and comparative fault defenses.
The consumer-expectations instruction was improper in this complex crashworthiness design-defect case and its use was prejudicial. The judgment based on that instruction was reversed and the matter remanded for a new trial limited to proper risk–benefit evaluation.
The court emphasized that the consumer-expectations test presupposes that jurors, drawing on everyday experience, can form minimum safety expectations about a product’s performance in the circumstances at issue. That assumption holds for simple mechanisms or obvious malfunctions—e.g., a chair that collapses under normal use or a coffee maker that explodes during ordinary operation. But complex automotive crash performance involves engineering trade-offs, structural load paths, and energy management features outside lay knowledge. Here, the alleged defects concerned the interaction of the front suspension, frame rails, and firewall/toe-pan under collision forces and whether the design should have prevented wheel-house intrusion. Ordinary consumers lack a baseline for how much toe-pan deformation or wheel intrusion is acceptable in a multi-vehicle collision; jurors must instead evaluate risks, feasibility of safer alternatives, cost, utility, and effects on overall vehicle performance—an inquiry suited to the risk–benefit test and expert testimony. By instructing on consumer expectations, the trial court allowed the jury to find defect without engaging the necessary risk–benefit analysis, potentially converting a technical engineering question into a lay referendum on what a car “should” do in a crash. The record showed both parties relied heavily on expert testimony and the defense contested causation and technical feasibility; therefore, the erroneous instruction was not harmless. The court reaffirmed that Barker provides alternative paths to establish defect, but those alternatives are not interchangeable in every case. Consumer expectations remains viable for non-technical failures within common experience (for example, a seatbelt that unbuckles under ordinary load or an airbag that deploys in a non-impact scenario). In contrast, crashworthiness claims that hinge on complex structural design ordinarily require the risk–benefit framework, with the burden-shifting mechanism placing on the manufacturer the proof that the challenged design’s benefits outweighed its risks once plaintiff shows causation.
Soule is the leading California authority confining the consumer-expectations test to truly lay-understandable failures and directing complex crashworthiness design claims to the risk–benefit test. It shapes pleading strategy, expert proof, and especially jury instructions: trial courts must decide as a matter of law whether consumer expectations meaningfully apply to the particular design-performance issue. The case also integrates crashworthiness doctrine within Barker’s framework and reinforces burden shifting under risk–benefit once causation is shown. For law students, Soule illustrates the interaction of doctrine (design defect and enhanced injury), evidence (need for expert testimony), and procedure (instructional error and prejudice) in products liability.
Crashworthiness holds that a manufacturer may be liable for a defect that enhances or aggravates a plaintiff’s injuries in a foreseeable accident, even if the defect did not cause the accident. Soule proceeds on this premise: the plaintiff claimed GM’s front-end design allowed wheel and toe-pan intrusion that worsened injuries. The court did not question crashworthiness; instead, it addressed how to prove a design defect in such cases—concluding that complex crashworthiness claims typically require the risk–benefit test, not consumer expectations.
Only when the product’s safety performance in the circumstances is within ordinary experience. Examples include simple products or obvious malfunctions where jurors can set minimum safety expectations without expert guidance—like a ladder that breaks under normal use or a seat belt that unbuckles during routine loading. In contrast, how a vehicle’s structural systems should deform and manage energy in a collision is typically beyond common experience, so consumer expectations are inapposite.
Under Barker’s risk–benefit test, once the plaintiff proves the design was a substantial factor in causing the injury, the burden shifts to the manufacturer to prove that the design’s benefits outweigh its risks. Relevant factors include the gravity and likelihood of harm, feasibility of safer alternatives, cost, and adverse consequences of proposed alternatives. Soule confirms that this is the proper framework for complex automotive design claims and crashworthiness issues.
No. Soule limits, but does not abolish, the test. The consumer-expectations instruction is proper in auto cases when the failure is within lay understanding—such as a component performing in a plainly aberrant manner. It is improper where the claim turns on technical design trade-offs, such as structural deformation paths, suspension mount design, or airbag algorithmic thresholds requiring expert analysis.
Trial courts must make a threshold determination whether consumer expectations meaningfully apply; if not, the instruction should be refused. Plaintiffs should be prepared to prove causation and present expert testimony under a risk–benefit theory; defendants should marshal risk–benefit evidence to meet their burden once causation is shown. Giving both instructions in a complex case risks reversible error if the jury could rely on consumer expectations to bypass the risk–benefit analysis.
Following Daly v. GM, comparative fault principles may reduce recovery where plaintiff’s negligence contributes to the extent of injury (e.g., seatbelt nonuse), but they do not eliminate the manufacturer’s liability for a design defect that enhances injury. Soule does not alter comparative fault; it clarifies how defect must be proven in technical crashworthiness disputes.
Soule v. GM crystallizes the limits of the consumer-expectations pathway in design-defect litigation and channels complex crashworthiness disputes into the risk–benefit framework. It ensures juries decide highly technical design questions based on expert evidence and a structured balancing of risks and utility, not generalized lay assumptions about what a car should do in a crash.
For practitioners and students, Soule is a roadmap for framing theories of defect, selecting and preparing experts, and crafting accurate jury instructions. It is essential reading for understanding how California courts integrate crashworthiness doctrine with Barker’s dual tests while preserving meaningful, case-specific boundaries on each theory’s use.