Master California Supreme Court establishes the dual tests and burden-shifting framework for strict products liability design defects. with this comprehensive case brief.
Barker v. Lull Engineering is the foundational California Supreme Court decision that defines how plaintiffs can prove a design defect in strict products liability. Rejecting a one-size-fits-all approach, the court articulated two alternative tests—the consumer expectations test and the risk-benefit test—and, crucially, shifted the burden of proof to the manufacturer under the risk-benefit test once the plaintiff shows the design was a substantial factor in causing injury. This structure reflects a pragmatic recognition that some products present hazards and design tradeoffs beyond the ken of ordinary consumers and that manufacturers possess superior access to design information and risk-utility data.
For law students, Barker is essential not only because it supplies the doctrinal backbone for California design-defect claims, but also because it illustrates how courts balance consumer protection with innovation incentives. Barker harmonizes earlier California strict liability cases (such as Cronin) by preserving plaintiff-friendly principles while restoring a reasoned balancing framework without reintroducing the Restatement’s “unreasonably dangerous” language. It remains a touchstone for analyzing design defect claims and understanding later refinements, including Soule’s guidance on when consumer expectations applies and the Restatement (Third)’s alternative-design emphasis that many jurisdictions later adopted.
Barker v. Lull Engineering Co., Inc., 20 Cal. 3d 413, 573 P.2d 443, 143 Cal. Rptr. 225 (Cal. 1978)
The plaintiff, a construction worker, was injured while operating a Lull high-lift loader—a telescoping boom material-handling machine—at a residential construction site. The terrain was uneven and sloped, and the machine was being used to move and place heavy loads at height. The plaintiff had limited experience with the equipment and received minimal instruction. During operation with a heavy load elevated, the machine became unstable and either lurched or tipped, causing the plaintiff to sustain serious injuries. He sued the manufacturer, Lull Engineering, alleging strict products liability for defective design and inadequate warnings, contending that the loader’s design rendered it unreasonably susceptible to instability in foreseeable field conditions and lacked adequate safety features or instructions to guard against that hazard. At trial, the jury was instructed under standards that effectively required the plaintiff to prove the product was “unreasonably dangerous” and did not implement a risk-benefit burden shift. The jury returned a defense verdict, and the plaintiff appealed, challenging the design-defect standard and allocation of burdens.
What is the proper legal standard and burden of proof for establishing a design defect in a strict products liability action under California law?
A product is defective in design under California strict products liability if, at the time of sale or distribution, either of two alternative tests is satisfied: 1) Consumer expectations test: The product failed to perform as safely as an ordinary consumer would expect when used in an intended or reasonably foreseeable manner. 2) Risk-benefit test: If the plaintiff proves that the product’s design was a substantial factor in causing injury, the burden shifts to the defendant to prove that, on balance, the benefits of the challenged design outweigh the inherent risks. Relevant factors include the gravity of the danger, the likelihood of injury, the mechanical feasibility of a safer alternative design, the financial cost of an improved design, and any adverse consequences to the product’s utility and to consumers resulting from an alternative design. The plaintiff need not prove a specific feasible alternative design to establish defect, though such evidence is relevant to the risk-benefit analysis. The design-defect inquiry does not require proof that the product was “unreasonably dangerous” as phrased in Restatement (Second) of Torts § 402A.
The California Supreme Court adopted a dual-test framework for design defects, recognized a burden shift to the manufacturer under the risk-benefit test once causation is shown, and rejected jury instructions requiring plaintiffs to prove the product was “unreasonably dangerous.” The defense verdict was reversed and the case remanded for a new trial under the proper standards.
The court reasoned that design-defect doctrine must protect consumers without stifling useful product designs. Consumer expectations can be a sufficient measure of defect where lay users can form reasonable safety expectations about a product’s performance. But for complex products or hazards not within common experience, ordinary expectations may be indeterminate, making a pure consumer-expectations test inadequate. In such cases, a risk-benefit analysis better captures whether the design should be deemed defective. Importantly, the court placed the burden on manufacturers to justify the challenged design once the plaintiff establishes a causal link between the design and the injury. Manufacturers are best positioned to access and present evidence about design choices, safety tradeoffs, feasibility, and cost because they control design decisions and possess technical information. Shifting the burden in the risk-benefit framework ensures an equitable distribution of proof and avoids effectively collapsing strict liability into negligence by demanding plaintiffs prove design fault solely through complex engineering evidence. The court further clarified that after Cronin, California law does not require the plaintiff to show the product was “unreasonably dangerous” as a separate element. While concepts of reasonableness and danger inevitably inform the risk-benefit test, the doctrinal label from § 402A is unnecessary and potentially misleading. Finally, the court reaffirmed that intended or reasonably foreseeable use frames the defect inquiry, and evidence of safer alternative designs, compliance with regulations, and industry custom may be considered but is not dispositive.
Barker anchors California’s strict products liability design-defect doctrine by establishing two alternative routes to prove defect and by shifting the burden of persuasion to the manufacturer under the risk-benefit test once causation is shown. It clarifies that plaintiffs need not produce a specific alternative design, though such evidence is relevant, and it rejects the “unreasonably dangerous” formulation from § 402A. Barker’s framework remains central to exam analysis and practice: it determines how to select between consumer expectations and risk-benefit, what each party must prove, and how to present engineering, feasibility, and cost evidence. Later California cases—especially Soule v. GM—refined when consumer expectations applies, but Barker’s dual-test, burden-shifting structure is still the baseline in California products liability jurisprudence.
Barker recognizes two alternative tests: (1) the consumer expectations test—whether the product failed to perform as safely as an ordinary consumer would expect in intended or reasonably foreseeable use; and (2) the risk-benefit test—if the plaintiff shows the design was a substantial factor in causing injury, the manufacturer must prove the benefits of the design outweigh its risks considering gravity and likelihood of harm, feasibility of safer designs, costs, and adverse consequences to utility.
Under the risk-benefit test. Once the plaintiff proves that the challenged design was a substantial factor in causing the injury, the burden shifts to the manufacturer to establish that, in light of relevant factors, the design’s benefits outweigh its risks.
No. Barker expressly states that a plaintiff need not prove a specific feasible alternative design to establish a design defect. However, evidence of feasible alternatives is relevant and often persuasive in the risk-benefit analysis.
Consumer expectations is appropriate where ordinary consumers can form reasonable safety expectations about the product’s performance (e.g., simple products or well-understood hazards). For complex products or technical design tradeoffs beyond common knowledge, courts typically rely on the risk-benefit test, often requiring expert testimony and applying the Barker burden shift to the manufacturer.
Cronin eliminated the Restatement’s “unreasonably dangerous” requirement in California strict liability. Barker built on Cronin by articulating the dual tests and burden shifting for design defects. Soule later limited the use of consumer expectations to cases where lay experience provides a reasonable basis for safety expectations, steering complex design cases toward risk-benefit analysis.
Comparative fault generally applies to strict products liability in California (as recognized in Daly v. GM). While Barker itself focuses on defining design-defect tests and burden allocation, in practice a plaintiff’s negligent conduct, misuse, or assumption of risk may reduce recovery or defeat causation if the use was not intended or reasonably foreseeable.
Barker v. Lull Engineering is the cornerstone of California’s design-defect law. It gives plaintiffs two doctrinal pathways—consumer expectations and risk-benefit—and rebalances proof by shifting the burden to manufacturers to justify contested design choices once causation is shown. The decision aligns strict liability’s consumer-protection goals with a realistic evidentiary framework reflective of the manufacturer’s superior access to design information.
For law students and practitioners, Barker’s enduring value lies in its analytical roadmap: identify the appropriate test, allocate burdens correctly, marshal expert and feasibility evidence where needed, and evaluate foreseeable uses. Mastery of Barker positions you to analyze and litigate design-defect claims effectively in California and to contrast California’s approach with jurisdictions that require proof of a reasonable alternative design under the Restatement (Third).