Barker v. Lull Engineering Co., Inc., 20 Cal. 3d 413, 573 P.2d 443, 143 Cal. Rptr. 225 (Cal. 1978)
Barker v. Lull Engineering is the foundational California Supreme Court decision that defines how plaintiffs can prove a design defect in strict products liability.
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.
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.