PRODUCT LIABILITY | 2026-10-22

Strict Products Liability for Design Defects in California: The Barker Two-Prong Test, the Consumer-Expectation and Risk-Benefit Standards, and When Each Applies

California lets an injured person hold a manufacturer strictly liable for a defectively designed product under either of two tests — the consumer-expectation test or the risk-benefit test — and the Supreme Court’s decisions in Barker and Soule decide which one a jury may use. Knowing how these tests work, and the manufacturer’s burden on risk-benefit, is central to any design-defect case.

When a product injures someone because of the way it was designed — not because of a manufacturing flaw in one unit, but because the entire product line is unreasonably dangerous — California law allows the injured person to hold the manufacturer strictly liable , without proving negligence. Califor

Products-liability law asks a basic question when a product causes injury: was the product defective, and if so, who should bear the loss? California answers that manufacturers who place defective products into the stream of commerce should bear the cost of the injuries those products cause, even without proof of negligence. For design defects — where the claim is that the product was dangerous as designed — California has developed a two-test framework that is both plaintiff-friendly in its burden allocation and carefully bounded in when each test applies. Understanding that framework is essential to evaluating any serious injury caused by a product’s design.

The Foundation: Strict Liability in California

California recognized strict products liability in Greenman v. Yuba Power Products, Inc. (1963) 59 Cal.2d 57, holding that a manufacturer is strictly liable in tort when an article it places on the market, knowing it will be used without inspection for defects, proves to have a defect that causes injury. The policy is that manufacturers are best positioned to anticipate and guard against product hazards and to spread the cost of injuries through pricing and insurance. Strict liability means the plaintiff need not prove the manufacturer was negligent — only that the product was defective and that the defect caused injury while the product was being used in a reasonably foreseeable way. California recognizes three kinds of defect: manufacturing defects, design defects, and warning defects (failure to warn).

Design Defect vs. Manufacturing Defect

The distinction between design and manufacturing defects is fundamental. A manufacturing defect exists when a product departs from its intended design — a single unit came off the line flawed, differing from the others. Manufacturing-defect liability is close to absolute: if the unit differed from the design specification and that difference caused injury, the manufacturer is liable. A design defect, by contrast, means the product was built exactly as intended, but the design itself is unreasonably dangerous — every unit shares the defect. Design-defect cases are harder and more contested because they require evaluating the design choice itself, weighing the product’s dangers against its utility and the feasibility of a safer design. California’s two-test framework is the tool for that evaluation.

Barker and the Two-Prong Test

In Barker v. Lull Engineering Co. (1978) 20 Cal.3d 413, the California Supreme Court held that a product may be found defective in design under either of two alternative tests. First, under the consumer-expectation test, a product is defective in design if it failed to perform as safely as an ordinary consumer would expect when used in an intended or reasonably foreseeable manner. Second, under the risk-benefit test, a product is defective in design if the benefits of the challenged design do not outweigh the risk of danger inherent in the design — and, importantly, once the plaintiff shows the design proximately caused the injury, the burden shifts to the defendant to prove that the benefits outweigh the risks. A plaintiff may prevail under either prong. This dual structure, and especially the burden shift on risk-benefit, is what makes California’s design-defect law distinctive.

The Consumer-Expectation Test

The consumer-expectation test asks whether the product performed as safely as an ordinary consumer would expect. It rests on the idea that products meeting everyday experience carry minimum safety assumptions: a consumer expects a car door to stay shut in an ordinary collision, or a ladder not to collapse under normal weight. Where the test applies, the plaintiff need not present expert testimony on alternative designs or engineering trade-offs; the jury draws on its own experience as product users to decide whether the product met legitimate safety expectations. The test is powerful for plaintiffs in cases where the product’s failure is within common understanding, because it does not require the technical proof the risk-benefit test invites.

The Risk-Benefit Test and the Burden Shift

The risk-benefit test applies where the question of safe design involves technical considerations beyond ordinary experience. Under it, the jury weighs factors such as the gravity and likelihood of the danger, the feasibility and cost of a safer alternative design, and the adverse consequences to the product and consumer of an alternative design. The defining feature is the burden shift: once the plaintiff proves the design proximately caused the injury, the manufacturer must prove that, on balance, the design’s benefits outweigh its risks. This allocation reflects the view that manufacturers have superior access to the technical information about their own design choices. In practice, risk-benefit cases are battles of engineering experts over whether a safer, feasible alternative existed and what it would have cost.

Soule: Which Test Applies

In Soule v. General Motors Corp. (1994) 8 Cal.4th 548, the Supreme Court clarified when each test may be used. The consumer-expectation test is available only where the everyday experience of the product’s users permits a conclusion that the product’s design violated minimum safety assumptions — that is, where the failure is within the common knowledge of ordinary consumers. Where deciding whether the design is defective requires technical, expert evaluation of competing design considerations (as in Soule itself, involving the crashworthiness of a vehicle’s wheel and floorboard design), the consumer-expectation instruction is improper, and the case must go to the jury on the risk-benefit test. Soule thus prevents plaintiffs from using the jury’s lay expectations to decide complex engineering questions, while preserving the consumer-expectation test for product failures ordinary people can evaluate. Choosing the correct test — and getting the right jury instruction (reflected in CACI 1203 and 1204) — is often outcome-determinative.

Failure to Warn as a Separate Theory

Distinct from design defect is the failure-to-warn theory, where the claim is that the product was dangerous without adequate warnings or instructions. In Anderson v. Owens-Corning Fiberglas Corp. (1991) 53 Cal.3d 987, the California Supreme Court held that in a strict-liability failure-to-warn case, a manufacturer is liable for failing to warn of risks that were known or knowable in light of the scientific knowledge available at the time of manufacture — importing a state-of-the-art element into the warning claim. Failure to warn is frequently pleaded alongside design defect, because a product can be both dangerously designed and inadequately labeled. A plaintiff injured by a product should evaluate all three theories — manufacturing defect, design defect, and failure to warn — because they rest on different proof and can apply simultaneously.

Who Can Be Held Liable

Strict products liability in California extends beyond the manufacturer to others in the chain of distribution — including distributors, wholesalers, and retailers — on the theory that all who profit from placing a product in commerce should answer for its defects, with liability generally passing back up the chain by indemnity. This allows an injured plaintiff to recover from a solvent, reachable seller even if the manufacturer is insolvent or beyond the court’s jurisdiction (a common situation with foreign-made goods). Certain parties — such as those who merely provide services or occasional sellers — may fall outside strict liability, and component-part makers have their own rules. Identifying every potentially liable entity in the distribution chain is an important early step, because it affects both the viability and the value of the claim.

Comparative Fault and Common Defenses

Strict liability is not absolute liability, and manufacturers raise several defenses. California applies comparative fault to strict products-liability cases, so a plaintiff’s own negligence — misusing the product in an unforeseeable way, ignoring clear warnings, or altering the product — can reduce recovery in proportion to the plaintiff’s share of responsibility. Manufacturers also argue unforeseeable misuse (the product was used in a way no reasonable manufacturer would anticipate, breaking the chain of liability), substantial modification by a third party after sale, and assumption of risk in some circumstances. In design cases they press the risk-benefit factors hard: that no safer alternative design was feasible, that an alternative would have degraded the product’s utility, or that the design reflected a reasonable engineering trade-off. A further wrinkle is the component-parts doctrine, under which a maker of a non-defective component incorporated into a larger product is generally not liable for the finished product’s design. Anticipating these defenses — and marshaling evidence of a feasible safer design — is central to proving a design-defect case under the risk-benefit standard, where the feasibility of an alternative is often the decisive fact.

Damages in a California Products Case

A plaintiff who proves a design defect may recover the full range of California personal-injury damages. Economic damages include past and future medical expenses, lost wages and earning capacity, and the cost of future care — often the largest category in a catastrophic-injury case. Non-economic damages compensate for pain and suffering, disfigurement, physical impairment, and loss of enjoyment of life, and under Proposition 51 (Civil Code § 1431.2) each defendant’s liability for non-economic damages is several, in proportion to fault. Where a manufacturer acted with malice, oppression, or fraud — for example, knowingly selling a product it understood to be dangerous and concealing the hazard — a plaintiff may seek punitive damages under Civil Code § 3294, subject to a clear-and-convincing-evidence standard. In a wrongful-death case, the decedent’s heirs may recover under Code of Civil Procedure § 377.60, and a survival action may capture the decedent’s own pre-death losses. Because the value of a products case depends on documented injuries and the strength of the liability proof, careful development of both the medical record and the engineering evidence is essential.

Practical Steps for Injured Californians

A person seriously injured by a product should move quickly to preserve the product itself and its packaging, instructions, and purchase records — the product is the central piece of evidence, and spoliation can doom a case. Early expert evaluation is often necessary to assess design alternatives and causation, especially for risk-benefit claims. The plaintiff should identify every entity in the distribution chain and determine which defect theories apply. Claims are subject to California’s two-year personal-injury limitations period (Code of Civil Procedure § 335.1), with the discovery rule affecting when it begins. Because design-defect litigation turns on technical proof, the correct test, and precise jury instructions, and because manufacturers defend these cases aggressively, injured people benefit from experienced products-liability counsel who can marshal the engineering evidence and frame the case under the right standard. Early counsel also helps on a point plaintiffs often overlook: the choice between the consumer-expectation and risk-benefit theories is not merely academic but shapes the entire proof plan, the experts retained, and the jury instructions requested, and getting that choice wrong can hand the defense a reversal on appeal even after a favorable verdict. Framing the case correctly from the outset — matching the theory to the nature of the product failure as Soule requires — is as important as the strength of the underlying evidence. A clear-cut failure within ordinary experience may support a consumer-expectation instruction and a simpler trial, while a complex engineering failure calls for a risk-benefit presentation built around a feasible alternative design; recognizing which case you have, early, lets counsel retain the right experts and preserve the correct jury instruction rather than discovering the mismatch at trial, when it is too late to rebuild the case on the proper theory.

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Frequently Asked Questions

What is a design defect in California products liability?

A design defect means the product was built exactly as intended, but the design itself is unreasonably dangerous, so every unit shares the flaw. It differs from a manufacturing defect, where a single unit departs from its intended design. Design-defect claims are evaluated under the Barker two-prong test.

What are the two tests under Barker v. Lull?

Under Barker v. Lull Engineering Co. (1978) 20 Cal.3d 413, a design is defective if it (1) failed to perform as safely as an ordinary consumer would expect (consumer-expectation test), OR (2) its benefits do not outweigh its risks (risk-benefit test). A plaintiff can prevail under either. Under risk-benefit, once the plaintiff proves the design caused the injury, the burden shifts to the manufacturer.

When does the consumer-expectation test apply?

Under Soule v. General Motors Corp. (1994) 8 Cal.4th 548, only where the product’s failure is within the everyday experience of ordinary users, so the jury can judge it from common knowledge. If deciding defectiveness requires technical, expert evaluation of design trade-offs, the case must proceed on the risk-benefit test instead. Call Trembach Law Firm at (213) 645-2246.

Why does the burden shift matter in a risk-benefit case?

Because once the plaintiff shows the design proximately caused the injury, the manufacturer must prove the design’s benefits outweigh its risks — the manufacturer, not the plaintiff, carries the burden on that balancing. This reflects the manufacturer’s superior access to technical information about its own design choices and is a significant advantage for injured plaintiffs.

Do I have to prove the manufacturer was negligent?

No. Strict products liability (from Greenman v. Yuba Power Products (1963) 59 Cal.2d 57) does not require proof of negligence — only that the product was defective and that the defect caused injury during reasonably foreseeable use. That is what makes strict liability distinct from and often stronger than a negligence claim.

How is failure to warn different from design defect?

Failure to warn claims that the product was dangerous without adequate warnings or instructions. Under Anderson v. Owens-Corning (1991) 53 Cal.3d 987, a manufacturer is strictly liable for failing to warn of risks known or knowable given the scientific knowledge at the time of manufacture. It is often pleaded alongside design defect because a product can be both poorly designed and inadequately labeled.

Who can I sue for a defective product?

Generally everyone in the chain of distribution — manufacturer, distributor, wholesaler, and retailer — because all who profit from placing a product in commerce can be held strictly liable, with indemnity passing liability up the chain. This lets you recover from a solvent, reachable seller even if the manufacturer is insolvent or overseas.

How long do I have to file a design-defect claim?

Generally two years from the injury (Code of Civil Procedure § 335.1), though the discovery rule can affect when the period starts. Preserve the product and its records immediately, since the product is the key evidence and spoliation can defeat the claim. Call Trembach Law Firm at (213) 645-2246.

Talk to a California Products-Liability Lawyer About a Design Defect

If a product injured you because of the way it was designed, California’s strict-liability framework — the Barker consumer-expectation and risk-benefit tests, with the burden shifting to the manufacturer on risk-benefit — may let you recover without proving negligence. Trembach Law Firm, led by Anatolii Trembach (LL.M.; admitted in California), investigates design-defect claims, preserves the product evidence, marshals engineering experts, and frames the case under the correct test. Call (213) 645-2246 for a confidential consultation.

Contact Trembach Law Firm at (818) 514-7680 for a confidential consultation.

Trembach Law Firm | 27001 Agoura Road, Suite 350, Calabasas, CA 91301