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What are the design defect tests in California products liability?

California · updated 2026-08-31 · 528 words · 4 authorities cited

In California, design defect claims in products liability are evaluated using two primary tests: the consumer expectation test and the risk-benefit test [5, 6]. A product is deemed defective in design if it fails to perform as safely as an ordinary consumer would expect, or if the risks of the design outweigh its benefits [5, 6].

The rule

A product is defectively designed if it fails to perform as safely as an ordinary consumer would expect when used or misused in an intended or reasonably foreseeable way 5. Alternatively, a product is defectively designed if the benefits of the design do not outweigh the risks of the design 6.

How it applies

To establish a design defect claim under the consumer expectation test, a plaintiff must prove that the defendant manufactured, distributed, or sold the product, that the product did not perform as safely as an ordinary consumer would have expected when used or misused in an intended or reasonably foreseeable way, that the plaintiff was harmed, and that the product's failure to perform safely was a substantial factor in causing the harm 5. This test focuses on the objective expectations of an ordinary consumer regarding the product's safety 5.

Under the risk-benefit test, a plaintiff must prove that the defendant manufactured, distributed, or sold the product, that the plaintiff was harmed, and that the product's design was a substantial factor in causing the harm 6. If the plaintiff proves these elements, the burden shifts to the defendant to prove that the benefits of the product's design outweigh its risks 6. In determining whether the benefits outweigh the risks, factors to consider include the gravity of the potential harm, the likelihood of harm, the feasibility and cost of an alternative safer design at the time of manufacture, and the disadvantages of an alternative design 6. Other relevant factors may also be considered 6.

An affirmative defense to a design defect claim exists if the product was misused or modified after leaving the defendant's possession in a way that was so highly extraordinary that it was not reasonably foreseeable, and this misuse or modification was the sole cause of the plaintiff's harm 1.

What this does not cover

The provided sources do not detail the specific legal standards for determining what constitutes "intended or reasonably foreseeable use or misuse" under the consumer expectation test, nor do they elaborate on the evidentiary requirements for proving the various factors considered in the risk-benefit analysis beyond listing them [5, 6]. The sources also do not cover the interplay between design defect claims and other types of product liability claims, such as manufacturing defects or negligence, except to distinguish them in verdict forms [3, 4]. Furthermore, while an affirmative defense for misuse or modification is mentioned, the sources do not provide a comprehensive list of all potential affirmative defenses in design defect cases 1. The sources also do not address the specific application of these tests to all types of products, though they do mention an exemption for certain inherently unsafe common consumer products like sugar or alcohol, provided they are known to be unsafe by the ordinary consumer 7.

Authorities cited

1. CACI VF-1201

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2. CACI 1203

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3. CACI 1204

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4. CIV 1714.45

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