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When is a manufacturer liable for failure to warn in California?

California · updated 2026-09-01 · 582 words · 5 authorities cited

A manufacturer in California is liable for failure to warn if it knew or should have known its product was dangerous, users would not realize the danger, it failed to adequately warn, a reasonable manufacturer would have warned, and this failure caused harm. This applies under both negligence and strict liability theories.

The rule

A manufacturer is liable for negligent failure to warn if it manufactured, distributed, or sold the product; knew or reasonably should have known the product was dangerous when used or misused foreseeably; knew or reasonably should have known users would not realize the danger; failed to adequately warn or instruct on safe use; a reasonable manufacturer would have warned; and this failure was a substantial factor in causing harm 3. For strict liability, a manufacturer is liable if the product had potential risks known or knowable by scientific and medical knowledge at the time of manufacture, distribution, or sale; these risks presented a substantial danger in foreseeable use; ordinary consumers would not recognize these risks; the manufacturer failed to adequately warn or instruct; and this lack of warning was a substantial factor in causing harm 4.

How it applies

The duty to warn arises when a manufacturer knows or reasonably should know of a product's danger and that users would not recognize that danger 3. This duty extends to dangers associated with both intended and reasonably foreseeable misuse of the product 3. The warning itself must be adequate 3. In cases involving prescription products, the warning must be given to the prescribing physician and include potential risks or side effects that may follow foreseeable use 3. The manufacturer has a continuing duty to warn physicians as long as the product is in use 3.

There are specific exceptions where a manufacturer is not liable. A manufacturer is not liable if the product is inherently unsafe and known to be unsafe by the ordinary consumer with common community knowledge, and the product is a common consumer product intended for personal consumption, such as sugar, castor oil, alcohol, and butter 2. This exemption does not apply to tobacco products manufactured or sold by tobacco manufacturers, but it does exempt the sale or distribution of tobacco products by other persons like retailers or distributors 2. This exemption also does not apply to actions based on a manufacturing defect or breach of an express warranty 2.

Manufacturers making express warranties for consumer goods must set forth those warranties in simple, readily understood language, clearly identifying the warrantor, and conforming to federal standards 5. If a warranty or product registration card is provided, it must inform the consumer that it is for product registration and that failure to return it does not diminish warranty rights 5.

What this does not cover

The provided sources do not detail the specific content or format requirements for an "adequate" warning beyond stating that a warning must be adequate 3. They also do not elaborate on what constitutes "reasonable foreseeability" of use or misuse in various contexts 3. The sources do not cover the nuances of a manufacturer's duty to recall or retrofit products, although they do mention that a manufacturer can be negligent for failing to recall or retrofit a product if it became aware of a defect after sale and a reasonable manufacturer would have done so 6. The sources also do not extensively cover the interplay between express warranties and the duty to warn, beyond general requirements for express warranties 5.

Authorities cited

1. CIV 1714.45

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2. CACI 1222

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3. CACI 1205

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4. CIV 1793.1

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5. CACI 1223

Cited in this article. Open Basil Brief to read the passage in full.

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