## Facts

- Terri F. Soule drove a 1982 Chevrolet Camaro on wet pavement in light rain and was not wearing a seatbelt.
- A 1972 Datsun traveling in the opposite direction skidded into Soule’s vehicle near the left front wheel at an estimated combined closing speed of 30–70 mph.
- Soule alleged a design defect in the Camaro’s crashworthiness: the impact bent the frame and tore loose the wheel-to-frame bracket, causing the left front wheel to collapse rearward and drive the floorboard into her feet.
- Soule suffered severe ankle injuries, including fusion and loss of flexion, with expected deterioration.
- General Motors denied defect and argued the collision forces alone caused the injuries.
- The case featured extensive expert testimony on vehicle design, collision mechanics, and medical causation.
- The jury was instructed on both (1) the ordinary consumer-expectations test and (2) the risk–benefit test for design defect, returned a verdict for Soule, and awarded about $1.65 million.
- GM sought (and was denied) a special causation instruction stating there is no liability if the same injury would have occurred even absent any defect.

## Issues

1. When may a jury apply the ordinary consumer-expectations test to find a product design defective, particularly where safe performance cannot be evaluated through common user experience?
2. In a crashworthiness (enhanced-injury) case, is it error to refuse a defense instruction that no defect is a legal cause if the accident would have produced the same injury without the defect, when general causation instructions were given?
3. If instructional error occurred, is it reversible per se or subject to harmless-error review?

## Decision

- The judgment for Soule was affirmed.
- The trial court erred by instructing on ordinary consumer expectations in a technically complex automotive crashworthiness design case.
- The trial court also should have given GM’s requested special instruction reflecting its theory of enhanced-injury causation.
- Both instructional errors were harmless because the jury received correct risk–benefit and general “substantial factor” causation instructions, the parties tried the case largely through expert evidence, and GM fully argued its causation theory.

## Legal Principles

- A design may be found defective under the ordinary consumer-expectations test only when the product’s everyday use and safety characteristics are within the common experience of ordinary users, such that jurors can evaluate safety without technical analysis.
- When a product’s safe performance in the circumstances cannot be assessed through common experience, design defect should be resolved under the risk–benefit test informed by expert evidence.
- Under the risk–benefit approach, once a plaintiff makes a prima facie showing of design defect, the manufacturer bears the burden to show the design’s benefits outweigh its risks.
- In crashworthiness cases, liability requires that a defect be a substantial factor in causing enhanced injury; a manufacturer is not liable for injuries that would have occurred to the same extent absent the defect.
- Erroneous instructions on the applicable design-defect test or refusal of a correct special causation instruction are not automatically reversible; reversal requires actual prejudice (a reasonable probability of a different result).

## Conclusion

The court affirmed a plaintiff’s crashworthiness verdict while narrowing the consumer-expectations test to situations within ordinary experience, directing complex design-defect claims toward risk–benefit analysis, and holding that related instructional errors warrant reversal only upon a showing of prejudice.


Soule v. Gen. Motors Corp., 8 Cal. 4th 548, 882 P.2d 298 (Cal. 1994)