## Facts

- Cindy Law, driving her parents’ car, allegedly pulled in front of James Harder’s vehicle in Tempe, Arizona, causing Harder to swerve and roll over.
- James Harder and Jean Harder were not wearing seat belts and were ejected from the vehicle during the rollover.
- The Harders suffered severe orthopedic injuries and sued Cindy Law and her parents for negligence.
- During discovery, the Laws sought information about the Harders’ seat-belt use and experience; the Harders objected as irrelevant based on prior Arizona authority rejecting a “seat belt defense.”
- The trial court granted a protective order barring seat-belt discovery, reasoning the plaintiffs had no duty to wear seat belts.

## Issues

1. Under Arizona’s pure comparative fault system, may a defendant introduce evidence that a plaintiff failed to wear an available seat belt to reduce damages by showing the nonuse caused or increased the injuries?
2. If seat-belt nonuse can be relevant to damages under comparative fault, is discovery into plaintiffs’ seat-belt use and experience permissible?

## Decision

- The Arizona Supreme Court approved the Court of Appeals’ approach permitting consideration of seat-belt nonuse under comparative fault when the defendant proves a causal relationship between nonuse and the injuries or their extent.
- The Court rejected framing the rule as imposing an independent tort duty owed to defendants to wear seat belts.
- The Court held the trial court’s protective order was improper because seat-belt-related discovery can be relevant to damages and causation.
- The matter was remanded for further proceedings consistent with allowing discovery and potential admission of seat-belt evidence subject to proof and ordinary evidentiary limits.

## Legal Principles

- In a pure comparative fault regime, a plaintiff’s unreasonable conduct affecting the extent of injury may be considered to proportionally reduce damages.
- Evidence of seat-belt nonuse is admissible on damages only if the defendant presents competent proof that nonuse caused or enhanced the plaintiff’s injuries.
- Seat-belt nonuse is not a complete bar to recovery and is not treated as a categorical breach of a tort duty to the defendant.
- Relevance for discovery follows relevance for admissibility: when seat-belt nonuse may affect damages, discovery into seat-belt availability, knowledge, and usage is permitted.

## Conclusion

Arizona permits a limited seat-belt defense under comparative fault: a defendant may seek reduced damages based on a plaintiff’s failure to use an available seat belt, but only upon a causal showing that nonuse increased the injuries; because the issue can affect damages, related discovery is proper.


Law v. Superior Court, 755 P.2d 1135 (Ariz. 1988)