## Facts

- Magdalene Smoot alleged she was injured when the airbags in her Mazda deployed after she hit a pothole or chunk of asphalt while driving about 35–40 miles per hour.
- The day before the incident, she received a recall notice warning that airbags in certain vehicles could deploy at low speeds; she scheduled service, but the incident occurred before the appointment.
- After the incident, the vehicle was repaired and sold, and thus was unavailable for inspection in the litigation.
- Magdalene Smoot and Ryan Smoot sued Mazda Motors of America, Inc. and Tokio Marine and Fire Insurance Company, Ltd. in a diversity action applying Wisconsin substantive law.
- Plaintiffs sought to prove defect and negligence largely through an expert witness and, alternatively, through res ipsa loquitur.

## Issues

1. Whether the district court properly excluded plaintiffs’ defect expert under Federal Rule of Evidence 702.
2. Whether, absent admissible expert testimony, plaintiffs could establish a product defect, negligence, and causation through res ipsa loquitur and other circumstantial evidence (including the recall notice).

## Decision

- The Seventh Circuit affirmed the judgment for defendants.
- The court upheld the exclusion of plaintiffs’ expert under Rule 702 as a permissible exercise of the district court’s discretion.
- The court held that, without expert testimony, plaintiffs lacked proof of defect and causation in a technically complex airbag-deployment claim.
- The court rejected plaintiffs’ attempt to use res ipsa loquitur to bypass the need for expert evidence.
- The court held the recall notice, by itself, did not prove that plaintiffs’ particular vehicle had the recalled defect or that such a defect caused the deployment and injuries.

## Legal Principles

- Under Fed. R. Evid. 702, expert testimony must rest on reliable methods and a sufficient factual basis; exclusion is reviewed deferentially.
- In product-defect cases involving technical systems beyond ordinary juror knowledge, expert testimony may be necessary to prove defect and causation.
- Under Wisconsin law, res ipsa loquitur permits an inference of negligence only when the event is of a type that ordinarily does not occur absent negligence and the inference is within common understanding; it does not substitute for expert proof where technical explanation is required.
- Evidence of a product recall may show a possible defect within a product population, but it does not, without linkage to the specific unit and incident, establish defect or causation.

## Conclusion

The Seventh Circuit affirmed dismissal because plaintiffs’ expert was properly excluded under Rule 702 and, without reliable expert evidence, the airbag deployment could not be attributed to a defect or negligence through res ipsa loquitur or the recall notice alone.


Smoot v. Mazda Motors of Am., Inc., 469 F.3d 675 (7th Cir. 2006)