## Facts

- Two automobiles collided at an unmarked rural intersection in Illinois.
- The Deaver vehicle (a Buick) traveled south; the Hickox vehicle (a Falcon) traveled east.
- Tall corn near the intersection obstructed both drivers’ views as they approached.
- After impact, the Hickox vehicle left approximately 39 feet of skid marks and traveled another 20–25 feet.
- The Deaver vehicle was struck on its right side, overturned, and came to rest on its top about 17 feet from the intersection’s center.
- A state highway police officer who investigated after the crash testified to an opinion about the vehicles’ pre-collision speed, based largely on physical observations and his general experience.
- The officer acknowledged his speed estimate was speculative and not derived from a scientific or technical method.
- Over objection, the trial court admitted the officer’s speed-opinion testimony; the jury returned verdicts for the decedents’ estates and against Hickox.

## Issues

1. Whether a police officer’s opinion on pre-impact vehicle speed, based on post-accident observations and general experience without a demonstrated scientific or technical methodology, is admissible as expert opinion evidence.
2. Whether admitting such speculative speed-opinion testimony on a central liability issue requires reversal.

## Decision

- The appellate court held the trial court erred by admitting the officer’s speed-opinion testimony.
- The court found the opinion speculative and unsupported by specialized skills, training, or articulated scientific methods beyond ordinary juror reasoning.
- Because speed was central to negligence liability, the error was prejudicial.
- The judgments for the plaintiffs were reversed and the cause remanded for further proceedings.

## Legal Principles

- Expert-type opinion testimony is admissible only when the witness is shown to possess specialized knowledge or skill beyond that of the average juror and the opinion rests on a reliable, articulated basis.
- A police officer’s status and general accident-investigation experience, standing alone, do not establish an adequate foundation to estimate vehicle speed from skid marks and post-collision physical evidence.
- Opinion testimony that is conceded to be speculative, and not tied to scientific or technical methods the factfinder can evaluate, is inadmissible—particularly when directed to a core issue such as speed and negligence.

## Conclusion

The appellate court reversed wrongful-death judgments because the trial court admitted a state trooper’s speculative speed estimate without a demonstrated technical foundation, and the resulting prejudice on a central liability question required a new trial.


Deaver v. Hickox, 81 Ill. App. 2d 79, 224 N.E.2d 468 (Ill. App. Ct. 3d Dist. 1967)