## Facts

- A dental patient sued her dentist for malpractice, alleging his late-1995 treatment caused a temporomandibular joint (TMJ) disorder.
- The dentist replaced two fillings and adjusted the patient’s bite during the visit in which she complained of a sore jaw.
- About two weeks later, the patient returned without an appointment complaining of jaw pain and expressing anger about the treatment.
- After learning the patient was receiving splint therapy and physical therapy, the dentist sent two checks totaling $1,175.25, each described as a goodwill gesture and not an admission of fault; the patient did not cash them.
- At trial, the plaintiff introduced evidence that the dentist carried professional liability insurance.
- The plaintiff also introduced evidence that the dentist and a defense expert were insured through the same insurance trust.
- Over objection, the trial court admitted the insurance evidence on the theory it tended to show possible bias of the defense expert.

## Issues

1. Whether CRE 411 permitted evidence that the defendant carried liability insurance and shared an insurance trust with a defense expert to show the expert’s bias.
2. Whether admitting that insurance evidence was prejudicial error requiring reversal and a new trial.

## Decision

- The Colorado Court of Appeals reversed the judgment and remanded for a new trial.
- The court held the asserted link between shared insurance-trust membership and expert bias was too speculative and attenuated to justify the prejudice of revealing liability insurance to the jury.
- The court concluded the error was not harmless because the case depended heavily on expert testimony and credibility, and the insurance references created a substantial risk the jury would draw improper inferences about liability or payment.

## Legal Principles

- CRE 411 generally bars evidence that a person was or was not insured against liability when offered to prove negligence or wrongful conduct.
- Insurance evidence may be admissible for another purpose (including bias), but only when the claimed non-liability relevance is concrete and its probative value substantially justifies the risk of unfair prejudice.
- Shared membership in the same pooled insurance arrangement, without a showing of a direct and material effect on the witness’s personal financial interests, is insufficient to establish bias for CRE 411 purposes.
- Improper admission of liability-insurance evidence is reversible when it likely affects substantial rights, particularly in professional-negligence trials where credibility and expert opinions are central.

## Conclusion

The court ordered a new trial because evidence that the defendant and a defense expert shared liability insurance was an insufficient basis to prove bias under CRE 411, and informing the jury about insurance created prejudicial risk that was not harmless.


Bonser v. Shainholtz, 983 P.2d 162 (Colo. App. 1999)