## Facts

- Phyllis Thomas developed acute pain between her shoulder blades with left arm pain and numbness in her left thumb, index, and middle fingers.
- Physicians diagnosed a left-sided C6–C7 disc herniation and obtained a neurosurgical consultation from Albert V. Metz, Jr., M.D.
- Dr. Metz confirmed the diagnosis and recommended surgery to remove disc fragments compressing the spinal cord and the left C-7 nerve root.
- With Thomas’s consent, Dr. Metz performed cervical surgery, removed disc fragments, and placed a hip bone plug to fuse the vertebrae.
- Postoperatively, Thomas developed similar pain on her right side; testing indicated the bone plug encroached on the right C-7 nerve root.
- A second surgery was performed to relieve the right-sided nerve root encroachment.
- Thomas sued Dr. Metz for medical malpractice, alleging the surgery was improperly performed and not medically necessary.
- At trial, Dr. Metz presented expert testimony from neurologic specialists who reviewed hospital records and pretrial depositions (including Dr. Metz’s deposition) and opined the surgery was necessary and met the applicable standard of care.
- The jury returned a verdict for Dr. Metz.

## Issues

1. Whether the trial court erred by admitting defense expert opinions that relied in part on the defendant physician’s deposition and other experts’ opinions, allegedly not the type of data reasonably relied upon by experts under W.R.E. 703.
2. Whether the trial court reversibly erred by declining to require disclosure of the experts’ underlying facts or data before the opinions were given, and by refusing to strike the opinions after the bases were explored.

## Decision

- The Wyoming Supreme Court affirmed the judgment on the jury’s verdict for Dr. Metz.
- The court held the challenged expert opinions were admissible because the materials relied upon (including medical records and depositions) could constitute data reasonably relied upon by experts in the field.
- The court held the trial judge acted within discretion in managing when and how the bases for expert opinions were disclosed and tested.
- The court found no abuse of discretion and no showing of prejudice warranting reversal.

## Legal Principles

- Under W.R.E. 703, an expert may base an opinion on facts or data reasonably relied upon by experts in the particular field, even if the information is not itself admissible.
- In medical cases, experts may reasonably rely on materials such as hospital records, diagnostic testing, and pretrial deposition testimony in forming opinions.
- Weaknesses in an expert’s factual basis generally affect weight, not admissibility, when the basis is exposed through cross-examination for the jury’s evaluation.
- Trial courts have broad discretion over evidentiary rulings concerning expert testimony, including the timing and scope of disclosure of underlying data; reversal requires a clear abuse of discretion and resulting prejudice.
- In most medical malpractice actions, the plaintiff bears the burden of producing expert testimony to establish a prima facie case of negligence.

## Conclusion

The court upheld a defense verdict in a medical malpractice case, ruling that defense experts could form opinions from medical records and deposition materials under W.R.E. 703 and that the trial court’s control over disclosure and testing of the opinions’ bases was discretionary absent a prejudicial abuse of discretion.


Thomas v. Metz, 714 P.2d 1205 (Wyo. 1986)