## Facts

- Aiken was diagnosed with paranoid schizophrenia by Dr. Clary, who recommended insulin shock therapy and electroshock therapy.
- Dr. Clary told Aiken the insulin treatment would “put him to sleep” and warned of a risk comparable to anesthesia if the patient overreacted.
- After consulting his wife and family physician, Aiken signed a written authorization permitting Dr. Clary and assistants to administer insulin and/or electroshock therapy and related supplemental treatment.
- During a series of insulin shock treatments over roughly ten days, Aiken experienced a prolonged coma or delayed awakening.
- Aiken alleged the coma caused permanent brain damage and total disability.
- Aiken sued for malpractice, including a claim that Dr. Clary negligently failed to inform him of the hazards and risks of insulin shock therapy.
- Aiken presented expert testimony describing the treatment, its dangers, and his injuries, but did not present expert testimony on what a reasonably careful physician in similar circumstances would disclose to a patient like Aiken.
- The jury returned a verdict for Dr. Clary, and the trial court denied Aiken’s motion for new trial.

## Issues

1. In a malpractice claim based on failure to disclose treatment risks, must the plaintiff present expert testimony establishing what a reasonably prudent physician would disclose under similar circumstances?
2. Did the trial court err by restricting voir dire questions aimed at identifying juror bias based on connections with the defendant’s liability insurer?

## Decision

- The Supreme Court of Missouri reversed and remanded for a new trial.
- The court held that the duty to disclose in informed-consent-type malpractice cases is measured by a professional standard and must be proved by expert medical testimony.
- The court concluded that Aiken’s proof at trial was insufficient under that standard because it lacked expert evidence of the customary or reasonable disclosure practice for psychiatrists in comparable circumstances.
- The court also held the trial court improperly curtailed good-faith voir dire concerning potential juror connections to the defendant’s liability insurer, impairing the ability to detect bias.
- The remand allowed Aiken an opportunity to present expert testimony on the disclosure standard and to conduct voir dire consistent with the court’s ruling.

## Legal Principles

- A physician’s disclosure obligation is governed by a professional (physician-oriented) standard: what a reasonably careful practitioner in the same field and under similar circumstances would disclose.
- Because disclosure decisions involve medical judgment beyond common lay knowledge, expert testimony is generally required to establish the applicable standard of disclosure and a deviation from it.
- In civil jury trials, voir dire may include good-faith inquiries into prospective jurors’ relationships with a party’s liability insurer to uncover bias; undue restriction of such inquiry is reversible error.

## Conclusion

The court required expert testimony to prove the physician-based standard for risk disclosure in informed-consent malpractice claims and ordered a new trial because the plaintiff lacked that proof under the clarified rule and because voir dire was improperly limited as to possible insurer-related juror bias.


Aiken v. Clary, 396 S.W.2d 668 (Mo. 1965)