## Facts

- Kathleen States underwent surgery at Our Lady of Lourdes Hospital to remove an ovarian cyst while under anesthesia.
- During the procedure, States’ right arm was placed on an arm board; she later alleged it was negligently hyperabducted beyond 90 degrees for an extended period.
- No operative record noted a mishap, and medical staff did not report contemporaneous awareness of an injury-causing event.
- After surgery, States developed significant right arm and shoulder pain and dysfunction, diagnosed as brachial plexus-related injury conditions.
- States offered expert medical testimony that such brachial plexus traction injuries ordinarily do not occur during this type of procedure absent a deviation from accepted medical care, and that the injury was caused by failure to maintain and protect proper arm positioning during surgery.

## Issues

1. In a medical malpractice action, may a plaintiff use expert medical testimony to establish the res ipsa loquitur requirement that the event is of a kind that ordinarily does not occur in the absence of negligence when lay jurors lack the specialized knowledge to make that determination unaided?
2. If so, did plaintiff’s expert proof raise a triable issue of fact under res ipsa loquitur sufficient to defeat summary judgment?

## Decision

- The Court of Appeals reversed the Appellate Division.
- The court held that expert medical testimony may be used to support the res ipsa loquitur inference, including the foundational showing that the occurrence ordinarily does not happen without negligence.
- The court reinstated the trial court’s denial of the anesthesiologist’s summary judgment motion, permitting the case to proceed with a res ipsa loquitur theory supported by expert evidence.

## Legal Principles

- Res ipsa loquitur in New York permits (but does not compel) an inference of negligence when: (1) the event is of a kind that ordinarily does not occur without negligence; (2) the instrumentality causing the injury was within the defendant’s exclusive control; and (3) the injury was not due to any voluntary action or contribution by the plaintiff.
- The “ordinarily does not occur without negligence” element is not limited to matters within lay experience; it may be established through qualified expert testimony in medically complex cases.
- Expert testimony may supply the factual basis for the jury’s inference by explaining what ordinarily occurs in medical practice, while leaving the ultimate decision to draw (or reject) the inference to the factfinder.
- On summary judgment, where expert submissions support each res ipsa element and create a triable issue, the court should not remove the inference question from the jury.

## Conclusion

The court held that expert medical evidence can establish res ipsa loquitur’s foundational requirement that an injury-producing event ordinarily does not occur absent negligence, and it allowed the malpractice claim to proceed to trial because the plaintiff’s experts raised a triable issue supporting a permissive inference of negligence.


States v. Lourdes Hosp., 100 N.Y.2d 208 (N.Y. 2003)