## Facts

- Eva Diaz underwent a transvaginal sonogram at New York Downtown Hospital performed by a male sonography technician.
- Diaz alleged the technician sexually assaulted her while they were alone in the examination room.
- Diaz sued the hospital for negligent hiring, training, supervision, and retention of the technician.
- The hospital moved for summary judgment, asserting it lacked prior knowledge or notice of any propensity by the technician to commit sexual assault.
- Diaz opposed with an expert affirmation from a board-certified radiologist asserting the hospital deviated from the standard of care by lacking a policy requiring a female staff member to be present during transvaginal sonograms on female patients.
- The expert relied on guidelines from national professional organizations recommending a female examiner or chaperone for vaginal sonograms, but did not provide evidence that such recommendations were generally adopted or customary in comparable facilities.

## Issues

1. Whether an expert affidavit relying on professional guidelines recommending a female chaperone, without evidence of general adoption or customary practice, is sufficient to raise a triable issue of fact on the applicable standard of care and defeat summary judgment on negligent supervision.

## Decision

- The Court of Appeals affirmed the Appellate Division’s order granting summary judgment to the hospital and dismissing the complaint against it.
- The court held the expert affirmation did not establish an accepted industry standard requiring a chaperone during transvaginal sonograms.
- The court concluded the expert’s opinion lacked an adequate factual foundation and was insufficient to create a triable issue of fact.

## Legal Principles

- Professional or clinical guidelines, standing alone, do not establish the legal standard of care absent proof they reflect an actual, accepted practice or custom in the relevant professional community.
- An expert opinion offered to defeat summary judgment must rest on a concrete factual basis; conclusory assertions that recommendations equal the standard of care are insufficient.
- Where a negligent supervision theory depends on showing deficient supervisory procedures (rather than notice of an employee’s propensity), the plaintiff must present competent evidence of the applicable standard and its breach.

## Conclusion

Because the plaintiff’s expert relied on recommendations without evidentiary support that they were generally accepted and implemented as customary practice, the affidavit failed to show an applicable standard of care or raise a triable issue of negligence, and dismissal against the hospital was affirmed.


Diaz v. N.Y. Downtown Hosp., 99 N.Y.2d 542, 784 N.E.2d 68 (N.Y. 2002)