As explained by the Second Department in Cipriano v. City of New York,
In a slip and fall case, a defendant may establish its prima facie entitlement to judgment as a matter of law by submitting evidence that the plaintiff cannot identify the cause of his or her fall. If a plaintiff is unable to identify the cause of a fall, any finding of negligence would be based upon speculation. That does not mean that a plaintiff must have personal knowledge of the cause of his or her fall. Rather, it means only that a plaintiff’s inability to establish the cause of his or [her] fall—whether by personal knowledge or by other admissible proof—is fatal to a cause of action based on negligence.
The court reversed the lower court’s order granting summary judgment to defendants:
Here, the defendants failed to establish, prima facie, that the plaintiff could not identify the cause of her fall. In support of the motion and cross motion, the defendants primarily relied upon the transcript of the plaintiff’s hearing testimony pursuant to General Municipal Law § 50-h. This transcript failed to eliminate triable issues of fact as to whether the plaintiff could establish the cause of her fall, as she testified that there was ice at the location of her fall.