Ybarra (plaintiff) consulted Dr. Tilley (defendant) about stomach pains. Tilley diagnosed Ybarra with appendicitis and scheduled an appendectomy to be performed by Dr. Spangard (defendant), at a hospital owned by Dr. Swift (defendant). Before the operation, Ybarra was placed on the operating table by Dr. Reser (defendant), an anesthetist. Dr. Reser positioned Ybarra against two “hard objects” that supported his neck and shoulders, and administered anesthesia. After the operation, Ybarra woke up to severe pain in his neck and right shoulder. The pain increased after Ybarra left the hospital, resulting in paralysis and loss of function in his right arm. Ybarra was examined by two other doctors who stated the cause of his injury as being trauma from pressure or strain on his neck and right arm. Ybarra brought suit against all doctors involved under a theory of res ipsa loquitur, meaning an inference of negligence on the part of the doctors should arise from the fact of his injury. The doctors argued that where there are several defendants or instrumentalities involved in an injury-producing act, and the injury cannot actually be traced to any one defendant or instrumentality, the doctrine of res ipsa loquitur does not apply. The trial court granted a judgment of nonsuit for the doctors, and Ybarra appealed.