The Community Hospital Association (P) granted staff privileges to D in October 1964. D performed numerous craniotomies. A review of those craniotomies indicated that tissue samples from many of the patients appeared normal. D was reprimanded and required to obtain consultations before performing craniotomies if the relevant radiographic evidence did not clearly establish pathology. In March 1968, P's tissue committee received a report that fourteen of twenty-eight tissue samples taken from D's neurosurgery patients were completely normal and that nine of the remaining fourteen samples indicated only low-grade disease. An expert testified that one normal tissue of 100 tissue samples was an acceptable ratio and that two normal tissues out of twenty-eight samples would require investigation. D performed a craniotomy on Esther Cortez which resulted in injury to Cortez. Cortez filed a civil action against D and P. Cortez alleged that d negligently diagnosed her and that P negligently continued D's staff privileges when it knew or should have known that he was incompetent and that P negligently allowed D to perform unnecessary surgery. The claim against D was severed. Cortez and P agreed to a settlement of $150,000. P and its subrogee, Western Insurance Company (Western), filed this indemnity action against D, alleging that d's negligence was the active and primary cause of Cortez's injuries while P's negligence was passive and secondary. The trial court found that under common-law principles of indemnity and joint-and-several liability, D could be held responsible for all Cortez’s damages. The trial court entered judgment for Western. D appealed and the appeals court affirmed. D appealed.