In Truck Ins. Exchange v. County of Los Angeles (2002) 95 Cal.App.4th 13, a county and a hospital (Santa Marta) entered into an agreement by which Santa Marta would provide services for patients referred by the county. The county agreed, among other things, to refer only low-risk patients and further agreed to indemnify Santa Marta for claims or damages. (Id. at p. 16.) The county later referred a high-risk patient, Panduro, to Santa Marta, who was injured, as was her baby, during a breech birth. The Panduros sued the county and Santa Marta for her injuries. (Ibid.) The county refused to defend Santa Marta, so Santa Marta's insurer (Truck) provided a defense. (Id. at p. 17.) The jury found that the county was negligent in causing the Panduros' injuries, but Santa Marta was not. (Ibid.) Truck thereafter sued the county in subrogation, based on the county's contractual obligation to indemnify and defend Santa Marta in the medical malpractice action. (Id. at p. 18.) On appeal, the court held that Truck was entitled to equitable subrogation, because the county had caused the underlying loss. "County's negligent referral of a high-risk patient to Santa Marta resulted in injury to the Panduros, precipitated the Panduros' lawsuit against County and Santa Marta, and made it necessary for Santa Marta to incur defense costs. Since Santa Marta was not at fault and County's misconduct was a substantial factor in causing Santa Marta to incur defense costs, we conclude that County is primarily liable and equitably should bear the entire obligation. We therefore conclude that Truck has established a right of subrogation against County subject to any applicable defenses that County may have." (Truck, supra, 95 Cal.App.4th at p. 27.)