Paula E. Phillips (plaintiff) was admitted to Desert Hospital (hospital) (defendant), a public hospital, on September 11, 1983, for surgery that Phillips and her husband (plaintiff) alleged was medically unnecessary and negligently performed and caused them both to suffer damages. On April 6, 1984, the Phillipses’ attorney mailed the hospital a letter notifying the hospital of the Phillipses’ intention to sue the hospital within 90 days. That letter was sent to constitute a 364 notice, which is required pre-suit in medical-malpractice cases against healthcare providers. The Phillipses’ attorney, however, was unaware that the hospital was a public entity that instead required specific claim-presentation requirements under the state Tort Claims Act (act). When no response to the letter was received, the Phillipses filed a medical-malpractice action against the hospital and Paula’s treating physician. The hospital demurred on grounds that the complaint failed to state a cause of action because it failed to allege compliance with the act’s claim-presentation requirements. The trial court granted the demurrer and dismissed the case. The Phillipses appealed. The court of appeal affirmed. The Phillipses appealed and argued that their 364 notice was a defective claim under the act’s claim-presentation requirements that triggered a provision requiring the hospital to comply with the act’s notice and defense-waiver provisions to give the Phillipses notice of their claim’s insufficiency or waive any defenses thereto.