Cal. Health & Safety Code § 1451

(a) Except as otherwise provided in this section, the board shall not let the care, maintenance, or attendance of the indigent sick or dependent poor by contract to any person.
(b) The board may secure for the indigent sick, and other persons admissible to the county hospital, at an agreed rate, hospital service, or any portion thereof, from any public or private hospital, clinic, rest home, sanitarium, or other suitable facility, or from any corporation formed under Section 9201 of the Corporations Code or under Chapter 11A (commencing with Section 11491) of Part 2of Division 2 of the Insurance Code that operates in the state, in the following cases:
1. (1) Cases of unusual difficulty.
2. (2) Cases that require treatment, or hospital services, or the use of facilities not immediately available in the county hospital.
3. (3) Cases requiring emergency care or continued treatment after the emergency has ceased to exist.
(c) As used in this section, “hospital service” includes medical, surgical, radiological, laboratory, nursing service, convalescent care, and the furnishing of the necessary professional personnel, equipment, and facilities to manage the needs of patients on a continuing basis in accordance with accepted medical standards, with a staff of professional nursing personnel who are assigned and available under a clear and definite responsibility to the institution rendering the service for the provision of services to the patients, and any other care, service, or supplies that may be necessary for the treatment of the sick or injured.
(d) The county may also contract with licensed boarding homes for 24-hour care for dependent children under the age of 18 years when suitable facilities are not otherwise available in any institution or establishment maintained and operated by the county.
(e) The county may also contract for medical treatment of persons admissible to the county hospital with any licensed physician and surgeon, or a corporation operating under Section 9201 of the Corporations Code.
(f) The county may also contract for health care services when the board determines that the hospital services or any portion thereof rendered by the county hospital should be coordinated with those provided by any other source.