California Code, Welfare and Institutions Code - WIC § 14133.65

Prior authorization for the use of nonemergency medical transportation services by patients to and from dialysis treatment shall be approved for a period of up to one year when the patient has received the transportation services for the immediately preceding 12 months, the request for renewed prior authorization is supported by a physician's certification that the patient's condition is unlikely to improve during the period covered by the request, and the department has determined that there is medical necessity for the service.  Whenever there is a change or improvement in the patient's condition, the physician shall submit a new certification to the department.