Existing law, the Knox-Keene Health Care Service Plan Act of 1975, provides for the licensure and regulation of health care service plans by the Department of Managed Health Care, and makes a willful violation of the act a crime. Existing law provides for the regulation of health insurers by the Department of Insurance. Existing law sets forth specified prior authorization and step therapy limitations for health care service plans and health insurers. This bill would prohibit a health care service plan contract or health insurance policy issued, amended, or renewed on or after January 1, 2027, from imposing prior authorization, step therapy, or other utilization review for a drug approved for the treatment of a rare disease if the drug is prescribed by a specialist with expertise in the condition or disease being treated and the specialist has determined the drug is medically necessary, unless a biosimilar, interchangeable biologic, or generic version of the drug is available. Because a willful violation of this provision by a health care service plan would be a crime, the bill would impose a state-mandated local program. The California Constitution requires the state to reimburse local agencies and school districts for certain costs mandated by the state. Statutory provisions establish procedures for making that reimbursement. This bill would provide that no reimbursement is required by this act for a specified reason.