California Code, Health and Safety Code - HSC § 132000

(a) Except as provided in Section 132004, a person who manufactures a prescription drug shall not offer in the state a discount, repayment, product voucher, or other reduction in an individual's out-of-pocket expenses associated with his or her health insurance, health care service plan, or other health coverage, including, but not limited to, a copayment, coinsurance, or deductible, for a prescription drug if a lower cost generic drug is covered under the individual's health insurance, health care service plan, or other health coverage on a lower cost-sharing tier that is designated to be therapeutically equivalent as indicated by the United States Food and Drug Administration's “Approved Drug Products with Therapeutic Equivalence Evaluations.”

(b) The prohibition in subdivision (a) shall not apply to a branded prescription drug, until the time that the first drug designated in the United States Food and Drug Administration's “Approved Drug Products with Therapeutic Equivalence Evaluations” as therapeutically equivalent to that branded prescription drug has been nationally available for three calendar months.