Cal. Bus. & Prof. Code § 17073 : CALIFORNIA BUSINESS AND PROFESSIONS CODE — GENERAL BUSINESS REGULATIONS — PRESERVATION AND REGULATION OF COMPETITION — UNFAIR TRADE PRACTICES — CIVIL LIABILITY — Presumptive evidence of cost

Proof of average overall cost of doing business for any particular inventory period when added to the cost of production of each article or product, as to a producer, or invoice or replacement cost, whichever is lower, of each article or product, as to a distributor, is presumptive evidence of cost of each such article or product involved in any action brought under this chapter.