California Code, Food and Agricultural Code (Formerly Agricultural Code) - FAC § 32732

No prosecution which is based upon a sample of milk, cream, a product of milk or cream, or a product resembling milk products shall be had unless a duplicate of the sample is left with the accused.

Samples which are taken in connection with the establishment of proof of fraudulent manipulation of the tests for the basis of payment for milk or cream, need not, however, be given to the accused.