CA Health & Safety Code Section 114079

(a)

Except as specified in subdivision (b), after being served or sold and in the possession of a consumer, food that is unused or returned by the consumer shall not be offered as food for human consumption.

(b)

A container of food that is not potentially hazardous may be transferred from one consumer to another if the food is dispensed so that it is protected from contamination and the container is closed between uses, such as a narrow-neck bottle containing catsup, steak sauce, or wine, or if the food, such as crackers, salt, or pepper, is in an unopened original package and is maintained in sound condition, and if the food is checked periodically on a regular basis.