Cal. Bus. & Prof. Code § 23358.2
Notwithstanding any other provision of this division, a winegrower or brandy manufacturer, at his or her licensed premises where the sale of wine or brandy is authorized or permitted, when selling to consumers, may sell only wine or brandy which is produced or bottled by such licensee, or wine or brandy which is produced for or is produced and packaged for such licensee, and which is sold under a brand name owned by such licensee. The rights and privileges of a winegrower or brandy manufacturer to be issued and to hold an off-sale beer and wine license for any of his or her licensed premises, or for other premises, shall not in any way be changed or affected, or be construed to be changed or affected, by the provisions of this section.
Ca. Bus. and Prof'l. Code § 23358.2