California Code, Business and Professions Code - BPC § 23377

A wine broker's license authorizes the person to whom issued to act as a wine broker, for a fee or commission, in the purchase of wine for or on behalf of a person within or without this State authorized to buy wine for purposes of resale and in the sale of wine for or on behalf of a person, other than a retail licensee, licensed to sell wine within the State.  A wine broker shall not buy or sell any wine for his own account, take or deliver title to wine, or receive or store any wine in his own name in this State.  A wine broker shall not offer to sell, agree to offer to sell, or sell any wine unless he first has a bona fide authorization to do so from a person, other than a retail licensee, licensed to sell wine in this State.  A wine broker shall not offer to buy, agree to buy, agree to offer to buy, or buy any wine unless he first has a bona fide authorization to do so from a person within or without this State authorized to buy wine for purposes of resale.  The exercise of the privileges granted by the wine broker's license are subject to such rules and conditions as the department deems necessary and proper.