California Code, Business and Professions Code - BPC § 23006

“Beer” means any alcoholic beverage obtained by the fermentation of any infusion or decoction of barley, malt, hops, or any other similar product, or any combination thereof in water, and includes ale, porter, brown, stout, lager beer, small beer, and strong beer, but does not include sake, known as Japanese rice wine.  Beer may be produced using the following materials as adjuncts in fermentation:  honey, fruit, fruit juice, fruit concentrate, herbs, spices, and other food materials.  Beer aged in an empty wooden barrel previously used to contain wine or distilled spirits shall be defined exclusively as “beer” and shall not be considered a dilution or mixture of any other alcoholic beverage.