California Code, Government Code - GOV § 53070

(a) No city, county, or district may enact an ordinance prohibiting or regulating the playing of duplicate bridge.  Duplicate bridge is defined as the card game of bridge played at tournaments conducted by bridge associations, bridge clubs or bridge studios which do not permit wagering or gambling on the outcome of the bridge games played in their tournaments, or otherwise, either by the rules of said associations or the rules of the individual bridge clubs and bridge studios.

(b) The person or persons in charge of any duplicate bridge tournament shall post, or cause to be posted, in the place where the tournament is conducted and in such manner as to be visible to participants, the rule of the association, club, or studio which prohibits wagering or gambling.  Such person or persons shall permit inspection of the rules of the association, club, or studio by law enforcement officers and licensing officials of the county or city in which the tournament is conducted.