Cal. Bus. & Prof. Code § 6341

Any board of law library trustees may establish and maintain a branch of the law library in any city in the county, other than the county seat, in which a session of the superior court is held. In any city constituting the county seat, any board of law library trustees may establish and maintain a branch of the law library at any location therein where four or more judges of the superior court are designated to hold sessions more than 10 miles distant from the principal office of the court. In any city and county any board of law library trustees may establish and maintain branches of the law library. A branch is in all respects a part of the law library and is governed accordingly.