Cal. Gov. Code § 71637.1

For purposes of this article, in addition to those rules and regulations that a trial court may adopt pursuant to, and in the same manner as set forth in, Section 71636, any trial court may adopt reasonable rules and regulations providing for designation of the management and confidential employees of the trial court and restricting those employees from representing any employee organization that represents other employees of the trial court, on matters within the scope of representation. Except as specifically provided otherwise in this article, this section does not otherwise limit the right of employees to be members of, and to hold office in, an employee organization.