California Code, Probate Code - PROB § 1970

(a) The Legislature finds that unwarranted petitions, applications, or motions other than discovery motions after a conservatorship has been established create an environment that can be harmful to the conservatee and are inconsistent with the goal of protecting the conservatee.

(b) Notwithstanding Section 391 of the Code of Civil Procedure, if a person other than the conservatee files a petition for termination of the conservatorship, or instruction to the conservator, that is unmeritorious or intended to harass or annoy the conservator, and the person has previously filed pleadings in the conservatorship proceedings that were unmeritorious or intended to harass or annoy the conservator, the petition shall be grounds for the court to determine that the person is a vexatious litigant for the purposes of Title 3A (commencing with Section 391) of Part 2 of the Code of Civil Procedure. For these purposes, the term “new litigation” shall include petitions for visitation, termination of the conservatorship, or instruction to the conservator.