Cal. Bus. & Prof. Code § 6201

(a) The rules adopted by the board of trustees shall provide that an attorney shall forward a written notice to the client prior to or at the time of service of summons or claim in an action against the client, or prior to or at the commencement of any other proceeding against the client under a contract between attorney and client which provides for an alternative to arbitration under this article, for recovery of fees, costs, or both. The written notice shall be in the form that the board of trustees prescribes, and shall include a statement of the client’s right to arbitration under this article. Failure to give this notice shall be a ground for the dismissal of the action or other proceeding. The notice shall not be required, however, prior to initiating mediation of the dispute.
The rules adopted by the board of trustees shall provide that the client’s failure to request arbitration within 30 days after receipt of notice from the attorney shall be deemed a waiver of the client’s right to arbitration under the provisions of this article.
(b) If an attorney, or the attorney’s assignee, commences an action in any court or any other proceeding and the client is entitled to maintain arbitration under this article, and the dispute is not one to which subdivision (b) of Section 6200 applies, the client may stay the action or other proceeding by serving and filing a request for arbitration in accordance with the rules established by the board of trustees pursuant to subdivision (a) of Section 6200. The request for arbitration shall be served and filed prior to the filing of an answer in the action or equivalent response in the other proceeding; failure to so request arbitration prior to the filing of an answer or equivalent response shall be deemed a waiver of the client’s right to arbitration under the provisions of this article if notice of the client’s right to arbitration was given pursuant to subdivision (a).
(c) Upon filing and service of the request for arbitration, the action or other proceeding shall be automatically stayed until the award of the arbitrators is issued or the arbitration is otherwise terminated. The stay may be vacated in whole or in part, after a hearing duly noticed by any party or the court, if and to the extent the court finds that the matter is not appropriate for arbitration under the provisions of this article. The action or other proceeding may thereafter proceed subject to the provisions of Section 6204.
(d) A client’s right to request or maintain arbitration under the provisions of this article is waived by the client commencing an action or filing any pleading seeking either of the following:
1. (1) Judicial resolution of a fee dispute to which this article applies.
2. (2) Affirmative relief against the attorney for damages or otherwise based upon alleged malpractice or professional misconduct.
(e) If the client waives the right to arbitration under this article, the parties may stipulate to set aside the waiver and to proceed with arbitration.