California Code, Corporations Code - CORP § 15910.03

(a) A derivative action may be maintained only by a person that is a partner at the time the action is commenced and:

(b) Notwithstanding the foregoing, any partner who does not meet the foregoing requirements may nevertheless be allowed in the discretion of the court to maintain the action on a preliminary showing to and determination by the court, by motion and after a hearing, at which the court shall consider such evidence, by affidavit or testimony, as it deems material that (1) there is a strong prima facie case in favor of the claim asserted on behalf of the partnership, (2) no other similar action has been or is likely to be instituted, (3) the plaintiff acquired the shares before there was disclosure to the public and to the plaintiff of the wrongdoing of which plaintiff complains, (4) unless the action can be maintained the defendant may retain a gain derived from the defendant's willful breach of a fiduciary duty, and (5) the requested relief will not result in unjust enrichment of the partnership or any partner.