What is the burden of proof for a plaintiff in a psychotherapist-patient relationship?

Once the claimant establishes the preliminary facts of a psychotherapist-patient relationship, the burden of proof shifts to the opponent of the privilege. To obtain disclosure, the opponent must rebut the statutory presumption of confidentiality set forth in section 917: "Whenever a privilege is claimed on the ground that the matter sought to be disclosed is a communication made in confidence in the course of the . . . psychotherapist-patient . . . relationship, the communication is presumed to have been made in confidence and the opponent of the claim of privilege has the burden of proof to establish that the communication was not confidential." ( 917; see Mahoney v. Superior Court, supra, 142 Cal.App.3d at p. 940.) Alternatively, the opponent of the privilege may show that the privilege has been waived under section 912, or that the material sought falls within one of the exceptions to the psychotherapist-privilege codified at sections 1016 through 1027.