(a) A communication or a writing, as defined in Section 250, that is made or prepared for the purpose of, or in the course of, or pursuant to, a mediation or a mediation consultation, is not made inadmissible, or protected from disclosure, by provisions of this chapter if either of the following conditions is satisfied:
(1) All persons who conduct or otherwise participate in the mediation expressly agree in writing, or orally in accordance with Section 1118, to disclosure of the communication, document, or writing.
(2) The communication, document, or writing was prepared by or on behalf of fewer than all the mediation participants, those participants expressly agree in writing, or orally in accordance with Section 1118, to its disclosure, and the communication, document, or writing does not disclose anything said or done or any admission made in the course of the mediation.
(b) For purposes of subdivision (a), if the neutral person who conducts a mediation expressly agrees to disclosure, that agreement also binds any other person described in subdivision (b) of Section 1115.