(a) A privilege under section 658H-4 may be waived in a record or orally during a proceeding if it is expressly waived by all parties to the mediation and:
(1) In the case of the privilege of a mediator, it is expressly waived by the mediator; and
(2) In the case of the privilege of a nonparty participant, it is expressly waived by the nonparty participant.
(b) A person who discloses or makes a representation about a mediation communication that prejudices another person in a proceeding is precluded from asserting a privilege under section 658H-4, but only to the extent necessary for the person prejudiced to respond to the representation or disclosure.
(c) A person who intentionally uses a mediation to plan, attempt to commit or commit a crime, or to conceal an ongoing crime or ongoing criminal activity is precluded from asserting a privilege under section 658H-4.