(a) A privilege under section 5715 of this title 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 which prejudices another person in a proceeding is precluded from asserting a privilege under section 5715 of this title 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 conceal an ongoing crime or ongoing criminal activity, may not assert a privilege under section 5715 of this title.