Ohio Rev. Code § 2710.04: Waiver of privilege - privilege precluded.

(A) A privilege under section 2710.03 of the Revised Code may be waived in a record or orally during a proceeding if it is expressly waived by all mediation parties and by whichever of the following is applicable:

(1) In the case of the privilege of a mediator, it is expressly waived by the mediator.

(2) In the case of the privilege of a nonparty participant, it is expressly waived by the nonparty participant.

(B) A person that discloses or makes a representation about a mediation communication that prejudices another person in a proceeding is precluded from asserting a privilege under section 2710.03 of the Revised Code, but only to the extent necessary for the person prejudiced to respond to the representation or disclosure.

(C) A person that 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 2710.03 of the Revised Code.