(a) For each matter referred for ADR procedures, the ADR director shall assign a mediator, unless the participants agree upon the use of a private mediator. The ADR director may assign a substitute or additional mediator to a proceeding as the ADR director deems necessary.(b) A private mediator may be hired for commission ADR procedures provided that:(1) the participants unanimously agree to use a private mediator;(2) the participants unanimously agree to the selection of the person to serve as the mediator;(3) the mediator agrees to be subject to the direction of the commission's ADR director and to all time limits imposed by the director, the judge, statute, or regulation.(c) If a private mediator is used, the costs for the services of the mediator shall be apportioned equally among the participants, unless otherwise agreed upon by the participants, and shall be paid directly to the mediator. In no event, however, shall any such costs be apportioned to a governmental subdivision or entity that is a statutory party to the hearing.(d) All mediators in commission mediation proceedings shall subscribe to the ethical guidelines for mediators adopted by the ADR Section of the State Bar of Texas.