A mediator panel may be used in collective bargaining when: the Montgomery Commission and the employee organization agree to mediation; or an impasse results, and the Montgomery Commission or the employee organization requests mediation. The Montgomery Commission and the employee organization shall: each choose one mediator from a list supplied by the American Arbitration Association or the Federal Mediation and Conciliation Service; and together choose a third mediator from a list supplied by the American Arbitration Association or the Federal Mediation and Conciliation Service. If the Montgomery Commission and the employee organization cannot agree on a jointly appointed mediator, the labor relations administrator shall choose the third mediator. The Montgomery Commission and the employee organization shall share the costs of mediation equally.