One critical quality is the ability to keep confidential what the mediator is told during the private sessions.
The mediator must be rock-solid on keeping this promise that he or she makes to the parties in the agreement to mediate: No disclosure of your client’s secrets by a hint to the other party, nor in answer to a question from them, nor by a nod and a wink… not in any way, unless the party imparting the secret gives the mediator permission in advance to disclose it to the other party.
The parties must be utterly confident that they can trust the mediator with their secrets. Only then will they be candid in private sessions in which the mediator participates. Candour is essential for productive negotiations.
Yet anecdotal evidence suggests that many inexperienced mediators simply blurt out one parties’ secrets to the other party. Inevitably, the party imparting the secret information finds out that it has been disclosed to the other party. All trust in the mediator is destroyed and he or she might as well go home.