Know your audience. Some parties believe the Mediation Summary is prepared exclusively for the mediator’s benefit to persuade the mediator. Others prepare these summaries for the purpose of satisfying their clients. Simply because the mediator may be convinced of the merits of a case or defense, or the client is satisfied with the tone and tenor of the Summary, does not mean the Mediation Summary will have accomplished an essential purpose.
One of the main purposes of the Mediation Summary that is exchanged is to tell a compelling and credible story in a professional manner (more on this in the "Litigation Advocacy and Mediation Advocacy are Different" and "Think 'Team' and Harness the Power of Positive Conflict" tips) that underscores to the opposing party its weaknesses and risks should the matter not resolve at the mediation. A compelling story, based upon the law and the facts of the case, which is told in a concise manner, is a precious opportunity to induce the opposing party to reconsider its BATNA.
If there is a need to submit additional information to the mediator, which can be for the mediator’s eyes only, that should certainly be explored. However, exchanged summaries, which are read both by opposing counsel and their clients, can have a significant positive impact upon maximizing one’s success during the mediation.