How truthful must a lawyer be in mediation?

Revised Rules of Professional Conduct (RPC) go into effect in Missouri on July 1, 2007. Several of these rules address the candor that a lawyer must use in representing a client in mediation. The comment to Rule 4-2.4 mentions that lawyers representing clients in alternative dispute resolution process are governed by RPC., and that lawyers have an obligation of candor to both the neutral and other parties. The level of truthfulness before a "tribunal" (court or binding arbitration governed by Rule 4-3.3), however, is higher than the candor required in mediation (governed by Rule 4-4.1) For mediation (Rule 4-4.1) a lawyer is required to be truthful, "shall not knowingly make a false statement of material fact or law," but generally has "no affirmative duty to inform" other parties of relevant facts. Estimates of price or value or a party's intentions regarding settlement may or may not be fact statements, depending on the circumstances. A certain amount of "puff talk" is allowed. The lawyer must only disclose a material fact if avoiding to do so would assist a criminal or fraudulent act by the client. Before a tribunal a lawyer shall not knowingly make a false statement of any fact or law or fail to disclsoe legal authority directly adverse to the client when another party does not disclose it. Before a tribunal a lawyer may not offer evidence the lawyer knows to be false (the tolerance for puff talk is less).

HOW HAVE YOU HANDLED A SITUATION IN MEDIATION WHERE YOU THOUGHT A PARTY OR THE PARTY'S LAWYER WAS NOT TRUTHFUL?