As every mediation advocate must know by now, the California Supreme Court has locked down mediation confidences from attack at every turn. There can be no implied waiver of Evidence Code section 1119's protections and you cannot be estopped to assert it (Simmons v. Ghaderi) (.pdf of the opinion here).
Your client may have been coerced into signing off on the agreement; may not have understood what she was signing; or her assent could have been induced by your opponent's material misrepresentations of fact. Your client's insurance carrier may be guilty of actionable bad faith during the course of the mediation. Too bad. The mediation proceeding is given greater protection than given to penitents in a confessional.
But you can inadvertently expressly waive the protections of mediation confidentiality if you've carelessly crafted your own confidentiality agreement.
California's Second District Court of Appeal held in Thottam (.pdf of opinion here) that a party's confidentiality agreement did just that -- waived the protection -- permitting one party to introduce an otherwise inadmissible draft agreement into evidence for the purpose of enforcing an otherwise unenforceable mediated settlement agreement.
As the Court in Thottam held, Section 1123(c)'s requirement that all parties to a mediated settlement agreement "expressly agree in writing . . . to its disclosure," may be satisfied by terms contained in a writing other than the alleged settlement agreement itself, including a writing executed before a settlement agreement has purportedly been entered into. Because the "draft agreement" at issue in Thottam did not contain 1123's "magic" enforcement language and because the term sheet drawn up during the mediation was not sufficiently certain to enforce in any event, one party to the subject probate proceeding objected to its introduction into evidence and to the admission of testimony concerning otherwise confidential statements made during the mediation.
Had there been no confidentiality agreement, the issue would have been controlled by Evidence Code sections 1115 et seq.; the "agreement" would have been excluded from evidence as non-compliant with section 1123; and, no evidence of statements made during the mediation would have been admitted into evidence.
Here's the danger of drafting your own confidentiality agreements in an attempt to expand the scope of mediation confidentiality.
According to the appellate court opinion, because the parties expanded the scope of confidentiality beyond that provided by the statute, the exception to the protection ("except as may be necessary to enforce any agreements from the Meeting") was broader than the enforcement exception contained in section 1123. As one blogger cogently put it at the time, "the big print giveth and the small print taketh away."
I think it's safe to say that this result was pretty much completely unpredictable and that it was within the standard of care for counsel to expand the protections contained in section 1119 (for an example of the problems created by its relatively narrow confines, see mediator Debra Healy's comments and my response about the scope of mediation confidentiality in an earlier post in this series).
Post-Thottam, however, counsel must be extremely careful in drafting confidentiality agreements lest they inadvertently take away the protections the legislature created and the Supreme Court has so assiduously enforced.
In short, don't get fancy. Just stick with the language of section 1119