California Mediation Privilege: Limits, Waivers, and Malpractice Risk

California’s mediation privilege, codified at Evidence Code Sections 1115 through 1129, makes almost everything said, written, or exchanged in connection with a mediation confidential and inadmissible in any noncriminal proceeding. It is one of the broadest confidentiality rules in the country, and California courts have refused to create exceptions the Legislature did not write. That reach protects candid negotiation, and it also creates traps: a settlement that isn’t enforceable, a malpractice claim you can’t prove, a sanctions motion you can’t support.

What the Privilege Covers

Section 1119 does the core work. It bars three things from admission or discovery: anything said or admitted during a mediation or mediation consultation, any writing prepared for or in the course of a mediation, and settlement discussions between participants.¹ “Noncriminal proceeding” is broad. It covers civil lawsuits, arbitration, and administrative hearings.

The protection reaches beyond the mediation room. Communications made “for the purpose of” or “pursuant to” a mediation are covered, and so are “mediation consultations” — conversations with a mediator about starting, resuming, or retaining the mediator.¹ Pre-mediation briefs, scheduling emails, and follow-up exchanges can all fall inside.

In Cassel v. Superior Court (2011), the California Supreme Court held that even private conversations between a client and his own lawyers during mediation are protected, because those communications were made for the purpose of and pursuant to the mediation.² The privilege does not sort by who is in the conversation. It sorts by the conversation’s connection to the mediation.

What Stays Admissible

Section 1120 keeps the privilege from swallowing everything a party touches during a mediation. Evidence that was already admissible or discoverable outside the mediation stays that way. A contract, a photograph, a financial statement — bringing it to mediation does not immunize it from later discovery.³

Section 1120 also lists items the mediation chapter never restricts:

The agreement to mediate itself.
Procedural agreements, such as not to take a default or to extend litigation deadlines.
The bare fact that a particular person served or was contacted about serving as a mediator.
Declarations of disclosure required in dissolution cases by Family Code Sections 2104 and 2105.³

The last item matters in divorce. Spouses must exchange mandatory financial disclosures, and the mediation privilege cannot be used to hide them from the court or the other spouse.

Making a Mediated Settlement Enforceable

This is where people lose cases they thought they had won. A written settlement reached in mediation is, by default, a confidential mediation writing. Section 1123 pulls it out of the privilege only if the settling parties sign it and it meets one of these conditions:

It states that it is “admissible or subject to disclosure,” or words to that effect.
It states that it is “enforceable or binding,” or words to that effect.
All parties expressly agree in writing, or orally under Section 1118, to disclose it.
It is used to show fraud, duress, or illegality relevant to a dispute.⁴

A term sheet that omits words like “binding” or “enforceable” may not be admissible to prove the deal existed. Including that language is the mechanism that takes the agreement outside the privilege.

Oral agreements follow a parallel path under Section 1124. They generally must be placed on the record before the court or a designated authority under Section 1118. An oral side deal between the parties alone will not survive a confidentiality challenge.¹

Waiving Confidentiality

Section 1122 allows waiver, but on strict terms. A mediation communication or writing loses its protection only if:

Every person who participated in the mediation, including the mediator, expressly agrees to disclosure, in writing or orally under Section 1118.⁵
The writing was prepared by or on behalf of fewer than all participants, those participants agree in writing, and the writing does not reveal anything said, done, or admitted during the mediation.
The communication relates to whether an attorney complied with the Section 1129 disclosure requirement, and it does not reveal mediation content.

The unanimity requirement is where most waiver attempts fail. One party cannot unilaterally disclose what happened, even to support a legitimate claim, and the mediator’s refusal alone defeats waiver. Parties who want the option to use mediation communications later should negotiate a written waiver before the session. Obtaining consent after a mediation collapses is much harder.

When the Mediation Ends

The privilege attaches to communications made “in the course of” or “pursuant to” the mediation, so knowing when it ends matters. Section 1125 identifies five terminating events:

All parties sign a written agreement fully resolving the dispute.
All parties present an oral agreement to the court under Section 1118.
The mediator provides written, signed notice of termination.
Any party gives written notice of termination to the mediator and all other participants.
Ten calendar days pass with no communication between the mediator and any party about the dispute, or a shorter period the parties agreed to.¹

If the parties resolve only some issues, the mediation ends as to those issues and can continue on the rest. The ten-day silence rule catches mediations that simply fizzle out.

What the Mediator Can Tell the Court

Section 1121 flatly prohibits anyone from submitting to a court any report, assessment, evaluation, recommendation, or finding by the mediator about the mediation. The court cannot consider such materials. The only allowance is a report required by court rule or law that says nothing more than whether the parties reached an agreement.¹ Parties can agree in writing or on the record to expand the mediator’s report, but absent that agreement the mediator’s report is binary: agreement or none.

The California Supreme Court applied this rule strictly in Foxgate Homeowners’ Association v. Bramalea California, Inc. (2001), holding that a mediator could not report a party’s obstructive behavior and that the trial court could not use such a report to impose sanctions. The court said “there are no exceptions to the confidentiality of mediation communications or to the statutory limits on the content of mediator’s reports.”⁶ If you believe the other side mediated in bad faith, you can say so — you cannot prove it with anything the mediator saw or heard.

No Crime-Fraud Exception

Unlike the attorney-client privilege, California’s mediation confidentiality statutes contain no crime-fraud exception. This is one of the most commonly misunderstood parts of the law. The Uniform Mediation Act includes such an exception, but California has not adopted the UMA.

California courts have refused to fill the gap. Foxgate rejected judicial exceptions generally. In Wimsatt v. Superior Court (2007), the Court of Appeal struck down a trial court’s attempt to carve out an exception for perjury and inconsistent statements, holding that “if an exception is to be made for legal misconduct, it is for the Legislature to do, and not the courts.”⁷

Two narrow safety valves exist. Section 1120 keeps independently existing evidence of wrongdoing admissible even if someone brought it up in mediation. And Sections 1123(d) and 1124(c) allow a mediated settlement agreement to be used as evidence when needed to show fraud, duress, or illegality. But the broader communications inside the mediation remain protected, even if one party used the process dishonestly.

The Malpractice Trap

Cassel is the reason this is such a serious problem. Michael Cassel settled business litigation in mediation and then sued his own attorneys for malpractice. The Supreme Court held that his private discussions with those lawyers during the mediation were fully privileged, and acknowledged this might “compromise petitioner’s ability to prove his claim of legal malpractice.”² If your lawyer gives you bad advice, pressures you, or misrepresents the other side’s position while a mediation is ongoing, the communications you need to prove it are locked behind the same privilege that shielded your candor.

Section 1129 gives clients a partial safeguard: attorneys must provide clients with a written disclosure explaining how mediation confidentiality affects their ability to bring a malpractice claim, and a document showing compliance with that requirement can be used in disciplinary proceedings under Section 1122(a)(3). That addresses whether the warning was given. It does not open the door to proving what happened inside the mediation.

The Penalty for Slipping Up in Court

Section 1128 gives the confidentiality rule real teeth. Any reference to a mediation during a later trial is treated as an irregularity in the proceedings under Code of Civil Procedure Section 657, which is a ground for a new trial. In any other noncriminal proceeding, a reference to mediation is grounds for vacating or modifying the decision and ordering a new hearing, if the reference “materially affected the substantial rights” of the party seeking relief.⁸ A party, attorney, or witness who lets mediation content slip into a trial risks unwinding the entire proceeding.

Family Law and Federal Court Boundaries

Custody and visitation mediation operates under its own confidentiality framework. Family Code Section 3177 says these mediation proceedings “shall be held in private and shall be confidential,” and classifies communications to the mediator as “official information” under Evidence Code Section 1040.⁹ Dependency mediation is governed by California Rules of Court Rule 5.518, which requires dependency mediators not to make “any recommendations or reports of any kind to the court, except for the terms of any agreement reached by the parties.”¹⁰ There is no general child-welfare exception to family law mediation confidentiality. The only routine carve-out is the mandatory dissolution financial disclosure noted above.

In federal court, coverage depends on the type of case. Federal Rule of Evidence 501 provides that state privilege law governs when state law supplies the rule of decision, so a diversity case applying California substantive law also applies California’s mediation privilege.¹¹ In federal question cases, federal common law controls, and there is no generally recognized federal mediation privilege, though individual districts often impose confidentiality on their court-connected mediation programs by local rule.

1
California Legislative Information. California Evidence Code – Mediation
2
Supreme Court of California. Cassel v. Superior Court
3
California Legislative Information. California Evidence Code 1120 – Mediation
4
California Legislative Information. California Evidence Code 1123 – Written Settlement Agreement
5
California Legislative Information. California Evidence Code 1122 – Disclosure of Communication or Writing
6
Justia Law. Foxgate Homeowners Assn. v. Bramalea California, Inc.
7
FindLaw. Wimsatt v. Superior Court
8
California Legislative Information. California Evidence Code 1128
9
California Legislative Information. California Family Code 3177 – Confidentiality of Mediation Proceedings
10
Judicial Branch of California. California Rules of Court Rule 5.518 – Court-Connected Child Protection/Dependency Mediation
11
Legal Information Institute. Rule 501 – Privilege in General