How strong is mediation confidentiality in California?

California has the strongest mediation confidentiality protection of any state in the country, codified in Evidence Code §§1115–1128. All mediation communications — oral, written, and nonverbal — are absolutely privileged and inadmissible in any subsequent civil proceeding. The privilege is held by the parties, the mediator, and any other participants. Unlike most states, California's confidentiality statute has no public policy exception — even evidence of fraud, duress, or attorney malpractice discovered during mediation cannot be introduced in court. The California Supreme Court has repeatedly upheld this absolute privilege, most notably in Cassel v. Superior Court (2011), where the Court held that a client could not introduce evidence of his attorney's advice during mediation to support a malpractice claim. The only statutory exceptions are: a written settlement agreement signed by the parties (which is admissible to prove the agreement); communications that are otherwise admissible or discoverable outside of mediation; and communications in a mediator misconduct proceeding. Practitioners should be aware that the absolute privilege means that a party who discovers fraud during mediation cannot use mediation communications to prove the fraud in court — this is a significant limitation that parties should understand before entering mediation.