Unless consented to by the parties, evidence of anything said or of admissions made, or documents prepared for the purpose of mediation is not admissible in evidence in any civil action. Civil Code §1354(g),(h)
The California Supreme Court in Foxgate HOA v. Bramalea
(2001) held that "confidentiality is essential to effective mediation. In addition, Rojas v. Superior Court (2004) held that writings made for, during and pursuant to mediation are not discoverable. In 2011, the California Supreme Court in a unanimous decision and confirmed the doctrine of mediation confidentiality. In Cassel v. Superior Court (2011) 51 Cal.4th 113.
However, confidentiality is not conferred upon facts or a document just because either is referred to or used at mediation. Documents which would otherwise be discoverable cannot be shielded by mediation.