Cal. GOV § 11415.60

(a) An agency may formulate and issue a decision by settlement, pursuant to an agreement of the parties, without conducting an adjudicative proceeding. Subject to subdivision (c), the settlement may be on any terms the parties determine are appropriate. Notwithstanding any other provision of law, no evidence of an offer of compromise or settlement made in settlement negotiations is admissible in an adjudicative proceeding or civil action, whether as affirmative evidence, by way of impeachment, or for any other purpose, and no evidence of conduct or statements made in settlement negotiations is admissible to prove liability for any loss or damage except to the extent provided in Section 1152 of the Evidence Code. Nothing in this subdivision makes inadmissible any public document created by a public agency.

(b) A settlement may be made before or after issuance of an agency pleading, except that in an adjudicative proceeding to determine whether an occupational license should be revoked, suspended, limited, or conditioned, a settlement may not be made before issuance of the agency pleading. A settlement may be made before, during, or after the hearing.

(c) A settlement is subject to any necessary agency approval. An agency head may delegate the power to approve a settlement. The terms of a settlement may not be contrary to statute or regulation, except that the settlement may include sanctions the agency would otherwise lack power to impose.