California Code, Welfare and Institutions Code - WIC § 21004

(a) Notwithstanding any other provision of this division, an adult with a disability is entitled to have present one or more other adults, including supporters, in any meeting or discussion, or to participate in any written communication, including, but not limited to, individual planning meetings required by state or federal law, service and care planning meetings, discharge planning meetings, meetings with health care providers and individuals who provide residential services or long-term services and supports, and communications with a bank, financial institution, or financial planner.

(b) An adult with a disability may indicate that they wish to have one or more adults attend a meeting or discussion or participate in any written communication through oral statement, gesture, or any augmentative or alternative communication method used by the adult with a disability.

(c) A third party may only refuse the presence of one of more adults, including supporters, if the third party reasonably believes that there is fraud, coercion, abuse, or other action by the individuals requested to be included that the third party is required to report pursuant to the Elder Abuse and Dependent Adult Civil Protection Act (Chapter 11 (commencing with Section 15600) of Part 3 of Division 9).

(d) The Legislature finds and declares that this section is declaratory of existing law.