Welfare and Institutions Code § 21003

(a) An adult with a disability may choose to enter into a supported decisionmaking agreement with one or more chosen supporters. Support may include, but is not limited to, helping the adult with a disability obtain and understand information related to a life decision, communicating the decision to others, and assisting the individual to ensure their preferences and decisions are honored.

(b) An adult with a disability’s signing of a supported decisionmaking agreement does not preclude the adult with the disability from acting independently of a supported decisionmaking agreement and shall not be used by a court or other entity as evidence of incapacity. This subdivision does not limit the admissibility of evidence pursuant to Section 28 of Article 1 of the California Constitution.