Cal. Prob. Code § 6100.5

(a) An individual is not mentally competent to make a will if, at the time of making the will, either of the following is true: (1) The individual does not have sufficient mental capacity to be able to do any of the following: (A) Understand the nature of the testamentary act. (B) Understand and recollect the nature and situation of the individual’s property. (C) Remember and understand the individual’s relations to living descendants, spouse, and parents, and those whose interests are affected by the will. (2) The individual suffers from a mental health disorder with symptoms including delusions or hallucinations, which delusions or hallucinations result in the individual’s devising property in a way that, except for the existence of the delusions or hallucinations, the individual would not have done.

(b) This section does not supersede existing law relating to the admissibility of evidence to prove the existence of mental incompetence or mental health disorders.

(c) Notwithstanding subdivision (a), a conservator may make a will on behalf of a conservatee if the conservator has been authorized to do so by a court order pursuant to Section 2580.