California Code, Civil Code - CIV § 40

(a) Subject to Section 1871 of the Probate Code, and subject to Part 1 (commencing with Section 5000) of Division 5 of the Welfare and Institutions Code, after his or her incapacity has been judicially determined a person of unsound mind can make no conveyance or other contract, nor delegate any power or waive any right, until his or her restoration to capacity.

(b) Subject to Sections 1873 to 1876, inclusive, of the Probate Code, the establishment of a conservatorship under Division 4 (commencing with Section 1400) of the Probate Code is a judicial determination of the incapacity of the conservatee for the purposes of this section.