California Code, Government Code - GOV § 75563

(a) Shall be presumed not to be disabled and this presumption is a presumption affecting the burden of proof.

(b) Shall, in a disability retirement proceeding before the commission, be subject to the standard of proof of clear and convincing evidence sufficient to sustain a claim to a reasonable certainty.

(c) Shall support the application with written statements described in subdivision (c) of Section 75560.1 from each of at least two physicians or two psychiatrists.