California Code, Government Code - GOV § 946.4

(a) Where provision is made by or pursuant to law that no suit may be brought against a public agency as defined in Section 53050 unless and until a claim is presented to the agency, the failure to present a claim does not constitute a bar or defense to the maintenance of a suit against the public agency if, during the 70 days immediately following the accrual of the cause of action, either of the following apply:

(b) On any question of fact arising within the scope of paragraphs (1) and (2) of subdivision (a), the burden of proof is upon the public agency.

(c) This section is inapplicable where the presentation of a claim is required by a claims procedure established by agreement made pursuant to Section 930.2 unless the procedure so prescribed requires that the claim be presented to the governing body of the public agency or to a person listed in Section 53051.