Insurance Code (usually included in commercial codals)
Section 92. If the policy requires, by way of preliminary proof of loss, the certificate or testimony of a person other than the insured, it is sufficient for the insured to use reasonable diligence to procure it, and in case of the refusal of such person to give it, then to furnish reasonable evidence to the insurer that such refusal was not induced by any just grounds of disbelief in the facts necessary to be certified or testified.