California Code, Insurance Code - INS § 10384

No insurer issuing or providing any policy of disability insurance covering hospital, medical, or surgical expenses shall engage in the practice of postclaims underwriting. For purposes of this section, “postclaims underwriting” means the rescinding, canceling, or limiting of a policy or certificate due to the insurer's failure to complete medical underwriting and resolve all reasonable questions arising from written information submitted on or with an application before issuing the policy or certificate.