Mo. Rev. Stat. § 375.426
The director shall have the power to make such rules and regulations as may be necessary for the execution of the functions vested in him by sections 375.422 to 375.426, and may for such purpose classify such insurance companies, securities, and other persons or matters within his jurisdiction. All such rules and regulations shall conform to, and be subject to, the provisions of chapter 536 as now constituted or hereafter amended. No provision of sections 375.422, 375.423 and 375.424, imposing any liability shall apply to any act done or omitted in good faith in conformity with any rule or regulation of the director, notwithstanding that such rule or regulation may, after such act or omission, be amended or rescinded or determined by judicial or other authority to be invalid for any reason.
§ 375.426, RSMo