Firemen's, policemen’s or peace officers’ benefit and relief associations now existing, or which may be formed hereafter for the purpose of aiding their members or dependents of their members in case of sickness, accident, distress, or death, shall be subject to the provisions of this chapter. While such an association operates strictly in accordance with this chapter, it shall not be subject to any other provision of this code nor to any law of this State relating to insurance, whether now existing or hereafter enacted, except when expressly designated therein.