[§431M-2] Policy coverage. All individual and group accident and sickness insurance policies issued in this State, individual or group hospital or medical service plan contracts, and nonprofit mutual benefit association and health maintenance organization health plan contracts shall include within their hospital and medical coverage the benefits of alcohol dependence, drug dependence, and mental illness treatment services provided in section 431M-4 except that this section shall not apply to insurance policies that are issued solely for single diseases, or otherwise limited, specialized coverage. [L 1988, c 202, pt of §1]