N.J. Stat. § 43:16A-46
Any employee of any county or municipality which has adopted, or shall adopt, the State Employees' Retirement System existing under the provisions of chapter fourteen of Title 43 of the Revised Statutes, pursuant to the provisions of chapter fifteen of said Title, and has thereafter adopted, or shall adopt, the Police and Firemen's Retirement System of New Jersey created by the provisions of "An act for the establishment of a police and firemen's retirement system for the police and firemen of a municipality, county or political subdivision thereof," approved April twenty-third, one thousand nine hundred and forty-four, being chapter two hundred fifty-five of the laws of one thousand nine hundred and forty-four, by referendum, who is a policeman or fireman, as defined in said chapter two hundred fifty-five of the laws of one thousand nine hundred and forty-four, and who would be eligible to membership in the Police and Firemen's Retirement System of New Jersey but for the fact that he is a member of the State Employees' Retirement System shall, within thirty days after the effective date of this act, or when said chapter two hundred fifty-five of the laws of one thousand nine hundred and forty-four becomes effective in such county or municipality, as the case may be, be transferred to membership in the Police and Firemen's Retirement System of New Jersey created thereby.
N.J.S. § 43:16A-46