N.J. Stat. Ann. § 4:15-4

The directors of an association, or a majority of them, may appoint from time to time, as many fit persons as they may deem proper, as special police officers. Each such officer, before entering upon his duties, shall take and subscribe an oath that he will well and truly serve the State, and will perform all his duties to the best of his knowledge and ability. The oath shall be filed forthwith in the office of the county clerk who shall indorse thereon the date of filing and shall be paid the sum of twenty cents ($0.20) for each oath so filed.