N.J. Stat. § 9:6-7
Any duly organized or incorporated humane society, having for one of its objects the protection of children from cruelty, may offer any agents or officers employed by such society to the mayor or other executive officer having authority to commission police officers of any municipality having a regularly organized police department, for the purpose of being commissioned to act as police officers through the limits of such municipality for the purpose of arresting all the offenders against this chapter or any of the provisions thereof, whereupon the mayor in such city shall, if such persons are proper and discreet persons, commission them to act as such police officers, with all the rights and powers appertaining thereto; but no such municipality shall be liable in any way for the salary or wages of such officers, or for any expense whatever in relation thereto, except for the detention of prisoners.
In any municipality not having a regularly organized police department, such humane society may offer similarly qualified persons to the Assignment Judge of the Superior Court for the county, whereupon such court shall, if they be fit persons, commission such persons to act as constables, with power to arrest all offenders against this chapter or any provisions thereof; but no municipality or county shall be in anywise liable for the salary or wages of any such officer, or for any expense in relation thereto, except for the detention of prisoners.
All persons thus qualified under this section shall be deemed to be constables and police officers, and the keepers of jails or lockups or station houses in any of such counties are required to receive all persons arrested by such policemen or constables.
N.J.S. § 9:6-7