N.J. Stat. Ann. § 40:41A-130

The board of freeholders of any county adopting one of the plans of government set forth in this act may by resolution apply to the New Jersey Civil Service Commission for permission to administer the merit system through a county department of civil service. Such administration shall include classification, recruitment, examination, establishment of eligibility lists, grievances, compensation, and other conditions of employment, all to be performed under the general supervision of the New Jersey Department of Civil Service, and in addition such other functions as the State Department may authorize or approve. Any civil service system administered by a county shall be limited in application to county employees and positions, and may not extend to cover employees and positions in municipalities within that county.