N.J. Stat. § 11A:6-12
An appointing authority may grant an unpaid leave of absence to any employee elected or appointed as an officer or representative of a local, county or State labor organization which represents, or is affiliated with a local, county or State labor organization which represents, public employees.
An appointing authority may grant a paid leave of absence to any such employee, (1) provided the employer is reimbursed in advance for compensation and benefit costs including retirement system contributions and health benefit premiums or periodic charges paid during the period of absence, or (2) in accordance with the terms of a collective bargaining agreement.
The maximum period for such paid and unpaid leaves shall be a subject of negotiation between the employer and union.
N.J.S. § 11A:6-12