N.J. Stat. § 39:5-20
On an appeal by the defendant in any proceeding instituted under this subtitle, the county prosecutor of the county wherein the alleged violation was committed shall represent the complainant; but where a complaint is made by a member of the State Police charging a violation of either section 39:3-40, 39:4-50 or 39:4-96 of this Title, the Attorney General, and not the prosecutor, shall represent the complainant, and where there is violation of a municipal ordinance relating to traffic regulations and the proceeding was instituted by a municipal officer, the municipal attorney shall represent the complainant. The county prosecutor, charged with the enforcement of this subtitle, may request the Attorney General to attend personally, or by such assistant or assistants as he shall designate, to aid in the prosecution of the appeal.
N.J.S. § 39:5-20