N.J. Ct. R. 4:37-1

(a) By Plaintiff; By Stipulation. Subject to the provisions of R. 4:32-2(e) (class actions), R. 4:53-1 (receivership actions) and R. 4:60-18 (attachment actions), an action may be dismissed by the plaintiff without court order by filing a notice of dismissal at any time before service by the adverse party of an answer or of a motion for summary judgment, whichever first occurs; or by filing a stipulation of dismissal specifying the claim or claims being dismissed, signed by all parties who have appeared in the action. Unless otherwise stated in the notice or stipulation, the dismissal is without prejudice.

(b) By Order of Court. Except as provided by paragraph (a) hereof, an action shall be dismissed at the plaintiff's instance only by leave of court and upon such terms and conditions as the court deems appropriate. If a counterclaim has been filed and served by a defendant prior to being served with plaintiff's motion to dismiss, the action shall not be dismissed against the defendant's objection unless the counterclaim can remain pending for independent adjudication by the court. Unless otherwise specified in the order, a dismissal under this paragraph is without prejudice.