N.J. Stat. § 40:20-26
The terms of office of all officers then holding office under appointment by the board of chosen freeholders existing in any county at the time of reorganization thereof under sections 40:20-20 to 40:20-35 of this title in such county, shall not be affected thereby but the officers then holding office shall continue in office during the terms for which they were originally appointed or elected and until their successors shall have been appointed or elected and shall have duly qualified. Thereafter all offices to be filled by the board of chosen freeholders shall be for the term of three years.
Nothing in this section contained shall apply to or affect any honorably discharged soldier, sailor or marine of the United States, or any honorably discharged member of the American Merchant Marine who served during World War II and is declared by the United States Department of Defense to be eligible for federal veterans' benefits, or the widow of such soldier, sailor, marine or member of the American Merchant Marine, in office at the time of the adoption of said sections 40:20-20 to 40:20-35 by any county. All such persons shall continue and remain in their respective offices during good behavior, and shall be removed only for cause.
Nothing in this section contained shall apply to or affect any officer coming within the provisions of section 51:1-53 of the title Standards, Weights, Measures and Containers.
N.J.S. § 40:20-26