N.J. Stat. § 34:15-9
Every contract of hiring made subsequent to the fourth day of July, one thousand nine hundred and eleven, shall be presumed to have been made with reference to the provisions of this article, and unless there be as a part of such contract an express statement in writing prior to any accident, either in the contract itself or by written notice from either party to the other, that the provisions of this article are not intended to apply, then it shall be presumed that the parties have accepted the provisions of this article and have agreed to be bound thereby.
Every contract of hiring made or implied or in operation before the fourth day of July, one thousand nine hundred and eleven, shall be presumed to continue subject to the provisions of this article unless either party shall prior to accident, in writing, notify the other party to such contract that the provisions of this article are not intended to apply.
N.J.S. § 34:15-9