N.J. Stat. Ann. § 52:14-2

Whenever in carrying out the work of a department, the services of any expert or the use of any special apparatus shall be desired or any work needs to be done for which the department is not equipped, the head thereof may request the assistance of any other department which may have the needed experts or apparatus. The head of the department so called upon may co-operate in meeting said need in so far as it can be done without detriment to the work of his own department. The heads of the departments concerned shall agree as to a proper charge, if any, to be made for such services or material or use of apparatus.