N.J. Stat. § 48:3-32
Every public utility operating any street railway, traction railway or autobus shall transport, without the collection of fares from them, uniformed public officers while engaged in the performance of their public duties, and all police officers of whatever grade or rank acting as detectives, county detectives or detectives connected with the office of any prosecutor of the pleas in any county while engaged in the performance of their public duties, whose duties require police duty to be performed without uniform.
For such transportation an amount equal to the lawful fares shall be credited on account of any franchise tax or charges in the nature thereof payable or apportioned by law or ordinance to any municipality wherein the transportation takes place.
N.J.S. § 48:3-32