N.J. Stat. § 18A:17-42
The legislature finds that the safety and welfare of the public school students of this state while attending sessions of the public schools is a matter of prime concern to the citizens of this state; that, in several isolated instances throughout this state, unlawful intruders into the public schools have subjected public school students and their teachers to physical and verbal attacks during sessions of the public schools and on the property of said public schools; that such attacks might have been prevented, and similar attacks will be prevented, if public school law enforcement officers are stationed in said schools; and that state aid to local boards is necessary to help such boards bear the cost of employing and stationing public school law enforcement officers.
N.J.S. § 18A:17-42