A little clarification on the NJ tint laws:
You can tint any window to the rear of the drivers as dark as you want so long as you have both side mirrors in place.
You cannot tint either front side window to any degree without a medical exemption (see below).
The windshield can be tinted only down to the AS1 line (about 6" down from the top). The line is usually visible on the passenger side of the windshield. A medical exemption can also waive this.
Medical exemption can be granted only by DMV is West Trenton after meeting several stringent criteria. A doctors note is NOT a medical exemption. After meeting all the criteria, DMV will issue you a card with the allowable tint percentage for each window. Technically there are only 5 or 6 companies in the entire State that are allowed to install medical exemption tint.
Just so everyone understands, the NJ tint law is covered under NJSA 39:3-75 but other statutes can be applied (ex. 39:3-77, unapproved equipment, etc.). In addition, if you look up the law it will state "...rules promulgated by the Director of DMV..." Those rules are stated elsewhere in the administrative code. Thats where the specifics of what is allowed is written.
Another note; if you go through inspection with tinted windows YOU WILL PASS. Effective last year or so, DMV inspection is only for emissions. You will technically pass with plywood over the windows and three wheels. That doesnt mean that you cant, or wont, get a ticket.
A lot of cops see window tint as a way to get away with using a cell phone while driving. The ticket is actually written a lot for that reason.
Last thing that I know will annoy you more than anything else: Police cars are specifically exempt from the window tint law. Let the complaining begin.