N.J. Stat. § 39:3-33
The owner of an automobile which is driven on the public highways of this State shall display not less than 12 inches nor more than 48 inches from the ground in a horizontal position, and in such a way as not to swing, a registration plate or plates to be furnished by the commission; provided, that if two registration plates are issued they shall be displayed on the front and rear of the vehicle; and provided, further, that if only one registration plate is issued it shall be displayed on the rear of the vehicle; and provided, further, that the rear registration plate may be displayed more than 48 inches from the ground on tank trucks, trailers, and other commercial vehicles carrying inflammable liquids and on sanitation vehicles which are used to collect, transport, and dispose of garbage, solid wastes, and refuse. Motorcycles shall also display a registration plate or plates; provided, that if two registration plates are issued they shall be displayed on the front and rear of the motorcycle; and provided, further, that if only one registration plate is issued it shall be displayed on the rear of the motorcycle.
The registration plate shall contain the number of the registration certificate of the vehicle and shall be of such design and material as prescribed pursuant to section 2 of P.L.1989, c.202 (C.39:3-33.9). All registration plates shall be kept clear and distinct and free from grease, dust, or other blurring matter, so as to be plainly visible at all times of the day and night.
A person shall not drive a motor vehicle which has a registration plate frame or holder that conceals or otherwise obscures the name of the State or the registration number furnished by the commission imprinted upon the vehicle's registration plate, or any part of any insert which the commission, as hereinafter provided, issues to be inserted in and attached to that registration plate, or that conceals or otherwise obscures the name of the State, the registration number, or the expiration date on any temporary registration certificate or temporary registration plate issued by the commission. It shall not be a violation of this section and therefore not a basis for a lawful stop if part of the name of the State or the registration number imprinted on a vehicle's registration plate, or part of an insert issued by the commission inserted in or attached to the registration plate, or part of the name of the State, the registration number, or the expiration date on a temporary registration certificate or temporary registration plate is concealed or otherwise obscured in a way such that the information to which this provision applies can still reasonably be identified or discerned. The Attorney General shall issue such guidance as the Attorney General deems necessary for law enforcement officers to properly interpret and enforce the provisions of this section.
The chief administrator is authorized and empowered to issue registration plate inserts, to be inserted in and attached to the registration plates described herein. They may be issued in the place of new registration plates; and inscribed thereon, in numerals, shall be the year in which registration of the vehicle has been granted.
No person shall drive a motor vehicle the owner of which has not complied with the provisions of this subtitle concerning the proper registration and identification thereof, nor drive a motor vehicle which displays a fictitious number, or a number other than that designated for the motor vehicle in its registration certificate. During the period of time between the application for motor vehicle registration and the receipt of registration plates from the commission, no person shall affix a plate for the purpose of advertisement in the position on a motor vehicle normally reserved for the display of the registration plates required by this section if the plate is designed with a combination of letters, numbers, colors, or words to resemble the registration plates required by this section.
A person convicted of displaying a fictitious number, as prohibited herein, shall be subject to a fine not exceeding $500 or imprisonment in the county jail for not more than 60 days.
A person violating any other provision of this section shall be subject to a fine not exceeding $100. In default of the payment thereof, there shall be imposed an imprisonment in the county jail for a period not exceeding 10 days. A person convicted of a second offense of the same violation may be fined in double the amount herein prescribed for the first offense and may, in default of the payment thereof, be punished by imprisonment in the county jail for a period not exceeding 20 days. These penalties shall not apply to the display of a fictitious number.
N.J.S. § 39:3-33