New Jersey State law presumes that a driver who strikes to another driver from the rear bears 100 percent liability for an accident. Therefore, the onus falls on the driver who strikes from the rear to prove that he or she is not liable, which is difficult. The only firm exception to this rule is a "chain reaction", where a driver hits a car, and pushes into another.
However, if the driver in front cuts off the driver who is behind them, then the courts may shift liability. Proving this in court requires a skilled accident attorney, as the burden of the proof is on you, and not the driver of the car you hit. Drive safely, drive defensively, and feel free to contact us for our free book on what to do if you're ever in an accident at njaccidentbook.com