N.J. Admin. Code § 16:87-2.1
The use of a rail passenger service by a person shall constitute an agreement by the person to pay the prescribed fare for the service. A person who has paid the prescribed fare for a rail passenger service and who has been issued proof of payment therefor shall retain that proof of payment while in a pre-paid fare area or in or on designated rail passenger facilities or vehicles. In addition, single use tickets and transfers must be properly validated in order to constitute proof of payment. Validated tickets are good until the expiration of the time imprinted on them by the validator. Single use tickets which have not been validated, have an improper date, or are time expired do not constitute proof of payment.
N.J. Admin. Code § 16:87-2.1