N.J. Stat. § 5:15-4
A participant or a spectator shall not engage in, attempt to engage in, or interfere with, an equine animal activity if he is knowingly under the influence of any alcoholic beverage as defined in R.S. 33:1-1 or under the influence of any prescription, legend drug or controlled dangerous substance as is defined in P.L. 1970, c.226 (C.24:21-1 et seq.), or any other substance that affects the individual's ability to safely engage in the equine animal activity and abide by the posted and stated instructions. The operator may prevent a participant or a spectator who is perceptibly or apparently under the influence of drugs or alcohol, from engaging in, or interfering with, an equine animal activity or being in an equestrian area. An operator who prevents a participant or a spectator from engaging in, or interfering with, an equine animal activity, or being in an equestrian area in accordance with this section shall not be criminally or civilly liable in any manner or to any extent whatsoever if the operator has a reasonable basis for believing that the participant or spectator is under the influence of drugs or alcohol.
N.J.S. § 5:15-4