In my previous post I discussed the “under the influence of alcohol” language of the New Jersey drinking and driving statute N.J.S.A. 39:4-50. There is also important case law regarding driving while intoxicated (DWI) prosecutions for driving while under the influence of drugs. The New Jersey Supreme Court considered this issue in State v. Bealor, 187 N.J. 574 (2006). “Expert testimony remains the preferred method of proof of marijuana intoxication. We arrive at that conclusion in the knowledge that it is not too difficult a burden for the State to offer an expert opinion as to marijuana intoxication. Prosecutors in municipal courts throughout the State routinely qualify local and state police officers to testify as experts on the subject of marijuana intoxication. Expert testimony only requires that a witness be qualified ‘by knowledge, skill, experience, training, or education.’” Id. An operator of a motor vehicle is under the influence of a narcotic drug within the meaning of N.J.S.A. 39:4-50(a) if the drug produced a narcotic effect so altering his or her “normal physical coordination and mental faculties as to render such person a danger to himself, as well as to other persons on the highway.” State v. Dicarlo, 67 N.J. 321 (1975). A lay witness if sufficiently experienced and trained may testify generally as to the observable reaction of drug users and of the technique of the use. State v. Jackson, 124 N.J. Super 1.