The prosecutor has to prove that the defendant operated a motor vehicle while “under the influence” of either an intoxicating liquor, a narcotic, or a hallucinogenic or habit producing drug. The proofs presented at trial may include evidence that the defendant was under the influence of one or more of these substances. The key issue in any DWI case is that the prosecutor must prove that the defendant was “under the influence.” The concept of being under the influence of either alcohol or drugs requires a “substantial deterioration or diminution of the mental faculties or physical capabilities” of the defendant. See, State v. Tamburro, 68 N.J. 414 (1975). Unlike proof of intoxication which can normally be the subject of the police officer’s opinion, proof of intoxication by drugs should normally be supported by expert testimony. See, State v. Bealor, 187 N.J. 574 (2006). To prove that a defendant operated a motor vehicle under the influence of marijuana, the prosecutor must prove that the CDS altered the defendant’s “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).
There are two modes of proof in a “under the influence” case for CDS. In the majority of cases, expert testimony from the police officer is given. In most cases, the police officers have the knowledge, and experience and training to qualify as experts under N.J.R.E. 702 in the field of discerning the effects of marijuana on human beings. In other cases, the prosecutor will have a trained DRE expert, who will give expert testimony that the defendant was driving “under the influence.” Meanwhile, in some cases, the prosecutors can simply try their “under the influence case” without an expert witness, and simply submit all of the available and admissible evidence to the judge. The Municipal Court Judge is free to consider the evidence related to the defendant’s conduct, the results of the scientific tests, as well as the direct and circumstantial evidence in deciding if the defendant operated a motor vehicle under the influence of CDS or marijuana.