The working definition of “under the influence of alcohol” as related by the case law has not changed much in the past 100 years. In State v. Emery, the New Jersey Supreme Court quoted with approval a definition that dated back to at least 1917. The court held “N.J.S.A. 39:4-50 penalizes a person who drives while under the influence of intoxicating liquor. Although prosecutions pursuant to these provisions are commonly and colloquially termed ‘drunken driving cases’, it is settled that the statute does not require as a prerequisite to conviction that the accused be absolutely drunk, in the sense of being sodden with alcohol. It is sufficient if the presumed offender has imbibed to the extent that his physical coordination or mental faculties are deleteriously affected.” State v. Emery, 27 N.J. 348 (1958).
So, at one extreme, it is not necessary that the defendant be intoxicated in the sense of being sodden with alcohol in order to be under the influence. At the other extreme, the condition of being under the influence must mean something more than having partaken of a single drink, even though physiologically, the smallest amount of alcohol has some slight effect or influence on the drinker. Considering these issues, it appears that the Legislature intended to strike a balance between these two extremes when using the term “under the influence”. The concept of being “under the influence of alcohol” is a general condition as a result of which a motor vehicle operator is so affected in judgment and control that it is improper for him to drive. Notice that the standard is improper, not unsafe, although proof of erratic driving is generally admissible as evidence of being under the influence. The proper standard of proof is proof of an impairment of either mental faculties or physical coordination.