Here is some important precedent regarding proof of intoxication for DWI cases in New Jersey:
State v. Johnson, 42 N.J. 146 (1964)
The court held that proof of intoxication may be established either through breath test or other toxicology tests, or by other evidence such as the driver’s own admissions or his performance of psycho-physical tests.
Romano v. Kimmelman, 96 N.J. 66 (1984)
The NJ Supreme Court established the reliability and admissibility of breathalyzer test results. The court held that (1) manufacturers’ breathalyzer models “900” and “900A” are scientifically reliable for purpose of determining content of blood alcohol, with narrow qualification as to admissibility of test results relating to possible effects of radio frequency interference; (2) results of administration of model “900” can be received in evidence without further proof establishing any additional conditions for admissibility relating to effects of radio frequency interference, provided that hand-held transmitters are banned from area in close proximity to breathalyzer instrument; (3) model “900A” results may be admitted in evidence and form basis of driving under influence conviction either if breathalyzer result consists of two tests or readings within tolerance of 0.10 percent of each other, breathalyzer instrument has been found not to be radio frequency interference-sensitive, or if sensitive, it is shown that in administration of instrument, instrument was protected from transmitters and radio frequency; and (4) new trial on newly discovered evidence may be brought only when conviction based upon such breathalyzer results could possibly have been affected by radio frequency interference.
State v. Maida, 332 N.J. Super 564 (2000)
The court held (1) that the coordinator’s certificate was sufficient to carry the burden of proof as to accuracy of breath test machine and (2) the Horizontal Gaze Nystagmus (HGN) test was sufficiently reliable to be admitted as scientific evidence of intoxication in a criminal trial.
State v. Cryan, 363 N.J. Super 442 (2003)
The court held under the influence means a condition which so affects the judgment or control of the motor vehicle operator as to make it improper for him to drive on the highway. In this case bloodshot eyes, a strong odor of alcohol on his breath, and hostile and erratic behavior were sufficient to establish driving while intoxicated.
State v. Slinger, 281 N.J. Super 538 (1995)
The court held that proof of intoxication can be shown independent of the breathalyzer results where, as here, defendant’s erratic driving, his physical appearance, demeanor, and speech, as well as the smell of alcohol on his breath were sufficient reliable indicia to establish driving while intoxicated.