In order to prove guilt in driving while intoxicated (DWI) cases in New Jersey, law enforcement must show that a defendant was under the influence of either alcohol or certain types of drugs. State law allows them to use chemical tests that allegedly show the presence of alcohol or drugs. Chemical testing for alcohol has an extensive body of law addressing how police must collect and test samples of a DWI suspect’s breath. For other drugs, they must use samples of blood or urine. This type of testing can be much less certain, both scientifically and legally. Urine testing, in particular, has significant reliability issues. If the state tries to introduce results from urine tests, DWI attorneys must carefully examine the evidence to look for errors.
New Jersey has used chemical testing in DWI and DUID cases for decades. In 1964, the New Jersey Supreme Court held that “[a]lcoholic content in the blood furnishes a scientific measure of the extent of the influence of liquor upon the person.” It went on to state that “chemical analysis of the blood itself, urine, breath and other bodily substances is a scientifically accurate method of ascertaining that content.”
State law currently defines the offense of DWI in two ways: “operat[ing] a motor vehicle” either (1) while impaired by an “intoxicating liquor, narcotic, hallucinogenic or habit-producing drug;” or (2) “with a blood alcohol concentration [BAC] of 0.08% or more by weight of alcohol in the defendant’s blood.” BAC above the “legal limit” of 0.08% creates a presumption that the defendant is legally impaired by alcohol. The state’s implied consent statute makes breath testing mandatory in DWI investigations.