Police and prosecutors can use blood alcohol content (BAC) evidence to prove that a defendant charged with driving while intoxicated (DWI) in New Jersey was under the influence of alcohol. State law presumes that a person was too impaired to drive safely if their BAC was 0.08 percent or higher. Evidence of BAC at or above this “legal limit” does not automatically mean, however, that the state has met its burden of proving guilt. When police are not able to conduct breath testing for BAC, such as when a driver suspected of DWI must go to the hospital after an accident, they might test a sample of the person’s blood instead. Blood testing presents different challenges for police, and opportunities for defendants to dispute the evidence against them.
Breath vs. Blood Testing
The New Jersey DWI statute uses very broad language to define the offense and state what kind of evidence the state may use to prove that a person was “under the influence of” alcohol. State and federal courts have filled in many details regarding the collection of breath, blood, or urine samples to test for BAC. Police throughout New Jersey use a device called the Alcotest to test breath samples at police stations. The device analyzes the breath sample and reports results in a few moments.
A medical professional must draw a blood sample for BAC testing. This usually occurs at a hospital. The sample must then be transported to a laboratory. Prosecutors must show a clear chain of custody for the sample, and they must be able to establish that no contamination occurred at any point.