The Way Blood Samples Are Obtained and Tested Can Make a Difference in New Jersey DWI Cases

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.

Collection of Breath or Blood Samples

New Jersey police can collect breath samples from anyone suspected of DWI thanks to the state’s implied consent statute. For blood samples, they must obtain a warrant unless they can show “exigent circumstances” making it impractical to get a warrant first. Until several decades ago, doctor-patient confidentiality prevented police from using blood samples collected for medical purposes after a car accident. For example, a Law Division judge granted a DWI defendant’s motion to suppress blood test results in 1974, while also questioning “the sanctity of an emergency room relationship between two persons unknown to each other five minutes before.” The New Jersey Supreme Court, however, overturned this holding ten years later.

Types of Blood Samples

Hospital laboratories and forensic laboratories conduct blood tests for different purposes. While hospital labs generally seek to diagnose illnesses and other conditions, forensic labs seek evidence for use in prosecutions. This can make a difference when the state tries to use BAC test results obtained from a hospital lab.

Forensic labs typically test “whole blood,” meaning all of the components of blood as they come out of someone’s veins. Hospitals often use “blood serum,” which has had the red blood cells and other components removed.

BAC is expressed as a percentage of the total volume of a sample. Research has shown that ethanol, the main intoxicating ingredient in alcoholic beverages, appears in greater percentages in tests of blood serum instead of whole blood. Since the legal standard for BAC is based on whole blood, hospital labs are supposed to account for this when reporting their results. If they do not account for the difference, the BAC could appear much higher than it actually was.

If you are facing DWI charges in a New Jersey municipal court, DWI lawyer Evan Levow can help you understand your rights and options. Please contact us online or at (877) 593-1717 today to schedule a free and confidential consultation.