People think a DWI case comes down to one number on a breath machine. It doesn’t. A New Jersey DWI prosecution is built step by step — the stop, the roadside tests, the observation period, the breath test — and the State has to follow specific rules at every one of them. Each step is also where a defense can start.
Here’s what actually happens, in order, and what matters legally at each stage.
1. The stop
An officer can’t pull you over on a hunch. The stop needs reasonable articulable suspicion — a traffic violation, an equipment problem, or specific observations of impaired driving. If the stop itself wasn’t lawful, everything that follows can be challenged. The mobile-video recording (dashcam) and the officer’s report are where this gets tested: what did the officer actually see, and does it match what the video shows?
2. The roadside investigation and field sobriety tests
Once you’re stopped, the officer looks for the standard cues — odor, speech, eyes, fumbling for documents — and usually asks you to step out for Standardized Field Sobriety Tests: the walk-and-turn, the one-leg stand, and the horizontal gaze nystagmus (eye) test. These tests have to be administered a specific way to mean anything. They’re also affected by things that have nothing to do with alcohol: uneven pavement, your shoes, the weather, injuries, age, and nerves. How the tests were given — and whether the officer scored them correctly — is frequently contested.
3. The arrest and the 20-minute observation period
If the officer decides to arrest, you’re taken to the station for breath testing on the Alcotest 7110. Before that test, New Jersey law requires a continuous 20-minute observation period — an officer has to watch you to confirm you didn’t burp, regurgitate, eat, drink, or smoke, any of which can throw off the reading. This requirement comes straight from the New Jersey Supreme Court’s decision in State v. Chun. If that 20 minutes wasn’t truly continuous, the breath result is vulnerable.
4. The Alcotest itself
The Alcotest device has to be in proper working order, calibrated on schedule, and operated by a certified operator. The State is required to produce the machine’s calibration and certification records in discovery. Those records have known failure patterns — a lapsed calibration, a missing certificate, a temperature problem — and any of them can undermine the result. This is the technical heart of a serious DWI defense.
5. Refusal is a separate charge, not a safe harbor
Many drivers think refusing the breath test protects them. In New Jersey it does the opposite. Refusal (39:4-50.4a) is charged in addition to the DWI, with its own penalties that closely track a DWI conviction — including license consequences and an ignition interlock requirement. You can be convicted of refusal even if the DWI doesn’t stick. Refusing rarely helps; it usually compounds the problem.
The part that surprises people most: plea deals are limited
For decades New Jersey flatly banned plea bargaining of DWI charges. Since 2024, that rule has changed — limited plea agreements are now allowed in DWI cases — but they are never automatic, and a DWI still doesn’t simply get knocked down to careless driving as a favor. What creates negotiating room is the strength of the defense, which is why the procedural details above matter so much: the stop, the observation period, the calibration records. They aren’t technicalities. They’re the case.
What to do
If you’ve been arrested for DWI anywhere in New Jersey, the most important thing you can do early is preserve the evidence that helps you. Dashcam and bodycam footage and Alcotest records don’t last forever, and some have to be requested before they’re overwritten. The sooner a lawyer is looking at your case, the more of those defenses are still on the table.
We defend DWI and refusal charges in municipal courts throughout New Jersey, and the first conversation is free. If you’re facing a first offense or a second, call before your first court date so we can start preserving what matters.
Part of our complete guide: For every related New Jersey offense, claim, and defense in one place, see our NJ DWI Defense Guide.