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DWI Testing in New Jersey: Breath, Blood & Field Sobriety
Introduction to DWI Testing in New Jersey
Being pulled over for suspected DWI in New Jersey can be a daunting experience. Police officers use a combination of observations, field sobriety tests, and chemical testing to determine whether an individual is impaired.
But these methods are far from perfect. Each type of test comes with reliability concerns, legal requirements, and potential defenses. Understanding how DWI testing in New Jersey can help you protect your rights and avoid unfair penalties.
DUI vs. DWI in New Jersey: Why Testing Results Matter
If you searched for “DUI testing in New Jersey,” you probably noticed that most resources — including this one — refer to DWI testing instead. That’s because:
- New Jersey law uses the term DWI (Driving While Intoxicated) under N.J.S.A. 39:4-50.
- DUI (Driving Under the Influence) is standard in other states, but the charge is always called a DWI in New Jersey.
The critical thing to understand is that whether someone says “DUI test” or “DWI test,” they are talking about the same set of procedures:
- Field sobriety exercises (balance and coordination tests)
- Breath testing on the Alcotest 7110
- Blood or urine chemical testing
In short, DWI is the correct legal charge in New Jersey, but DUI and DWI testing describe the same types of police evidence. Knowing that distinction can help you understand what you read online and prepare for what happens after a traffic stop.
Review our guide on DWI checkpoints in New Jersey.
Overview of DWI Evidence in New Jersey
In most New Jersey DWI cases, prosecutors rely on a mix of evidence:
- Driving & Personal Behavior: Erratic driving, slurred speech, or red eyes.
- Field Sobriety Tests: Standardized coordination and balance exercises.
- Breath Tests (Alcotest 7110): Device-measured blood alcohol concentration (BAC). – (Alcotest 9510 is pending court approval on Daubert Challenge)
- Blood & Urine Tests: Laboratory analysis for alcohol or drugs.
Each form of evidence has unique weaknesses. Observations can be subjective, and even machine-based testing may be prone to error. A strong legal defense directly addresses these weaknesses.
Other Evidence Used in DWI Investigations
Beyond chemical and sobriety testing, officers often rely on other observations to determine if an individual is intoxicated.
Driving Behavior
Weaving, speeding, or failing to signal may justify a stop, but these actions may also result from road hazards, adverse weather conditions, or mechanical issues.
Personal Behavior
Officers look for signs like fumbling for documents, slurred speech, or the odor of alcohol. Stress, fatigue, or medical conditions can mimic these behaviors.
Incriminating Statements
You are only required to provide your license, registration, and insurance. Any further statements, such as “I had a couple of drinks,” may be used against you — even if taken out of context or without proper Miranda warnings.
While these observations are essential, most New Jersey DWI prosecutions hinge on the testing of evidence.
New Jersey Field Sobriety Tests and Reliability Issues
Common Field Sobriety Tests
- Horizontal Gaze Nystagmus (HGN): Tracks involuntary eye movement.
- Walk-and-Turn (WAT): Measures balance and ability to follow instructions.
- One-Leg Stand (OLS): Assesses coordination and stability.
Reliability Concerns
Field sobriety tests are notoriously unreliable. Anxiety, medical issues, footwear, or uneven pavement can lead to “failing” results even if a driver is sober.
Refusing Field Sobriety Tests in NJ
Unlike breath tests, there is no direct penalty for refusing field sobriety tests in New Jersey. However, refusal may give an officer more reason to escalate the investigation with chemical testing.
NJ Breath Test (Alcotest 7110) and Refusal Penalties
Implied Consent & BAC Standards
Under N.J.S.A. 39:4-50.2, drivers give implied consent to breath testing. Legal BAC limits include:
- 0.08% for most drivers.
- 0.04% for CDL drivers (Commercial Driver’s License).
- 0.01% for underage drivers under N.J.S.A. 39:4-50.14.
How the Alcotest Testing Works
The Alcotest 7110 is the only approved breath-testing device in New Jersey. It must be calibrated appropriately; only certified operators can administer the test. The Alcotest 9510 is before the New Jersey State Supreme Court in State v. Cunningham. Attorney James Abate is one of the attorneys litigating that matter before the state supreme court.
Defense Against Alcotest Results
- Residual mouth alcohol (e.g., from recent drinking or mouthwash).
- Medical issues such as GERD.
- Calibration or maintenance errors.
- Operator mistakes during administration.
NJ Breath Test Refusal Penalties
Refusing a breath test triggers penalties under N.J.S.A. 39:4-50.4a, including:
- Fines and court costs.
- License suspension.
- MVC surcharges.
Even if you never blow into the device, the law can still punish you severely for refusal.
Blood & Urine Testing for DWI in New Jersey
Blood Tests
Blood alcohol testing typically requires either consent or a warrant. The results may be inadmissible if a missing warrant or the chain of custody is broken.
Urine Tests
Used mainly in suspected drug-related DWIs, urine testing is less reliable than blood tests and is vulnerable to contamination and misinterpretation.
NJ Blood Test Warrant Rules
Following the U.S. Supreme Court case Missouri v. McNeely, New Jersey generally requires warrants for forced blood draws unless specific exceptions apply.
Common Defense Strategies
- Lab handling errors.
- Contaminated or improperly stored samples.
- Lack of proper consent or a valid warrant.
- Medical conditions affect test results.
Review our guide on: New Jersey DWI Defense Strategies That Work.
Key Legal Considerations for New Jersey DWI Testing
- Probable cause is required before ordering chemical testing.
- Refusal penalties vary depending on the test, including field sobriety, breath, and blood tests.
- Courts often view chemical evidence as stronger than officer observations, but both are subject to challenge and scrutiny.
New Jersey DWI Testing FAQ
General
How do police prove sobriety in court?
Through a combination of observations, field sobriety exercises, and chemical tests.
Do officers need probable cause before testing?
Yes. Without probable cause, DWI evidence may be thrown out.
Can you refuse DWI tests in NJ?
You may refuse field sobriety tests without penalty. Refusing a breath test carries strict penalties, while refusing a blood test generally requires a warrant to be issued.
Field Sobriety Tests
Are field sobriety tests required in New Jersey?
No. They are voluntary, although refusal may prompt officers to consider chemical testing.
What if I fail a test, but I’m sober?
Medical conditions, nerves, or uneven testing environments can all cause sober drivers to fail.
Breath & Chemical Tests
How accurate are Alcotests and blood tests?
Blood tests are more reliable than breath or urine tests, but all have potential flaws.
What’s the difference between breath, blood, and urine tests?
Breath tests detect alcohol on your breath, blood tests measure BAC directly, and urine tests mainly detect drugs.
Can I refuse a blood or urine test?
Generally, yes, unless officers have a valid warrant.
Legal & Defense
Can an attorney challenge DWI test results?
Yes. Defense attorneys may challenge procedures, the basis of probable cause, calibration, or the handling of samples.
Can I be arrested if I pass a sobriety test?
Yes, if other evidence points to impairment — though this can often be challenged.
What are common DWI defenses?
Faulty testing equipment, officer error, improper warrants, medical conditions, and chain-of-custody problems.
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Talk to a New Jersey DWI Defense Attorney
Failing or refusing a DWI test in New Jersey does not automatically mean a conviction. Every case depends on the strength of the evidence, and that evidence can be challenged.
Our New Jersey DUI attorney understand the science, procedures, and legal strategies needed to fight unreliable test results. Call today for a free consultation and protect your driving record and future.
Call us today at (908) 561-5577 or contact us. Your initial consultation will take place over the phone, and you can schedule an appointment at one of our office locations across New Jersey.
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