What Breath Test Machine Do Police Use in New Jersey?
If you are arrested for DWI in New Jersey, one of the most important pieces of evidence the State may rely on is the breath test. Today, most New Jersey law enforcement agencies use the Alcotest 9510 as their evidential breath-testing device.
However, New Jersey’s breath-testing system did not appear overnight. It evolved through multiple generations of devices, each bringing new technology—and new legal challenges.
Understanding what machine was used, how it works, and whether it is legally admissible can make a critical difference in a NJ DWI case.
Quick Answer: The Current NJ Breath Test Machine
Most police departments in New Jersey now use the Dräger Alcotest 9510 to measure a driver’s blood alcohol concentration (BAC) in DWI cases.
The Alcotest 9510 replaced earlier Alcotest models and is intended to serve as the State’s current evidential breath-testing instrument. However, unlike prior machines, the Alcotest 9510 has not yet been approved by the New Jersey Supreme Court as scientifically reliable through a final, statewide decision.
A Brief History of Breath Testing in New Jersey
Early Breathalyzer Devices
For decades, New Jersey relied on earlier “Breathalyzer” devices to measure alcohol concentration. These machines laid the foundation for breath-test evidence in DWI prosecutions but were eventually replaced as technology advanced.
The Alcotest 7110 and State v. Chun
The modern framework for breath-test admissibility in New Jersey comes from the New Jersey Supreme Court’s 2008 decision in State v. Chun.
That case addressed the Alcotest 7110 MKIII-C, the machine in use at the time. After extensive hearings and expert testimony, the Court ruled that the Alcotest 7110 was scientifically reliable subject to strict conditions, including:
- Mandatory calibration and maintenance protocols
- Required foundational documents
- Specific operator procedures
- Data transparency and discovery obligations
For years, State v. Chun governed how Alcotest breath results were admitted—or excluded—in New Jersey DWI cases.
Transition From the Alcotest 7110 to the Alcotest 9510
As technology progressed, New Jersey transitioned away from the Alcotest 7110 and toward the Alcotest 9510, a newer and more advanced breath-testing instrument.
The transition raised an obvious legal question:
Is the Alcotest 9510 scientifically reliable and admissible under New Jersey law?
That question was never answered in Chun, because Chun applied only to the 7110, not the 9510.
The Alcotest 9510 and the Cunningham Litigation
To address the reliability of the Alcotest 9510, the New Jersey Supreme Court directly certified State v. Cunningham and appointed a Special Adjudicator to develop a full scientific record.
While that litigation was pending, the Court imposed a limited statewide stay affecting certain DWI cases relying on Alcotest 9510 results.
What Happened to Cunningham?
In December 2025, the New Jersey Supreme Court dismissed the Cunningham appeal after the defendant withdrew her challenge. Because the case ended without a merits decision, the Court did not issue a final ruling declaring the Alcotest 9510 scientifically reliable.
The Court also lifted the limited stay, allowing prosecutions to proceed.
Why This Matters
As of now:
- There is no statewide NJ Supreme Court decision approving the Alcotest 9510 in the way Chun approved the 7110
- Alcotest 9510 results are being used in prosecutions
- Defendants may still challenge reliability and admissibility on a case-by-case basis
What Is the Alcotest 9510?
The Dräger Alcotest 9510 is an evidential breath-alcohol testing device designed for law-enforcement use. It was developed to meet international breath-testing standards and incorporates dual-sensor technology.
Unlike earlier machines, the Alcotest 9510 measures alcohol using two independent analytical methods.
How the Alcotest 9510 Works (In Detail)
1. Dual Sensor Technology
The Alcotest 9510 uses:
- Infrared (IR) spectroscopy
- Electrochemical fuel cell analysis
Both sensors analyze the same breath sample.
2. Infrared (IR) Spectroscopy
Infrared spectroscopy measures how ethanol absorbs infrared light at specific wavelengths. The machine analyzes this absorption to estimate alcohol concentration.
IR analysis is designed to:
- Detect ethanol based on molecular absorption patterns
- Reduce the influence of certain non-alcohol substances
- Provide a rapid measurement of breath alcohol content
3. Fuel Cell (Electrochemical) Analysis
The fuel cell sensor measures alcohol through a chemical reaction that generates an electrical current proportional to the amount of ethanol present in the breath sample.
Fuel cells are commonly used in evidential devices because they are:
- Highly specific to ethanol
- Less sensitive to some environmental interferents
- Capable of producing stable measurements
4. Cross-Checking the Results
One purpose of using two sensors is cross-validation. The machine compares results from the IR and fuel cell analyses to determine whether they fall within acceptable parameters.
If the results do not align or if certain thresholds are triggered, the device may:
- Flag an error
- Abort the test
- Require additional procedures
5. Mouth Alcohol and Breath Quality Safeguards
The Alcotest 9510 includes software and procedural safeguards intended to reduce the risk of measuring mouth alcohol rather than deep-lung breath.
These safeguards typically involve:
- Observation periods
- Breath-sample quality requirements
- Internal checks for irregular breath patterns
Whether those safeguards functioned properly in a specific case can become a central issue in litigation.
Why Breath Test Evidence Is Still Challenged
Even with advanced machines, breath-test results are not automatically admissible. Common issues include:
- Missing or incomplete calibration records
- Maintenance or repair problems
- Operator error or protocol violations
- Software or diagnostic warnings
- Timing issues and observation period failures
In many DWI cases, the real question is not “What machine was used?” but “Was this machine properly maintained and operated on this date?”
Key Takeaways for New Jersey DWI Cases
- New Jersey currently uses the Alcotest 9510 as its primary evidential breath-testing device
- The earlier Alcotest 7110 was approved under State v. Chun, but that ruling does not automatically apply to the 9510
- The Cunningham litigation was dismissed without a final scientific-reliability ruling
- Breath-test evidence may still be challenged depending on the facts, records, and procedures involved
Speak With a Former New Jersey Prosecutor
New Jersey police use the Alcotest 9510 breath test machine in DWI cases. Learn the history of NJ breath testing, State v. Chun, and how the Alcotest 9510 works.I’m Anthony J. Vecchio, I’ve prosecuted and defended thousands of NJ DUI cases. Breath-test cases are technical, document-heavy, and highly litigated. As a former municipal prosecutor, I understand how these cases are built—and where they are vulnerable.
If you were arrested for DWI in New Jersey and a breath test was involved, what you do next matters.
Consultations are free, confidential, and available 24/7.
Anthony J. Vecchio, Esq.
New Jersey DUI & Criminal Defense Attorney
Former Municipal Prosecutor
Law Office of Anthony J. Vecchio, LLC
Last updated: February 5, 2026
