Most people think of the ignition interlock as a punishment that lands on one person — the driver convicted of DWI. It isn’t. New Jersey wrote a separate statute, N.J.S.A. 39:4-50.19, that puts criminal exposure on the people around that driver too: the friend who blows into the device “just this once,” the family member who hands over the keys to a car with no interlock in it, and the driver who tries to work around the device.
These are the calls we get after the fact — a spouse who started the car in the driveway, a coworker who blew into the handset in a parking lot, a parent who lent out a second vehicle. None of them thought they were committing a crime. Under the statute, they were.
What the interlock actually is
An ignition interlock device is a breath-testing unit wired into a vehicle’s ignition. The driver has to give a clean sample before the engine will start, and again at random intervals while driving (“rolling retests”). Every event is logged — a failed start, a missed retest, a lockout, a power disconnect — and that log goes to the monitoring authority. The device is not a formality; it is a recording witness bolted to the dashboard.
Under N.J.S.A. 39:4-50.17, an interlock is required for DWI and breath-test refusal convictions in New Jersey. The device runs during the license-forfeiture period and then for a further stretch after driving privileges are restored — a period that ranges from a few months to several years depending on the offense, the BAC, and whether it’s a first or repeat conviction. For how the restoration side of that works, see our guide to getting your license back after a NJ DWI.
The three things N.J.S.A. 39:4-50.19 makes a crime
Subsection (b) of the statute creates a disorderly persons offense for anyone who:
- Blows into the device for someone else. The statute reaches anyone who “blows into an interlock device or otherwise starts a motor vehicle equipped with such a device for the purpose of providing an operable motor vehicle to a person who has been ordered by the court to install the device.” Starting the car counts even if you never intended to drive it yourself.
- Tampers with or circumvents the device. The language is broad — anyone who “tampers or in any way circumvents the operation of an interlock device.” Disconnecting power, using compressed air, rigging a workaround, or having the unit “serviced” by someone who disables it all fall inside it.
- Lends, rents, or leases a non-equipped vehicle. Anyone who “knowingly rents, leases or lends a motor vehicle not equipped with an interlock device to a person who has been ordered by the court to install an interlock device” is covered. This is the one that catches families off guard: the interlock is on one car, and someone hands over the keys to the other one.
A disorderly persons offense is a criminal charge in New Jersey, not a traffic ticket. It carries up to six months in county jail and a fine of up to $1,000, and unlike a motor-vehicle violation it leaves a criminal record that shows up on background checks. See our explainer on disorderly persons offenses vs. indictable crimes for where this sits in the system.
The narrow exception — and how narrow it really is
Subsection (c) carves out one situation: the prohibitions do not apply when a vehicle is started “for the purpose of safety or mechanical repair of the device or the vehicle” — provided the person subject to the court order does not operate the vehicle. That proviso is the whole exception. A mechanic starting the car in the shop is one thing. A friend who blows into the device so the DWI driver can then get behind the wheel is squarely outside it, no matter how the trip is described afterward.
Failing to install it at all
Separately, subsection (a) deals with the driver who was ordered to install an interlock and simply didn’t. That driver faces a license suspension of one year on top of whatever penalties the underlying DWI already carried — unless there is a valid reason the court accepts. Waiting it out is not a strategy. The suspension runs on top of the original one, and the interlock requirement doesn’t go away.
How these cases get defended
Interlock violation cases usually turn on the device data and on proof of state of mind, and both are contestable:
- Who actually blew? A device log records a failed or unusual sample. It does not, by itself, identify the person who provided it. Linking a specific sample to a specific person is the State’s burden.
- Was it tampering or a malfunction? Power interruptions, dead batteries, cold-weather faults, calibration problems, and service events all generate log entries that can look like circumvention. The technical record matters here the same way it does with breath-test equipment — see our page on Alcotest calibration records.
- “Knowingly.” The lending provision requires that the vehicle be lent knowingly to a person under a court interlock order. What the lender actually knew about the order is a genuine issue, not a formality.
- The safety-and-repair exception. If the vehicle was started for the device or the car itself and the restricted driver never operated it, subsection (c) applies by its own terms.
If you’re still at the front end of this — arrested, not yet sentenced — our guide on how the NJ ignition interlock requirement works covers what to expect before the device is ever installed.
Charged with an interlock violation? Call a shark.
Goldman Law Firm defends DWI and interlock cases throughout Ocean County, Monmouth County, and across New Jersey — including the people charged for helping someone else, who often had no idea the statute reached them at all. If you or a family member is facing a charge under N.J.S.A. 39:4-50.19, get a straight read on it before you say anything to anyone. Call or text 908-692-7745 — free consultation, available 24/7. See our full NJ DWI defense approach.