What Is an Ignition Interlock Device?
An ignition interlock device (IID) is a small, court-ordered breathalyzer installed in your vehicle. Before the engine starts, you must blow into the device. If it detects alcohol above a preset limit, the vehicle won’t start.
This system is meant to prevent individuals convicted of driving while impaired (DWI) from reoffending, and it’s becoming more common across the U.S. In North Carolina, ignition interlock is mandatory in many DWI cases and is regulated under North Carolina General Statutes § 20-17.8.
Whether this is your first DWI or you’ve had prior offenses, understanding North Carolina’s ignition interlock requirements is crucial for restoring your license and staying compliant with court orders.
When Is an Ignition Interlock Device Required in NC?
In North Carolina, the ignition interlock requirement depends on the severity of the offense, your blood alcohol concentration (BAC), and whether it’s a first or repeat offense.
You may be required to install an IID if:
- Your BAC was 0.15% or higher
- You’re a repeat offender
- You’re applying for limited driving privileges after a DWI conviction
- You’re seeking to reinstate your license after a suspension
First-Time Offenders
- BAC below 0.15%: No IID required unless you’re requesting limited driving privileges within 45 days.
- BAC 0.15% or above: IID required for one year minimum.
Repeat Offenders
- IID required automatically for anyone with two or more DWIs within a seven-year period.
- Duration depends on the number of offenses and the circumstances of your conviction.
How Does the Ignition Interlock Process Work?
After being ordered to install an IID, you must follow these steps:
1. Choose a State-Approved Provider
You must select an IID vendor certified by the North Carolina Division of Motor Vehicles (NCDMV). Approved providers install and monitor the devices throughout your required period.
A current list of certified vendors can be found on the NCDMV Ignition Interlock Program page.
2. Install the Device
You’ll schedule installation at an approved service center. Installation fees range from $70 to $150, and monthly monitoring costs around $60 to $80.
3. Submit Proof of Installation
Once installed, your provider will send proof to the NCDMV. You may also need to present this documentation in court or to your probation officer.
4. Follow Program Rules
You must:
- Use the device every time you start your car
- Submit to random rolling retests while driving
- Avoid tampering with or disabling the device
- Bring the vehicle for regular monitoring and data uploads
Failure to comply can result in:
- License suspension
- Extended IID period
- Probation violations
How Long Do You Need to Use an IID?
The duration of interlock requirements varies depending on the offense:
| Offense Type | Required IID Duration |
| First DWI with BAC ≥ 0.15% | 1 year |
| Second DWI | 2 years |
| Third or subsequent DWI | 7 years |
These durations apply after license reinstatement or when limited driving privileges are granted. The court or DMV may impose longer durations if aggravating factors are present.
Can You Drive Any Vehicle with an IID?
No. If you are under an interlock requirement:
- You may only drive vehicles equipped with the IID.
- Driving a non-interlock vehicle is a criminal offense and can result in jail time and permanent license revocation.
- This includes employer-owned vehicles — unless a court grants an exemption (which is rare).
Exceptions for Work Vehicles
North Carolina law allows limited exemptions for employer-owned vehicles used during work hours. However:
- You must get written approval from your employer
- The court must authorize the exemption
- You still cannot drive these vehicles for personal use
In most cases, the safest route is to avoid driving any vehicle not fitted with the ignition interlock device.
What Happens If You Fail a Test?
If the IID detects alcohol:
- The engine won’t start
- A report is sent to your monitoring agency or probation officer
- It may count as a violation of probation or court orders
Multiple failed tests can lead to:
- Extended interlock duration
- Probation revocation
- Additional criminal charges
At Martine Law, we help clients challenge interlock violations and correct issues due to false positives, medical conditions, or device errors.
Can You Challenge the Interlock Requirement?
Yes, in some cases. You can petition the court to:
- Shorten the interlock period
- Challenge the necessity of the device (especially for low-BAC, first-time offenders)
- Request modifications due to financial hardship or medical limitations
However, these petitions are rarely successful unless you have strong legal grounds. A knowledgeable attorney can help you explore your options and present the best case to the court.
Costs of the Ignition Interlock Program
Here’s a breakdown of the average costs associated with North Carolina’s ignition interlock program:
| Service | Approximate Cost |
| Installation | $70 – $150 |
| Monthly rental & monitoring | $60 – $80 |
| Removal fee | $50 – $100 |
| Early termination (if allowed) | May include penalties |
You are responsible for all costs unless you qualify for a fee waiver due to low income. Fee waiver requests can be made through the vendor or court.
Why Legal Support Matters
Facing a DWI in North Carolina is stressful enough — adding interlock requirements can feel overwhelming. That’s why it’s critical to understand your rights and obligations from the beginning.
At Martine Law, we can help you:
- Understand whether an IID is required in your case
- Secure favorable terms for limited driving privileges
- Dispute incorrect or unfair interlock violations
- Navigate court requirements, DMV rules, and legal filings
Don’t take chances with your future. We guide you through every step, from arrest to license reinstatement.
Get Legal Help Today
If you’re facing DWI charges or ignition interlock requirements in North Carolina, you don’t have to go through it alone. Contact Martine Law for a confidential consultation and start building a strategy to protect your license, record, and livelihood.