North Carolina Ignition Interlock Device Laws Explained

By Doug Edwards

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DUI/DWI Defense

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Last Modified on Nov 07, 2023

If you were recently charged with a DWI in North Carolina, it’s crucial that you educate yourself on Ignition Interlock Devices. In just the past few years, North Carolina has made several changes to its legislation regarding Ignition Interlock Devices. Your North Carolina DUI lawyer can explain if an IID will be required in your case.

Below, you can find North Carolina’s Ignition Interlock Device laws explained.

What Is an Ignition Interlock Device?

An ignition interlock device, more commonly known as an IID, is a handheld mechanism that tests a driver’s Blood Alcohol Concentration (BAC). IIDs work as both breathalyzers and ignition locks, meaning drivers must pass a breathalyzer test in order to unlock their ignition and start their car. To use an IID, the driver must simply blow into the mouthpiece for a few seconds to provide a breath sample. If they pass, the IID will unlock, and the driver may start their engine.

Under N.C. Gen. Stat. 20-17.8, a driver with an IID can only operate their vehicle if their BAC is below 0.02%. This unified fail point was set by recent legislation, replacing the previous dual-tier system that set different limits depending on the offense category (0.04% for certain first offenses with a BAC of 0.15 or higher; 0.00% for repeat offenders or Aggravated Level 1 sentences). If the IID detects alcohol at or above 0.02%, the driver will be locked out of the device and, consequently, their vehicle.

When Is an IID Required in North Carolina?

Generally, your North Carolina court or the NCDMV will mandate the use of an IID in these circumstances:

The Defendant Had a BAC of 0.15% or Higher

In North Carolina, no individual is allowed to operate a vehicle with a BAC of 0.08% or higher. Because 0.08% is the legal limit, the state views BAC results of 0.15% or above as gross impairment. As a result, North Carolina requires anyone convicted of DWI with a BAC of 0.15% or higher to use an IID as a condition of license restoration or any limited driving privilege issued by the court.

The Defendant Is a Repeat Offender

An IID is also required when someone is convicted of a second or subsequent DWI offense within a seven-year period. In fiscal year 2024, North Carolina recorded 24,694 DWI convictions statewide, according to the North Carolina Sentencing and Policy Advisory Commission (NCSPAC). For repeat offenders, the IID requirement applies regardless of BAC level at the time of the subsequent offense.

Felony DWI and Serious Injury Convictions (Effective December 1, 2024)

Under House Bill 199 (2024), effective December 1, 2024, an IID is now required as a condition of license restoration for anyone convicted of felony death or serious injury by vehicle under N.C.G.S. 20-141.4, including the aggravated and repeat versions of those offenses. This expansion represents a significant broadening of who is subject to North Carolina’s ignition interlock program.

How Long Must You Use an IID in North Carolina?

North Carolina law ties the IID requirement period directly to the length of the underlying license revocation under N.C.G.S. 20-17.8(c):

• One year from license restoration if the original revocation was one year (typically a first offense with a BAC of 0.15% or higher)
• Three years from license restoration if the original revocation was four years (typically a second offense within seven years)
• Seven years from license restoration if the original revocation was permanent (typically a habitual DWI or third offense)

Important: If you commit an IID violation during the final 90 days of your required period, the requirement is automatically extended for an additional 90 days, or until you have been violation-free for 90 days – whichever is longer. This 90-day final-period rule was codified under House Bill 199 and took effect July 1, 2024.

Which Vehicles Must Have an IID?

Under N.C.G.S. 20-17.8(c1), you are no longer required to install an IID on every vehicle you own. Instead, you must designate the specific vehicles you operate or intend to operate in accordance with NCDMV policies, and only those designated vehicles must be equipped. This change replaced the prior rule that required all registered vehicles to carry the device. Driving an unequipped vehicle while under an IID requirement is a criminal offense and can result in license cancellation.

Note: If you drive a company-owned vehicle for work purposes, you may be eligible for an exemption. Each case is different – speak with a DWI attorney about whether a workplace vehicle exemption applies to your situation.

IIDs and Limited Driving Privileges

One significant benefit of installing an IID is the ability to obtain a limited driving privilege (LDP) without waiting through the traditional mandatory hold period. Under the revised N.C.G.S. 20-179.3, a court cannot issue a limited driving privilege for a BAC-triggered IID requirement without proof of installation, established by providing a copy of the installation report and the associated contract with an NCDMV-certified provider.

Once the IID is installed, an Ignition Interlock Limited Driving Privilege generally allows driving at any time of day, unlike a standard limited driving privilege, which restricts driving to specific purposes and hours. 

House Bill 250 (2024) also expanded eligibility for LDPs to certain Level 2 DWI offenders (one prior offense within seven years and BAC below 0.15%), who are also required to install an IID as a condition of the privilege.

What Happens If You Fail an IID Test?

This is a preventive measure, as the device may sometimes produce a false reading, or the driver used something like mouthwash that temporarily affected the result. If you fail your initial IID test but know you did not drink, do the following:

1. Wait ten minutes
2. Drink some water
3. Try the test again

If you provide another breath sample and fail, you will most likely be locked out for another 30 minutes to an hour.

A failed test is reported to the North Carolina Division of Motor Vehicles (NCDMV) per N.C.G.S. 20-17.8(b). Repeated violations can trigger a license revocation hearing before the Division. 

A second failed attempt confirmed as a genuine alcohol violation is considered a violation of your court order and can result in the suspension of your driving privileges. If you believe your IID had multiple false readings, it is critical to speak with a DWI attorney who can evaluate the calibration records and challenge the reported violations.

How Much Does an IID Cost in North Carolina?

All IIDs used in North Carolina must be installed and monitored by an NCDMV-certified provider. Current pricing across approved providers reflects:

• Installation: $70 to $150 (one-time fee; some providers offer free installation)
• Monthly monitoring: approximately $60 to $80 per month
• Calibration: typically included in the monthly fee, required every 30 days
• Removal fee: a separate one-time charge when the device is removed at the end of your requirement period

Under N.C.G.S. 20-179.5, cost waivers or reductions are available for individuals who demonstrate financial hardship. Contact your provider or the court to determine if you qualify. In 2023, North Carolina recorded 345 fatal alcohol-related crashes, according to the NCDMV Traffic Crash Facts report – a reminder of why the state takes IID compliance seriously.

Facing an IID requirement or DWI charge in North Carolina? Contact Edwards Law, PLLC for a consultation. Schedule your consultation today.

Frequently Asked Questions: North Carolina IID Laws

What BAC level triggers a mandatory IID requirement in North Carolina?

A BAC of 0.15% or higher at the time of arrest triggers a mandatory IID requirement upon license restoration or issuance of a limited driving privilege. A second DWI conviction within seven years also triggers the requirement regardless of BAC level. The IID is set to a fail point of 0.02% under current N.C.G.S. 20-17.8(b)(3).

How long do I have to keep the IID installed?

The length depends on your license revocation period: one year if your revocation was one year, three years if the revocation was four years, and seven years if the revocation was permanent. If you violate the IID requirement in the final 90 days of your required period, the requirement is extended by at least 90 additional days.

Can I drive any car while under an IID requirement?

No. You may only drive vehicles you have designated with the NCDMV under N.C.G.S. 20-17.8(c1), and only those vehicles must have the IID installed. Driving an unequipped vehicle is a criminal offense. There may be a limited workplace vehicle exemption in certain circumstances – speak with a DWI attorney about your specific situation.

Do I need an IID to get a limited driving privilege?

Yes, if your DWI conviction involved a BAC of 0.15% or higher, or if you qualify under the expanded eligibility rules for Level 2 offenders. The court cannot issue the limited driving privilege without proof of IID installation. Once installed, the interlock LDP typically allows unrestricted driving times – a significant advantage over a standard limited privilege.

What happens if the IID records a false positive?

Wait ten minutes, rinse your mouth with water, and retest. Certain products, like mouthwash, hand sanitizer, or fermented foods, can cause brief false readings. If the retest also fails, you may be locked out for up to an hour. Multiple reported violations will be reviewed by the NCDMV, which may schedule a hearing. Document any suspected false positives and inform your attorney.

Who are the approved IID providers in North Carolina?

You must use an NCDMV-certified provider. Currently approved providers in North Carolina include Smart Start, Intoxalock, LifeSafer, and others listed on the NCDMV Ignition Interlock Program page. Using an uncertified provider can result in non-compliance and prevent license reinstatement.

What is the penalty for removing or tampering with an IID?

Tampering with or removing an IID without court or NCDMV authorization is a separate criminal offense under N.C.G.S. 20-17.8A. It can result in immediate license cancellation and additional criminal charges. Only change your provider through the approved process – notify the NCDMV and schedule installation with the new certified provider before removing the existing device.

Can my IID requirement be extended?

Yes. Under the 90-day final-period rule effective 2024, any IID violation in the last 90 days of your required period extends the requirement by at least 90 days or until you have been violation-free for 90 consecutive days. The NCDMV can also extend requirements following a hearing if other violations are substantiated.

Speak With a North Carolina DWI Attorney

At Edwards Law, PLLC, we have been defending North Carolina residents for over a decade. We understand just how overwhelming a DWI charge can be, which is why we are prepared to offer unbiased legal support at any point in your case. Attorney Doug Edwards is a Board-Certified Specialist in State Criminal Law with over 10 years of experience as an Assistant District Attorney – giving him direct insight into how prosecutors build DWI cases.

If you were recently mandated to use an IID, have questions about limited driving privileges, or have concerns regarding your DWI charge, do not hesitate to contact our firm. Reach out to Edwards Law, PLLC, to schedule a consultation today.