Alcohol Concentration Restrictions and Ignition Interlock: What’s the Law?

Among the questions I am most frequently asked is: What is the proper charge when a person violates an alcohol concentration restriction on his or her driver’s license? As soon as I answer that question, the next one comes in: Is the answer the same if the person violates an ignition interlock restriction? When I say that it is not, additional questions follow. If you too are unsure about the rules for charging and processing a person who is suspected of violating one of these types of license restrictions, I’m hoping the rest of this post will clear things up. 

Alcohol concentration restrictions. When the North Carolina Division of Motor Vehicles (DMV) restores a person’s North Carolina driver’s license after it has been revoked for impaired driving or driving by a person under 21 after consuming, the license is restored subject to certain conditions. See G.S. 20-19(c3).

  • If the person’s driver’s license was revoked for impaired driving and this is the first time the person’s license has been restored, the license is restored subject to the condition that the person not operate a vehicle with an alcohol concentration of 0.04 at any relevant time after the driving. This restriction is denoted on the person’s physical license card as Restriction 19.


  • If the person’s driver’s license was revoked for driving after consuming by a person under 21, the license is restored subject to the condition that the person not operate a vehicle with an alcohol concentration of 0.00 at any relevant time after the driving. This restriction is denoted on the person’s physical license card as Restriction 21. Restriction 21 also applies to a person whose license is restored for a second or subsequent time following a conviction of impaired driving.


  • The licensee must agree to submit to a chemical analysis (breath, blood or urine test) at the request of a law enforcement officer who has reasonable grounds to believe that the licensee is operating a motor vehicle on a highway or public vehicular area in violation of the license restrictions. The person must also agree to be transported by the law enforcement officer upon the officer’s request to the place where chemical analysis is to be administered.


Driving in violation of license restriction. G.S. 20-7(e) makes it unlawful for the holder of a restricted license to operate a motor vehicle without complying with the restriction and provides that this conduct “is the equivalent of operating a motor vehicle without a license.” Thus, a person who operates a motor vehicle in violation of an alcohol concentration restriction or who refuses to be transported for chemical testing commits the offense of failure to comply with a license restriction, a Class 3 misdemeanor.

Additional revocation. A law enforcement officer who has probable cause to believe that a person has violated a restriction imposed pursuant to G.S. 20-19(c3) must complete an affidavit indicating the restriction violated and must mail the affidavit to DMV. The form affidavit used to report such a violation is the same form used to report a person’s refusal to submit to a test of his breath, blood or urine. Upon receipt of a properly executed affidavit, DMV must notify the person that his or her driver’s license is revoked for one year.

Ignition interlock restriction. In addition to imposing alcohol concentration restrictions, DMV must require ignition interlock for drivers whose licenses are restored following a conviction for impaired driving if any of the following is true:

  • The person had an alcohol concentration of 0.15 or more;
  • The person has been convicted of another offense involving impaired driving, which occurred within seven years of the offense for which the person’s license is revoked; or
  • The person was sentenced at Aggravated Level One.


An ignition interlock restriction requires the following:

  • The licensee may operate only a vehicle that is equipped with ignition interlock.
  • The licensee must personally activate the ignition interlock system before driving the motor vehicle.
  • The license must contain an alcohol concentration restriction of (i) 0.04 if ignition interlock is required only because of a 0.15 alcohol concentration (Restriction 20); (ii) 0.00 if ignition interlock is required because of a prior conviction or an Aggravated Level One sentence (Restriction 22); or (iii) 0.00 if the ignition interlock is required because of an alcohol concentration of 0.15 and the person has been convicted of another specified alcohol-related offense based on the same circumstances (Restriction 22).


Violation of ignition interlock restriction. A person who violates an ignition interlock restriction commits the offense of driving while license revoked for impaired driving under G.S. 20-28(a1), a Class 1 misdemeanor. G.S. 20-17.8(f). If a magistrate finds probable cause for driving while license revoked based on an ignition interlock violation, the magistrate must notify the person that his or her license is suspended pending the resolution of the case and must require the person to surrender the license. (The form revocation order is AOC-CR-341.) The magistrate must also inform the person that he or she is not entitled to drive until the case is resolved.

Still have questions?  Fire away, and I’ll respond with a comment or future post.

18 thoughts on “Alcohol Concentration Restrictions and Ignition Interlock: What’s the Law?”

  1. The DWI and DUI laws now requiring the Ignition Interlock to be installed for a first offense, is now almost standard in every state. One state just recently lowered it’s legal blood alcohol limit to .05 BAC. Having the alcohol legal limit so low such as that, will also result in more drivers having to get the Ignition Interlock device penalty in order to legally drive again.

  2. In NC, what is a violation of an interlock restriction? Anytime the device registers as a fail on initial start up or during a rolling retest?

  3. Ignition Interlock devices do such a good job detecting alcohol. They even detecting mouthwash, too and, That’s a feature, not a bug – the interlocks are doing their job. It’s not necessary to sacrifice clean breath in order to avoid getting locked out of your vehicle and in possible DUI penalties.

  4. Quick question. I received a Level 5 DUI (BAC of 0.08) in 2005 and I am attempting to restore my driving privileges in 2017. I was told that for 7 years I cannot have a BAC greater than 0.4 BAC while operating a vehicle. My question is this, does the 7 year BAC restriction of 0.04 apply to my convection date (i.e., 2005) or date of license restoration (i.e., 2017). Thanks in advance for your advice.

    Best regards,

  5. If some one was convicted of a Level 5 DUI (BAC of 0.08) in 2005 and is attempting to restore their driving privileges in 2017 does the 7 year BAC restriction of 0.04 apply to the date of convection or date of license restoration?

  6. Daughter received second DUI 10/18 /15, she is now eligible to get license back if she gets ignition interlock and insurance . Even if she had a free car she can’t afford insurance and interlock devise. Is there a time frame she can wait to get license that she would not have to have interlock devise or does 1 year of ignition interlock start the day she gets her license no matter when she starts back?

  7. Daughter received second DUI on 10/18/15 . She is eligible to get license back but between the cost of the ignition interlock and insurance she is unable to afford to drive. My question is if she waits another year will she still have to have the ignition interlock device , or does the year of interlock devise start the day she gets her license.

  8. My son was just granted permission thru the NC DMV to get a license after conviction of 3rd DUI within 7 year period. He would like to move to another state for job opportunities. If he has the IID installed in the new state, will he get credit for the years he has it installed in the new state in NC? He is required to have it in the vehicle for 7 years. He was told by NC DMV that if he ever wants to get a drivers license in NC, he will have to fulfill all the requirements including the IID.

  9. If I failed a blow test before starting my car, which results in a violation and a 4 day grace period is initiated to have the device serviced, will the DMV absolutely send a letter revoking my license? Or is there a chance that first time violations do not warrant this procedure. I have a device set at .04 BAC and have not had prior violations. Thanks in advance

    • It depends upon the reason you have an IID. If it is under a Conditional Restoration, then yes, this will cause a violation notice to be sent. If you have an IID under a BAC restriction it will not cause a violation notice as it was not a rolling retest and thus not a violation. In either case you should talk with an attorney about requesting a hearing at the DMV. The machines are built as safety devices and not measuring instruments. They are very effective as safety devices but should not be relied upon as scientific measuring devices. If your machine incorrectly flags you for a suspension you need an attorney who understands how unreliable these devices are and understands how unamerican it is to have “trial by faulty device.”

  10. My boyfriend had his license restored recently. His DWI at time of restoration was 16 years old. DMV gave him interlock for 3 years….. is that even legal??? Only tickets in the last 16 since the DWI were for driving while license revoked. No further offenses for DUI or DWI…. seems a bit extreme for a 16 year old office.

  11. I got a warning at start up, I started in my driveway, and passed, went to the grocery store for maybe ten minutes, and got a warning during startup leaving the grocery store, but it let me start the car, will this affect my driving privileges

  12. It’s been seven years since my dui conviction 2nd offense will I still be required to have alcohol assessment and to use a interlock device on my vehicle before I can restore my liscense

    • If your second offense was within 7 years of the first offense then yes, there will be an interlock requirement. It does matter how long you wait, the restriction will still be there.

  13. I had my license suspended in 2017 for 4 years. Got a letter stating I can have a hearing after 2 years. Letter did not mention interlock requirement, only bac 0.000 requirement. I’m FINALLY having my hearing tomorrow morning. I’m praying I will not have to do interlock. Does anyone know – is there even the slightest chance I will get my license back free and clear tomorrow? With no interlock? I don’t want to hope if there is none. This whole thing is the worst nightmare of my life.

    • Based upon two DWI convictions withing 3 years the suspension is 4 years but can be reduced to 2 years if you win a conditional restoration. In either case (after 2 years if you get a conditional restoration, or after 4 years if you wait out the time) you must get the interlock for 3 years under “NCGS 20-17.8 (c) (2) Three years from the date of restoration if the original revocation period was four years;”
      I strongly recommend that you consult with an experience attorney before you go into a conditional restoration hearing.

  14. I was convicted of level 3 dwi in February 2013. 1st offense. Am I still required to get an interlock device to get my license now?


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