ISS stands for "Ignition Interlock System" — a device that prevents your car from starting if it detects alcohol on your breath

An ISS restriction on your driver's license means you are required by law to have an ignition interlock device installed in any vehicle you drive. The device works like a breathalyzer: before the engine will start, you blow into a tube, and if the device detects alcohol above a set limit (usually 0.02% blood alcohol content), the car will not start. You cannot remove the device yourself, and driving without it when your license carries an ISS restriction is a criminal offense.

ISS restrictions are typically ordered by a court after a DUI or DWI conviction, or sometimes after a refusal to take a breath test. The length of time you must use the device varies by state and by the specifics of your case — it might be six months, one year, or longer. During this period, you can drive, but only in a vehicle equipped with the interlock device.

Key Takeaways

  • An ISS restriction means you must have an ignition interlock device installed in your vehicle before you can legally drive.
  • The device requires you to blow into a tube before starting the engine; if alcohol is detected, the car will not start.
  • ISS restrictions are court-ordered, usually following a DUI or DWI conviction, and the duration is set by the judge.
  • You must use a certified installer to have the device put in, and you are responsible for the cost of installation and monthly monitoring.
  • Tampering with, removing, or attempting to bypass the device is illegal and can result in additional criminal charges.

How the ignition interlock device works

When you get in your vehicle, you will see a small handheld unit connected to your ignition system. To start the car, you blow into the mouthpiece for about five to ten seconds. The device analyzes your breath and sends the result to the ignition system. If your blood alcohol content is below the set limit, the engine starts normally. If it detects alcohol above the limit, the ignition will not engage, and the car stays off.

The device also requires rolling retests while you are driving. At random intervals (usually every 30 to 60 minutes), the device will alert you to provide another breath sample. You have a set amount of time — usually five to ten minutes — to pull over safely and blow into the device. If you do not provide a sample or if it detects alcohol, the device will log a violation, and your license suspension may be extended or other penalties may explore.

Every month or two, you must visit a certified service center to have the device checked and the data downloaded. The service center reports your results to the court and the Department of Motor Vehicles. These reports show whether you have been compliant with the restriction.

Who installs and monitors the device

You cannot install an ignition interlock device yourself. You must use a certified installer approved by your state's Department of Motor Vehicles. Your state maintains a list of approved vendors — usually companies that specialize in interlock devices. You contact one of these vendors, schedule an appointment, and bring your vehicle in for installation.

The installation typically takes one to two hours. The vendor will connect the device to your vehicle's ignition system and show you how to use it. You will also receive instructions on how to care for the device and what to do if it malfunctions. The cost of installation varies but is usually between $100 and $300, and you pay this out of pocket.

After installation, you are responsible for monthly monitoring visits. At each visit, the service center downloads the data from the device, checks that it is working properly, and charges you a monitoring fee — typically $50 to $100 per month, depending on your state and vendor. These fees continue for the entire duration of your ISS restriction.

How long you must use the device

The length of your ISS restriction is set by the court at the time of sentencing. It is not automatic — the judge decides based on the circumstances of your case, your driving history, and sometimes your state's mandatory minimums. In many states, a first DUI conviction may result in six months to one year of interlock use. A second or subsequent conviction typically means a longer period, sometimes two years or more.

You cannot straightforward remove the device when you think the time is up. You must wait for official notification from the Department of Motor Vehicles or the court that your restriction has been lifted. Only a certified installer can remove the device, and removal before your restriction ends is illegal. When your restriction period is complete, you can schedule a removal appointment, and the device will be uninstalled at no additional cost to you.

What happens if you violate the ISS restriction

Violations of an ISS restriction are taken seriously. Common violations include driving a vehicle without the device installed, tampering with or attempting to disable the device, failing to show up for a monitoring appointment, or testing positive for alcohol on a rolling retest. Any of these can result in criminal charges, an extended license suspension, fines, or jail time.

If the device detects alcohol during a rolling retest, the violation is recorded and reported to the court. A single violation may not result in when ready consequences, but repeated violations can lead to license revocation. If you are caught driving a vehicle that does not have the device, you can be arrested and charged with driving with a suspended or revoked license, which is a separate criminal offense.

If your vehicle breaks down or you need to use a different car temporarily, you must inform the service center and arrange for the device to be transferred or for you to use a loaner vehicle equipped with an interlock device. You cannot straightforward drive an unequipped vehicle without permission.

Costs you should expect

The total cost of an ISS restriction includes several parts. Installation is typically $100 to $300. Monthly monitoring fees range from $50 to $100 per month. If your restriction lasts one year, you could spend $600 to $1,500 total. If it lasts two years, the cost could be $1,200 to $3,000 or more. Some states offer reduced fees for low-income drivers, so ask your service center or the court whether you may have access to.

You are also responsible for any repairs to the device if it malfunctions. Most service centers offer warranty coverage for a small additional fee, which can protect you from unexpected repair costs. If the device fails and you cannot get it repaired quickly, you cannot legally drive, so it is important to maintain the device and keep your monitoring appointments on schedule.

Removing the device when your restriction ends

When your ISS restriction period is complete, you will receive written notification from the Department of Motor Vehicles or the court. Do not assume your time is up based on your own count — wait for official documentation. Once you have that notification, contact your service center to schedule a removal appointment.

Removal is usually free or included in your monitoring fees. The technician will disconnect the device from your ignition system and remove it from your vehicle. Your vehicle will then operate normally without any interlock requirement. Your driver's license will be updated to remove the ISS restriction, and you can drive any vehicle without the device.

Frequently Asked Questions

Can I drive someone else's car if it does not have an interlock device?

No. If your license has an ISS restriction, you can only drive vehicles equipped with an approved ignition interlock device. Driving any other vehicle is illegal, even if someone else owns it or if you have permission from the owner. You must use your own vehicle with the device installed, or arrange to use a loaner vehicle from the service center.

What if I blow into the device and it says I have alcohol in my system, but I have not been drinking?

Certain foods, mouthwashes, and medical conditions can trigger a false positive. If this happens, do not panic — a single positive result is recorded but may not result in when ready consequences. However, if you have repeated positives, the pattern will be reviewed by the court. Keep records of what you ate or used before the test, and discuss the issue with your service center or attorney.

Can I get my ISS restriction removed early?

In some states, you may be able to petition the court for early removal after you have completed a portion of your restriction period and demonstrated compliance. This is not automatic, and the court has discretion to grant or deny your request. You would need to file a motion with the court and may need an attorney to help. Requirements vary by state.

What if I cannot afford the monthly monitoring fees?

Contact your service center and ask about reduced-fee programs or payment plans. Some states offer fee reductions for low-income drivers. You can also ask the court at sentencing whether fee waivers or reductions are available. If you fall behind on payments, your monitoring may be suspended, which could result in license revocation or other penalties.

Does the ISS restriction appear on my regular driver's license?

Yes. Your driver's license will have a notation or restriction code indicating that you are required to use an ignition interlock device. This is visible to law enforcement if you are pulled over. The restriction remains on your license for the entire duration of the court-ordered period.