ISS stands for "Ignition Interlock System" — a device that prevents your car from starting if it detects alcohol on your breath
When your driver's license shows an ISS restriction or notation, it 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 turn over, you blow into a tube, and if the device detects alcohol above a set threshold (usually 0.02 percent blood alcohol content), the car will not start. If you drive without the device installed, or tamper with it, you face criminal charges and license suspension.
ISS requirements are imposed by courts 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 can range from a few months to several years. During this period, you cannot legally drive any vehicle that does not have an interlock device installed, even if you own multiple cars.
Key Takeaways
- An ISS restriction on your license means you must install an ignition interlock device in any vehicle you operate, or you cannot drive it legally.
- The device measures your breath alcohol level before allowing the engine to start, and you will need to provide breath samples at random intervals while driving.
- ISS is ordered by a court as part of a DUI or DWI sentence, and the duration depends on your state's laws and your specific conviction.
- Removing, tampering with, or attempting to bypass an interlock device is a separate criminal offense that can result in additional charges and extended restrictions.
- You must pay for the device installation and monthly monitoring fees yourself — these are not covered by the court or your state.
How an ignition interlock device actually works
When you get in your car, you will see a small handheld unit (usually mounted on the dashboard or steering column) with a tube attached. Before you can start the engine, you blow into the tube for about five to ten seconds. The device analyzes your breath and either allows the ignition to engage or locks it out. If the reading is below the legal threshold, you can start the car. If it is above the threshold, the engine will not turn over, and the device may log the failed attempt.
Once you are driving, the device will ask for additional breath samples at random intervals — typically every 5 to 15 minutes. This is called a "rolling retest." You will hear a beep or see a light, and you have a set amount of time (usually 3 to 5 minutes) to provide another sample. If you do not comply, the device logs a violation and may trigger the horn or lights. A failed rolling retest does not stop the car when ready, but it creates a record that your monitoring company and the court can see.
Every month, you must bring your vehicle to a certified interlock service center so technicians can read the device data. This report shows how many times you started the car, how many breath samples you provided, and whether any violations occurred. Your monitoring company sends this report to the court, and violations can result in extended restrictions or additional penalties.
Why ISS appears on your license after a DUI or DWI
Courts order ignition interlock devices as a way to prevent repeat drunk driving while allowing you to maintain limited driving privileges. Without an interlock, a DUI conviction typically results in a full license suspension — meaning you cannot drive at all. With an interlock, you can drive to work, school, medical appointments, and other necessary places, but only in a vehicle equipped with the device.
The logic is harm reduction: the device makes it physically impossible to drive while impaired, so it protects you and others on the road. It also allows you to keep your job and meet family obligations during the restriction period. However, it is not a second chance — it is a monitored condition of your driving privileges, and violations can lead to license suspension or criminal charges.
Some states make interlock mandatory for all DUI convictions. Others impose it only for repeat offenders, high blood alcohol levels, or refusals to take a breath test. A few states allow judges discretion. The length of the interlock period also varies: some states require it for six months, others for one to three years or longer, depending on the offense and your driving history.
What you need to do to install and maintain an interlock device
Once your court order is final, you have a set window (usually 10 to 30 days, depending on your state) to have the device installed. You must go to a certified interlock service provider — your state's DMV or court will give you a list of approved vendors. You cannot use just any mechanic; the provider must be certified and authorized to report to the court.
Installation typically takes 30 minutes to an hour and costs between $100 and $200. After that, you pay a monthly monitoring fee, usually $60 to $100, which covers the data downloads and reports sent to the court. Some providers charge additional fees for rolling retests or violations. You are responsible for all costs — the court does not reimburse you, and your insurance will not cover it.
You must visit the service center every month without fail. If you miss an appointment, it counts as a violation and can trigger license suspension. If you move to a different state, you must transfer your interlock to a certified provider in that state and notify your original court. You cannot straightforward remove the device when you think your time is up — only the court can authorize removal, and you must have proof from the service provider that you completed the full term without violations.
What violations mean and how they affect your driving privileges
A violation does not necessarily mean you drove drunk. Violations include failing to show up for a monthly service appointment, tampering with or attempting to remove the device, providing a failed breath sample, missing a rolling retest, or driving a vehicle without the device installed. Even technical issues — like a malfunctioning device that you did not cause — can be logged as violations if you do not report it when ready.
One or two violations may result in a warning or a letter from your monitoring company. Multiple violations or a failed breath sample typically triggers a report to the court, which can lead to extended interlock requirements, additional fines, or license suspension. In some states, a single failed breath sample can add months to your restriction period. Tampering with the device is treated as a new criminal offense and can result in arrest and prosecution separate from your original DUI case.
Your best protection is to treat the device as non-negotiable: keep your service appointments, do not attempt to bypass or remove it, and report any technical problems to your provider when ready. Keep documentation of all service visits and any repairs. If you believe a violation was logged in error, you can request a hearing with the court to contest it, but the burden is on you to prove the violation was not your fault.
How long you will have an ISS restriction
The duration of an ISS requirement is set by your court order and varies widely by state and offense. A first-time DUI with a low blood alcohol level might result in six months of interlock. A second offense, a high blood alcohol level, or a refusal to take a breath test can mean one to three years. Some states impose interlock for five years or longer for repeat offenders or for DUI cases involving accidents or injuries.
The clock starts when you have the device installed, not when you are convicted. If you install it three months after your conviction, your three-year term begins at installation. If you accumulate violations, the court can extend your term — so a violation near the end of your period can add months or even restart the clock. Once you complete the full term without violations, you must bring proof of completion to the DMV or court to have the ISS notation removed from your license.
Some states allow "early removal" if you demonstrate a clean record for a portion of the required term — for example, six months violation-free out of a two-year requirement. You would need to petition the court and show the monitoring reports. Not all states allow this, and judges have discretion, so there is no may provide. The safest approach is to assume the full term and plan accordingly.
Removing ISS from your license once the requirement ends
When you complete your interlock term, the device company will provide you with a letter or certificate of completion. You must take this document to your state's DMV along with your driver's license. The DMV will remove the ISS notation from your license and issue you a new one without restrictions. This process usually takes a few days to a few weeks, depending on your state's processing time.
Do not assume the notation is automatically removed. You must actively request removal at the DMV — it does not happen on its own. If you continue to drive after your term ends without getting the notation removed, you are technically driving with an expired restriction, which can result in a ticket or license suspension. Once the notation is gone, you can drive any vehicle without an interlock device, but your DUI conviction remains on your driving record.
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 cannot legally operate any vehicle without an interlock device installed, regardless of who owns it. Driving someone else's car without the device is a violation and can result in criminal charges, fines, and license suspension.
What happens if the interlock device malfunctions?
Contact your service provider when ready and report the malfunction. Do not attempt to drive the vehicle or remove the device yourself. The provider will repair or replace it, usually within 24 to 48 hours. If you report the problem promptly, it typically will not be counted as a violation. If you drive the vehicle without reporting it, that is a violation.
Can I get the ISS requirement removed early?
Some states allow early removal if you petition the court and demonstrate a clean monitoring record for a set period. Not all states permit this, and judges have discretion. You would need to contact your local court or a DUI attorney to learn whether early removal is an option in your state and what the requirements are.
Do I have to pay for the interlock device myself?
Yes. Installation and monthly monitoring fees are your responsibility. Costs typically range from $100 to $200 for installation and $60 to $100 per month for monitoring. Your car insurance will not cover these costs, and the court does not reimburse you.
What if I move to another state while on an ISS restriction?
You must transfer your interlock to a certified provider in your new state and notify your original court of the change. Your monitoring will continue under the same terms, and reports will still be sent to your original court. Failure to transfer the device or notify the court is a violation.