ISS stands for "Ignition Interlock System" and it's a restriction that appears on your license when you've been convicted of a DUI or DWI
An ISS restriction means your state requires you to install and use an ignition interlock device in any vehicle you drive. This device measures your breath alcohol content before the engine will start. If the device detects alcohol above a set limit — usually 0.02% — the vehicle will not start. The restriction is a court-ordered or DMV-ordered requirement, not optional, and driving without the device installed when ISS is on your license is a separate criminal offense in most states.
The ISS restriction appears on your physical license as a notation or code, and law enforcement can see it in their system when they run your license. Some states print it directly on the card; others flag it in the DMV database. Either way, you cannot legally operate a vehicle without the interlock device installed during the period your license carries this restriction.
ISS is different from a suspended or revoked license. Your license itself remains valid for identification and other purposes, but it comes with this specific driving condition. The length of time you must maintain the device varies by state and by the severity of your conviction, but typically ranges from six months to three years.
Key Takeaways
- ISS is a court or DMV requirement to install an ignition interlock device in your vehicle after a DUI or DWI conviction.
- The device prevents your car from starting if it detects alcohol on your breath above the legal threshold, usually 0.02%.
- Driving without the device installed when ISS is on your license is a separate criminal violation in most states.
- The restriction period varies by state and conviction details, but commonly lasts six months to three years.
- You must pay for the device installation and monthly monitoring fees yourself; these are not covered by the court or state.
How the Ignition Interlock Device Works
When you start your vehicle, you blow into the interlock device's mouthpiece. The device analyzes your breath and measures blood alcohol content. If the reading is below the programmed threshold — typically 0.02% — the engine starts normally. If the reading is at or above that level, the engine will not turn over, and the device records the failed attempt.
The device also requires rolling retests while you are driving. At random intervals after you have been on the road for a set time (usually 5 to 15 minutes), the device will alert you to provide another breath sample. You have a limited window — usually 5 to 10 minutes — to pull over safely and provide the sample. If you do not provide a sample or if it registers above the limit, the device logs a violation and may trigger the horn and lights to alert law enforcement.
Every month or every few months, depending on your state and the device provider, you must visit a service center to have the device downloaded and inspected. The service center checks the device for tampering and reviews your breath test history. This record is reported to the court or DMV. Repeated failed tests or missed service appointments can result in license suspension or extension of the ISS period.
State Differences in ISS Requirements
Not every state uses the term ISS or requires interlock devices for all DUI convictions. Some states call the restriction by different names or explore it only to certain offense levels. For example, a first-time DUI with a low blood alcohol content in one state might not trigger interlock, while a first offense in another state always does.
The mandatory interlock threshold also varies. Some states require the device for any DUI conviction; others only for convictions with a BAC above a certain level, such as 0.15%. A few states allow judges discretion to order interlock or to waive it under specific circumstances. Your state's DMV website or the court that handled your case will specify whether ISS applies to your conviction and for how long.
The cost structure also differs. In most states, you pay for installation (typically $100 to $300) and monthly monitoring fees (usually $60 to $100 per month). Some states cap these fees; others do not. A few states have programs to reduce costs for low-income drivers, but these are rare. You are responsible for the full cost regardless of your financial situation.
How to Remove ISS from Your License
You cannot remove ISS yourself. The restriction is lifted only by the court that imposed it or by the DMV after the mandatory period has ended and you have met all conditions. The conditions typically include completing the full interlock period without violations, paying all monitoring fees, and passing a final inspection of the device.
Once the mandatory period ends, contact the court or the DMV office that issued the restriction. You will need to provide proof that the device has been removed from your vehicle and that you completed the monitoring period without major violations. Some states require you to file a formal petition; others straightforward require you to request the restriction be lifted once the time has passed. The DMV will then issue a new license without the ISS notation, usually within one to two weeks.
If you have violations during the interlock period — such as failed breath tests, missed service appointments, or attempts to tamper with the device — the court may extend the ISS period or impose additional penalties. The length of extension varies by state and the severity of the violation, but can range from several months to a full year.
Driving with ISS: What You Need to Know
You can drive any vehicle you own or regularly operate, but the interlock device must be installed in that vehicle. If you drive multiple vehicles, you may need to install the device in each one, or you may be limited to driving only one designated vehicle. Check your court order or contact your state DMV to confirm the rules for your situation.
The device is visible inside the vehicle, usually mounted near the steering column or dashboard. Passengers will see it. Some employers and insurance companies are notified of the ISS restriction, depending on your state and the nature of your job. Commercial drivers and drivers in safety-sensitive positions may face additional restrictions or job loss.
You are responsible for maintaining the device in working order and keeping all service appointments. If the device malfunctions, you must have it serviced when ready — you cannot drive without it. If you miss a service appointment, the device may be flagged as non-compliant, and the DMV may suspend your license until you reschedule and complete the service.
Common Mistakes That Extend ISS Periods
The most common mistake is missing a scheduled service appointment. Even one missed appointment can trigger a violation report to the court and may result in extension of your ISS period. Mark your service dates on a calendar and set phone reminders. If you cannot make an appointment, contact the service center in advance to reschedule.
Another frequent error is failing rolling retests while driving. If you are pulled over for a traffic stop and the officer sees a failed retest in the device history, you may face additional charges. Rolling retests are mandatory — you cannot ignore the alert or delay providing a sample. If you cannot safely pull over, continue to a safe location, but do not delay longer than the allowed window.
Attempting to tamper with, bypass, or disable the device is a felony in most states and will result in when ready license suspension and criminal charges. This includes asking someone else to blow into the device for you. The device records all activity and reports tampering attempts to the monitoring service and the court.
Frequently Asked Questions
Can I get the ISS restriction removed early?
Some states allow early removal if you have completed at least half the mandatory period with no violations and can show the court that you have completed a substance abuse treatment program. You must petition the court that imposed the restriction. Early removal is not automatic and depends on your state's laws and the judge's discretion. Contact the court directly to ask about your options.
What happens if I drive without the interlock device installed?
Driving without the device when ISS is on your license is a separate criminal offense, usually charged as a misdemeanor. You may face fines, jail time, and extension of your ISS period. Your license may also be suspended. Law enforcement can see the ISS restriction when they run your license, so the violation is easily discovered.
Do I have to tell my employer about ISS?
You are not required to tell your employer unless your job involves driving a company vehicle or you work in a safety-sensitive position. However, if your employer discovers the restriction through a background check or motor vehicle record review, you may face discipline or termination depending on your company's policies. Some employers require disclosure; check your employee handbook or ask HR.
Can I use a rental car or borrow someone else's vehicle?
No. If ISS is on your license, you can only drive vehicles with the interlock device installed. Renting a car or borrowing a vehicle without the device is illegal and constitutes driving with a suspended or restricted license. If you need to rent a vehicle, ask the rental company whether they have vehicles with interlock devices already installed, though most do not.
What if the interlock device gives a false positive?
Device malfunctions or false readings can happen, but they are rare. If you believe the device is malfunctioning, contact the service center when ready and request a calibration check. Keep records of any failed tests you believe were inaccurate. If a pattern of false readings emerges, you can petition the court to review the device history, but you will need technical evidence to support your claim.