ISS stands for "Ignition Interlock System" — a device that prevents your car from starting if it detects alcohol on your breath
An ISS notation on your driver's license means you are required by law to have an ignition interlock device installed in your vehicle. The device connects to your car's ignition and requires you to blow into a mouthpiece before the engine will start. If the device detects alcohol above a set threshold — usually 0.02 percent blood alcohol content — the car will not start.
This requirement typically follows a DUI or DWI conviction, though some states impose it after a first offense and others only after a second or subsequent conviction. The specific rules depend on your state's laws and the details of your case. The ISS notation on your license is a public record that law enforcement can see during a traffic stop.
Key Takeaways
- ISS on your license means you must have an ignition interlock device installed in any vehicle you drive, and the device must be maintained throughout your required period.
- The device costs between $70 and $150 per month for installation, calibration, and monitoring, and you pay these costs yourself.
- You cannot remove the device early or drive a vehicle without one installed — doing so is a separate criminal offense in most states.
- The required period varies by state and offense history, ranging from several months to several years.
- Some states allow a "hardship exemption" for work vehicles or medical emergencies, but you must request this through the court before driving without the device.
How the ignition interlock device actually works
When you get in your car, you blow into the mouthpiece for five to ten seconds. The device measures your breath alcohol content and sends the result to a monitoring company. If your reading is below the legal threshold, the ignition unlocks and you can start the engine. If your reading is above the threshold, the ignition stays locked and you cannot start the car.
The device also requires "rolling retests" while you are driving — typically every 5 to 15 minutes. You will hear a beep or see a light, and you have a set time (usually 5 to 10 minutes) to pull over safely and provide another breath sample. If you do not test or fail the rolling retest, the device logs the violation and may trigger your horn or lights as a warning.
Every month or every few months, you must visit a service center to have the device calibrated and checked. The monitoring company downloads data from the device to confirm you have been complying with the requirement. This data is reported to the court or the state licensing authority.
Cost and who pays for the device
You are responsible for all costs associated with the ignition interlock device. Installation typically runs $50 to $150 as a one-time fee. Monthly monitoring and calibration costs range from $70 to $150 depending on your state and the service provider. Some states have set maximum fees; others allow providers to charge market rates.
If you cannot afford the device, some states allow you to request a fee reduction or waiver through the court, but this is not automatic. You will need to file a motion and provide proof of financial hardship. Even with a reduction, you are still required to have the device installed — you cannot straightforward skip the requirement.
The total cost over a typical two-year requirement period can range from $2,000 to $4,000 or more. Budget for this before your installation appointment, because the device will not be installed until payment is arranged.
How long you must keep the device installed
The required period depends on your state's laws and your offense history. A first DUI offense typically requires 6 months to 1 year of interlock use. A second offense usually requires 1 to 3 years. Some states impose longer periods for third or subsequent offenses, or if your blood alcohol content was very high at the time of arrest.
The clock starts from the date the device is installed, not from the date of your conviction or arrest. If you delay installation, your required period does not shorten — it straightforward starts later. Some states allow you to reduce your required period by demonstrating a clean compliance record (no failed tests or missed appointments), but this is at the discretion of the court or licensing authority.
Once your required period ends, you must have the device removed by a certified service center. The removal itself is free, but you are responsible for arranging the appointment. After removal, you can request that the ISS notation be removed from your license, though this may require a separate request to your state's licensing authority.
What happens if you violate the interlock requirement
Driving a vehicle without an ignition interlock device when one is required is a separate criminal offense in most states. Penalties typically include fines of $500 to $2,000, additional jail time, license suspension, and an extended interlock requirement. A violation can also result in the original DUI conviction being used against you in future cases.
Tampering with the device — attempting to bypass it, having someone else blow into it, or removing it before your required period ends — is also a criminal offense. Penalties are similar to driving without the device and may include felony charges depending on your state and prior record.
Failed breath tests and missed calibration appointments are logged by the monitoring company and reported to the court. Multiple violations can result in license suspension, extension of your interlock requirement, or additional criminal charges. Even one failed test does not automatically end your requirement, but a pattern of failures can trigger court intervention.
Hardship exemptions and limited exceptions
Some states allow a "hardship exemption" or "work exemption" if you can show that the interlock requirement creates genuine hardship — for example, if your job requires you to drive a company vehicle that cannot have a device installed. To request an exemption, you typically file a motion with the court that handled your DUI case and provide documentation of the hardship.
Approval is not may provide and varies by judge and state. Even if approved, you may be required to install the device in a personal vehicle and use that for all non-work driving. Some states require you to renew the exemption periodically or provide updated proof of hardship.
Medical emergencies are sometimes treated differently — if you need to drive to a hospital and do not have time to use a vehicle with an interlock, you may have a legal defense against a violation charge, but you should not rely on this. The safest approach is to call an ambulance or have someone else drive you.
Removing the ISS notation from your license after the requirement ends
Once your interlock requirement period is complete and the device is removed, the ISS notation does not automatically disappear from your license. You must request removal through your state's Department of Motor Vehicles or licensing authority. The process varies by state — some require a straightforward form submission, others require a court order confirming completion of the requirement.
Contact your state's DMV to learn the specific process. You will likely need to provide proof that the device was removed and that you completed your required period without major violations. Keep your removal receipt from the service center, as you may need to show it.
The ISS notation will remain visible to law enforcement during traffic stops until it is officially removed from your record. Removing it does not erase your DUI conviction, but it does show that you have fulfilled the court-ordered requirement.
Frequently Asked Questions
Can I drive someone else's car if it does not have an interlock device?
No. If ISS is on your license, you cannot operate any vehicle without an ignition interlock device installed, regardless of who owns it. This includes rental cars, borrowed vehicles, and company cars. The only exception is a court-approved hardship exemption for specific work vehicles, and even then you must follow strict conditions.
What if I fail a breath test while driving?
The device logs the failure and reports it to the monitoring company. A single failure does not automatically end your license or extend your requirement, but it is recorded. Multiple failures or a pattern of violations can trigger a report to the court, which may result in license suspension or an extended interlock period. You should contact your monitoring company to understand what the failure means for your case.
Do I have to pay for the device if I cannot afford it?
You are responsible for the cost, but you can request a fee reduction or waiver by filing a motion with the court and providing proof of financial hardship. Approval is not may provide. Even if your fees are reduced, you still must have the device installed — you cannot skip the requirement due to cost alone.
Can the interlock requirement be removed early?
In some states, you can petition the court for early removal if you demonstrate a clean compliance record with no failed tests or missed appointments. Approval depends on the judge, your state's laws, and the details of your case. You cannot remove the device yourself — any early removal must be approved by the court first.
What happens if I move to a different state?
Your interlock requirement typically follows you to the new state. You will need to have the device installed in your new state according to that state's rules and service providers. Contact your new state's DMV and the court that issued the original requirement to understand the process. Failure to comply with the requirement in your new state can result in license suspension there as well.