ISS stands for "Ignition Interlock System" — a device that prevents a 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 is a breathalyzer connected to your car's ignition. Before the engine will start, you blow into the device. If it detects alcohol above a set threshold — usually 0.02 percent blood alcohol content, well below the legal driving limit of 0.08 — the car will not start.
ISS appears on your license as a restriction code, typically printed on the back or in the restrictions section of your card. It is ordered by a court as a condition of a DUI or DWI conviction, or sometimes as part of a plea agreement or probation. The restriction stays on your license for the length of time the court specifies, which varies by state and by the details of your case.
You cannot legally drive without the device installed during the restriction period, even if you are not under the influence. Driving without it — or tampering with it — is a separate criminal offense and will result in additional penalties.
Key Takeaways
- ISS is a court-ordered requirement to install a breathalyzer device in your vehicle before you can start the engine.
- The restriction appears on your license and is mandatory for the entire period the court sets, which is usually one to three years depending on your state and conviction details.
- You must pay for the device installation and monthly monitoring fees yourself — costs range from $100 to $300 for installation and $50 to $100 per month.
- Driving without the device installed, or attempting to bypass it, is a criminal offense separate from your original DUI charge.
- Once you complete the required period and the court removes the restriction, you must request a new license from your state DMV to have the ISS code removed.
How ISS gets ordered and what triggers it
A court orders ISS as part of sentencing after a DUI or DWI conviction. In some states, it is mandatory for all DUI convictions. In others, it is discretionary — the judge decides based on factors like your blood alcohol level at the time of arrest, whether you caused an accident, and whether you have prior DUI convictions.
Some states also allow ISS as an alternative to license suspension. For example, instead of losing your license for six months, you might be allowed to keep it if you agree to use an interlock device for a longer period. This is sometimes called a "work permit" or "hardship license" with an ISS requirement.
The court order will specify exactly how long the ISS requirement lasts. This is not the same as your license suspension period. You might be suspended for three months but required to use ISS for two years after the suspension ends. Read your court paperwork carefully — it will say when ISS begins and when it ends.
How the ignition interlock device works
The device is about the size of a car radio and is wired into your vehicle's ignition system. When you get in the car, you blow into a mouthpiece. The device measures your breath alcohol content and sends a signal to the ignition. If your reading is below the threshold, the car starts normally. If it is above the threshold, the ignition locks and the car will not start.
Most devices also require a "rolling retest" while you are driving — typically every 5 to 15 minutes. You will hear a tone or see a light telling you to provide another breath sample. You have a set time (usually 3 to 5 minutes) to pull over safely and blow into the device. If you do not provide a sample or if the sample shows alcohol, the device logs a violation and may honk the horn or flash the lights to alert you.
The device stores all test results and violations in its memory. A monitoring company downloads this data monthly or whenever you bring the car in for service. The monitoring company reports the results to the court and to your probation officer, if you have one. Violations — failed tests, missed tests, or attempts to tamper with the device — are reported when ready and can result in extended ISS requirements or criminal charges.
Who installs and monitors the device
Your state's court or DMV will provide you with a list of approved ISS providers in your area. You must use a provider on that list — you cannot install a device yourself or use an unapproved vendor. Common national providers include SCRAM, Draeger, and SmartStart, but your state may have different approved vendors.
Contact an approved provider to schedule installation. You will need to bring your vehicle and proof of your court order. Installation typically takes 30 minutes to an hour. The provider will explain how to use the device and give you a schedule for monthly monitoring visits.
At each monitoring visit, the provider downloads the device data, checks that it is working correctly, and collects your monthly fee. Some providers also offer remote monitoring, where you can submit breath samples from home using a portable device, though this varies by state and provider.
Costs and who pays
You are responsible for all costs associated with ISS. Installation fees range from $100 to $300 depending on your vehicle and your provider. Monthly monitoring fees range from $50 to $100, though some providers charge more. Over a two-year ISS requirement, total costs can reach $1,500 to $2,500.
Some states have programs that reduce or waive ISS fees for people with low income, but these are not common. Contact your local court or probation office to ask whether your state offers fee reduction. You can also ask your ISS provider whether they offer payment plans.
If you cannot afford the device, you still cannot legally drive without it during the restriction period. If you cannot pay for installation, tell the court — they may extend your license suspension instead, or they may refer you to a fee-waiver program. Do not straightforward ignore the requirement.
What happens when your ISS period ends
When the court-ordered period ends, the ISS requirement is lifted, but the restriction code will still appear on your current license. You must request a new license from your state DMV to have the ISS code removed. You cannot straightforward stop using the device — you must formally end the monitoring relationship with your provider and then get a new license card.
Contact your ISS provider and tell them the end date of your court order. They will remove the device from your vehicle and close your account. Then go to your state DMV with proof that the court order has ended (usually a letter from the court or probation office) and request a license renewal or replacement. The new license will not have the ISS restriction.
If you drive without removing the device after the court order ends, you are not breaking the law — but you are still paying for a service you no longer need. If you continue to drive with the device installed after the order ends and you have not obtained a new license, the ISS code will still appear on your old license if you are stopped by police, which can cause confusion.
Violations and what they mean for your license
A violation is recorded whenever you fail a breath test, miss a scheduled test, or attempt to tamper with or bypass the device. Common violations include blowing above the threshold, not providing a sample during a rolling retest, or trying to start the car multiple times in a short period (which the device interprets as tampering).
One or two violations may not result in when ready consequences, but the monitoring company reports all violations to the court and your probation officer. The court can respond by extending your ISS requirement, adding additional probation conditions, or filing new criminal charges if the violation is serious.
Attempting to disable, bypass, or tamper with the device is a separate criminal offense in all states. This includes asking someone else to blow into the device for you, disconnecting wires, or using a different vehicle without a device installed. These actions can result in jail time, fines, and a new DUI charge.
ISS versus other DUI license restrictions
ISS is one of several restrictions that can appear on a DUI-related license. Other common restrictions include a suspension (you cannot drive at all), a hardship or work permit (you can drive only to work or court), or an alcohol monitoring requirement (you wear a SCRAM ankle bracelet that detects alcohol through your skin).
ISS is different because it is vehicle-specific — it only prevents you from starting a car with the device. It does not prevent you from riding as a passenger, using public transportation, or driving a rental car (though rental companies often refuse to rent to people with ISS requirements). A suspension, by contrast, prevents you from driving any vehicle at all.
Some people prefer ISS to suspension because it allows them to keep working and driving. Others find it more intrusive because the device monitors every trip. The court decides which restriction is appropriate based on your case.
Frequently Asked Questions
Can I drive someone else's car if it does not have an interlock device?
No. Your court order requires you to drive only vehicles with an approved ISS device installed. Driving any other vehicle is a violation of your court order and a criminal offense. This includes borrowing a friend's car, renting a vehicle, or driving a company car. You can ride as a passenger, but you cannot operate the vehicle.
What if I cannot afford the monthly monitoring fees?
Tell your ISS provider and your probation officer when ready. Some providers offer payment plans or reduced fees for financial hardship. A few states have programs that reduce or waive fees for low-income people. If you stop paying without permission, the provider will report it to the court as a violation. Do not ignore the bill.
Can I have the ISS requirement removed early?
Only the court can remove or shorten an ISS requirement. In some states, you can petition the court for early removal after you have completed part of the requirement and demonstrated compliance. This is not common, and the court will deny most requests. Talk to your probation officer or attorney about whether your state allows early removal petitions.
Does ISS show up on background checks or employment records?
ISS is a license restriction, not a separate criminal record. It will not appear on a standard background check. However, if an employer runs a driving record check (common for jobs involving driving), they will see the ISS restriction and the underlying DUI conviction. Some employers will not hire people with DUI convictions or active ISS requirements.
What if the device malfunctions or gives a false reading?
Contact your ISS provider when ready. They can read the device data and see what happened. If the device malfunctioned, the provider can repair or replace it. If you believe you received a false positive, tell your provider and your probation officer — they may investigate, but a single disputed reading is usually not enough to overturn a violation report. Keep records of any malfunctions.