What a Smart Start interlock does and why courts order them

A Smart Start interlock is a breath-testing device installed in your vehicle that prevents the engine from starting if it detects alcohol on your breath. The device measures your blood alcohol content (BAC) through a breath sample you provide before the car will turn on. If the reading is above the set threshold — typically 0.02 percent, well below the legal driving limit of 0.08 percent — the ignition locks and the vehicle will not start.

Courts order interlock installation as a condition of keeping your driving privileges after a DUI or DWI conviction. The device creates a record of every start attempt, breath sample, and result, which is reported to the court and your probation officer. This monitoring serves as both a deterrent and a way for the court to verify you are not driving under the influence during your probation period.

Smart Start is one of several interlock manufacturers approved by state motor vehicle departments. Other major providers include LifeSafer, Draeger, and Alcohol Detection Systems (ADS). Your state's Department of Motor Vehicles or the court handling your case will specify which vendors are approved in your jurisdiction, and you typically have the right to choose among them.

Key Takeaways

  • Smart Start interlocks require a breath sample before your vehicle will start, and the device records all attempts for court review.
  • Installation costs range from $100 to $300, with monthly monitoring fees typically between $50 and $100, depending on your state and the specific device.
  • You are responsible for all costs associated with the interlock, including installation, monthly service, calibration, and removal.
  • The length of time you must use the device is set by the court and varies by state, offense severity, and prior DUI history.
  • Tampering with, bypassing, or attempting to circumvent the device can result in extended probation, additional fines, and criminal charges.

Installation, costs, and monthly maintenance

Smart Start installation typically takes 30 minutes to one hour at an authorized service center. You will need to schedule an appointment, bring your vehicle, and provide proof of insurance and a valid driver's license. The installation fee ranges from $100 to $300 depending on your state and whether your vehicle has a standard or more complex electrical system.

Monthly monitoring and calibration fees vary by state but typically fall between $50 and $100. This fee covers the monthly data read (which the device sends to Smart Start's servers for court reporting), calibration checks to may support the device is reading accurately, and customer service. Some states cap the monthly fee; others do not. You pay these fees for the entire duration of your interlock requirement, which can range from six months to three years or longer depending on your conviction and state law.

Additional costs include removal of the device when your probation ends, which typically costs $50 to $100. If you fail a breath test or tamper with the device, you may face reinstatement fees or extended monitoring periods, which add to the total cost. Some states offer fee waivers or reductions for low-income individuals, but you must request this through the court or your probation officer.

How the breath test and rolling retests work

When you start your vehicle, Smart Start prompts you to provide a breath sample into the mouthpiece. You blow steadily for several seconds until the device has enough air to analyze. The device measures your BAC and displays the result on a small screen. If your BAC is below the set threshold (usually 0.02 percent), the vehicle starts normally. If it is above the threshold, the ignition locks, and you cannot start the engine.

Once the vehicle is running, the device may prompt you for a rolling retest at random intervals — typically every 5 to 15 minutes of driving. This prevents someone else from providing the initial breath sample and then you driving after drinking. If you receive a rolling retest prompt and do not provide a sample within a set time (usually 3 to 5 minutes), the device logs a violation, sounds an alarm, and may flash the lights or honk the horn to alert you and others on the road. The vehicle continues to run, but the violation is recorded and reported to the court.

Failing a rolling retest — meaning your BAC is above the threshold — also logs a violation. A single violation does not automatically result in license suspension, but multiple violations within a monitoring period can trigger court action, extended probation, or additional penalties.

What happens if you fail a test or miss a service appointment

A failed breath test is recorded in the device's data log and transmitted to Smart Start's monitoring center. The court and your probation officer receive a report of all failed tests. One failed test typically does not result in when ready consequences, but the pattern matters. If you accumulate multiple failed tests over weeks or months, the court may interpret this as a violation of your probation conditions.

Consequences for repeated violations vary by state and judge but can include extension of your interlock requirement, increased monitoring fees, additional fines, loss of driving privileges, or even jail time. Some courts use a threshold — for example, three failed tests in 30 days — before taking action. Others review the data monthly and make decisions based on the overall pattern.

Missing a scheduled monthly service appointment is also a violation. Smart Start sends you appointment reminders, but you are responsible for scheduling and attending. If you miss an appointment, the device may lock or stop functioning, and the missed service is reported to the court. Repeated missed appointments can result in probation violations and the same consequences as failed tests.

Tampering, bypassing, and what counts as a violation

Tampering with or attempting to bypass the interlock device is a separate criminal offense in most states, distinct from your original DUI conviction. Tampering includes disconnecting wires, removing the device without authorization, introducing foreign substances into the mouthpiece, or using a device designed to defeat the breath test (sometimes called a "bypass kit").

The interlock device is designed to detect tampering. If it senses an attempt to disconnect it, bypass it, or interfere with its sensors, it logs a tamper violation and alerts the monitoring center. These violations are reported to the court and probation officer when ready. A single tamper violation can result in criminal charges for tampering, extension of your interlock requirement by months or years, substantial fines, and possible jail time.

Other violations include driving a vehicle without an interlock when one is required, allowing someone else to drive your vehicle (even if they provide their own breath sample), and providing a breath sample you know is not your own. Each of these can be charged as a separate offense and may result in additional criminal penalties beyond your original DUI sentence.

How long you must use the device

The length of your interlock requirement is set by the court at sentencing and varies based on your state's DUI laws, the severity of your offense, your BAC level at the time of arrest, and your prior DUI history. A first-time DUI conviction typically requires 6 to 12 months of interlock use. A second conviction within a certain period (often 5 to 10 years) may require 12 to 24 months. A third or subsequent conviction can require 24 months to several years.

Some states allow you to petition the court for early removal after you have completed a portion of your requirement — often 50 percent or more — if you have a clean record with no violations. Other states do not allow early removal and require the full term. You must check with your probation officer or the court to learn whether early removal is an option in your case and what conditions you must meet.

When your interlock requirement ends, you must schedule a removal appointment with Smart Start or an authorized service center. The device is uninstalled, and your vehicle returns to normal operation. The court receives confirmation of removal, and your probation officer updates your file.

Choosing between Smart Start and other approved vendors

Your state's Department of Motor Vehicles maintains a list of approved interlock vendors. In most states, you have the right to choose which vendor to use, as long as they are on the approved list. Smart Start is the largest provider nationally, but LifeSafer, Draeger, and ADS are also widely available.

The devices themselves function similarly — all measure breath alcohol, record data, and report to the court. The differences lie in customer service, appointment availability, monthly fees, and the user interface of the device itself. Some vendors offer more flexible appointment scheduling or lower monthly fees in certain states. Before choosing, contact a few vendors in your area, ask about their monthly fees, appointment availability, and customer service options.

Your choice of vendor does not affect your legal obligations or the court's monitoring of your compliance. Switching vendors during your interlock requirement is possible but requires court approval in some states and involves reinstallation fees. Check with your probation officer before switching.

Frequently Asked Questions

Can I drive someone else's car while I have an interlock requirement?

No. Your interlock requirement applies to any vehicle you operate, not just the one with the device installed. Driving a vehicle without an interlock when one is required is a violation and can result in additional criminal charges. You are limited to driving only the vehicle with the installed interlock.

What if I blow into the device and it says I have alcohol in my system but I did not drink?

False positives can occur due to mouthwash, certain foods, medical conditions, or device calibration issues. If you believe a test result is inaccurate, document the circumstances and report it to Smart Start and your probation officer when ready. Request a calibration check at your next service appointment. One disputed result is unlikely to result in consequences, but a pattern of disputed results may require a hearing before the court.

Do I have to pay for the interlock if I cannot afford it?

Some states and courts offer fee reductions or waivers for individuals with low income. You must request this through your probation officer or by filing a motion with the court. Bring documentation of your income and expenses. However, the court is not required to waive fees, and many courts deny requests. You remain responsible for the cost unless the court explicitly orders otherwise.

What happens if I move to a different state while on interlock probation?

You must notify your probation officer and the court before moving. Your original state's probation may be transferred to the new state under interstate compact agreements, and you will need to install an interlock in your new state as well. The requirements and costs may differ. Contact your probation officer for guidance on the transfer process.

Can the interlock device be installed in a rental car or borrowed vehicle?

Smart Start and other vendors can install devices in rental or borrowed vehicles, but the vehicle owner must consent in writing. Rental car companies typically do not allow interlock installation because it requires drilling into the vehicle's electrical system. If you need to rent a car, contact Smart Start to discuss options; some vendors can install temporary devices, but this is not standard practice and may not be available in your area.