What Is An Ignition Interlock Device?

By: Guest
September 11 2020

If you received a drunk driving offense, it’s normal to feel confused and overwhelmed. Likely, you’ll also wonder what the next steps are. If anything, it’s safe to assume one of the most prevalent requirements following a drunk driving offense is an ignition interlock install.

Overview of Ignition Interlock Devices

An ignition interlock device is a handheld breathalyzer that is installed in the vehicle. Ignition interlock devices come in various shapes and sizes. Typically, however, they are about the size of a television remote.

The first ignition interlock device was first introduced in the market in 1988. Since it has proven to be successful in helping minimize drunk driving fatalities, the use of ignition interlock devices has become even more widespread.

There are several ignition interlock device manufacturers in the United States. While each device looks different, they are almost the same size and have the same components.

An ignition interlock device is made up of the following:

    • Handheld unit
    • Mouthpiece
    • Relay cord that connects the device to the vehicle
    • Camera unit (if required by the specific state you are in)

Other Terms for Ignition Interlock Device

While the ignition interlock device is the common name used in the industry, there are other term variations. For instance, the devices are also commonly referred to as “car breathalyzers.” The term makes sense as an ignition device is literally a breathalyzer for your vehicle.

In some instances, an ignition interlock device is also abbreviated as IID. The term is often used on the court and paperwork when you’re required to have the device installed. If not referred to as a car breathalyzer, IID, or ignition interlock device, the device might be referred to as a ‘breath alcohol ignition interlock device’ or BAID.

The term ‘breath alcohol ignition interlock device’ is mostly used in Illinois but not in other states. Homegrown terms like ‘blow n go’ is also used to refer to the device. However, typically, the device is referenced using some of the classic names mentioned earlier.

How Ignition Interlock Devices Work

Primarily, ignition interlock devices are designed to do the following:

  • Prevent an individual from starting their car while intoxicated.
  • Warrant continued sobriety from the driver while behind the wheel and on the road.

Here’s how ignition interlock devices accomplish what they are designed to do:

Preventing an intoxicated driver from starting the vehicle

An individual with an ignition interlock device in their vehicle must provide a breath sample into the device’s mouthpiece before they can start their car. Ignition interlock devices that are state-certified utilize fuel cell technology to measure the amount of alcohol on the user’s breath.

If the breath sample detects alcohol at or above the limit set by the state (typically around 0.02), the vehicle will not start. If the driver’s breath sample returned a breath alcohol concentration (BAC) below the limit set, the driver can insert the key into the ignition and drive the vehicle.

Each of the states has individual ignition interlock device regulations and laws that determine the consequences of a failing breath sample. While some ignition interlock devices allow drivers to continue blowing into the machine until they get a passing breath sample, others can lock drivers out after numerous failed attempts.

Your attorney, ignition interlock provider, or the Motor Vehicle Department (DMV) can give you guidance on how the device works, so there are no surprises.

Continuous Sobriety while Running the Vehicle

Once the vehicle is running, drivers will be required to provide breath samples throughout the trip’s entire duration. This can help ensure the driver is sober before starting the vehicle and throughout the whole trip. These continued tests are referred to as random retests.

In most cases, drivers are given 4-6 minutes to complete a random retest. This helps ensure the driver can pull over to the side if needed or take precautionary measures when driving in heavy traffic.

The Lowdown on Random Retests

Random retests are considered safe and effective. Drivers will hear the device beep when a retest is required. All you need to do is provide a breath sample, and you can continue driving.

If you happen to provide a breath sample with a BAC that’s about the limit set by your state, your car will signal you to pull over and turn the vehicle off. However, specifics can vary from one state to another.

For instance, other states will require that you flash your lights or sound your horn after a failed retest. Unfortunately, no ignition device can turn any vehicle off. Once the car has started, the ignition interlock device won’t be able to turn it off.

How to Gauge if You Need an Ignition Interlock Device

In most cases, you will be informed if you need to install an ignition interlock device through a court order or a monitoring authority in your specific state. This could be:

  • Judge/court
  • Vehicles attorney
  • Probation officer
  • Department of Transportation/Motor

If you are required to have an ignition interlock device installed, you may install the device right away or sit out a required license suspension. As a general rule of thumb, it would be best to check and discuss things with your interlock provider after your conviction or arrest so you can get proper guidance.

Apart from a license suspension, you may also be required to complete other steps before you are considered eligible to install the device. Possible measures can include:

  • Alcohol assessment or treatment program
  • Payment of fines and fees
  • Filling out the interlock application alongside other paperwork

Your monitoring authority or ignition interlock provider can guide you through the entire process and give you advice specific to your location and offense.


For some people, the idea of cheating an ignition interlock device can be so tempting. However, ignition interlock devices have evolved significantly over the years that they have become impossible to trick or circumvent. So if you are considering tampering or cheating with your device, authorities often only have one advice: don’t.

Lauren McDowell is the Content Marketing Strategist for Interlock Install, a Phoenix-based company that performs the installations, service appointments, and removals for ADS Interlock. When not writing, she attends book clubs and enjoys reading stories to her kids.

This is a guest post by Lauren McDowell. This post has been edited for syntax and grammar.  The Law offices of Jay Leiderman is not responsible for the accuracy of the content herein or any opinions or ideas expressed herein.  This post is for entertainment and literary value and is not intended as legal advice.  This post does not establish an attorney-client relationship of any sort.  If you have legal questions about ideas presented herein please contact a lawyer knowledgeable in this field of practice.

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