What is an Ignition Interlock Device (IID)?


The ignition interlock system is a breathalyzer device installed on the dashboard of a vehicle, often times as required by law following a drunk driving conviction.

This device prevents the driver from starting a vehicle until he or she passes the blood alcohol concentration (BAC) test that is built into the ignition interlock device.

If the breath test reveals that a driver's BAC is above a set limit, usually around .02-.04%, the starter on the car vehicle will lock, preventing the driver from using the vehicle. If a driver's BAC is below that set limit, then the vehicle will start and operate normally.

If you were recently arrested for drunk driving and are worried about having an Ignition Interlock Device installed in your car, talk with a local DUI attorney today:

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When is an IID Issued?

Depending on the state where you reside, you may or may not be required to have an IID installed in your car. A single DUI conviction could result in one of these devices being installed in your car.

If you're forced to have one of these devices installed in your vehicle, you will also be responsible for paying for the installation and monthly usage fees, which may cost you hundreds of dollars.

Each year, the number of states requiring this device be installed in the cars of individuals who receive a drunk driving conviction is increasing.

How Much Does an Ignition Interlock Device Cost?

Rental for an ignition interlock is typically between $100 - $140 a month plus tax. There is also an installation fee, typically around $200.

Maintenance and data downloading for the device are generally additional expenses that must be covered. Under certain conditions, a person may be required to return to the place where they rented the IID to have the records on the device downloaded in order to continue driving.

Court orders for DUI convictions typically require you to pay for your ignition interlock installation, usage and maintenance, which can be purchased or rented from state-authorized private companies.

DUI State Laws and Ignition Interlock

Most states have provisions mandating the use of ignition interlock systems by convicted drunk drivers. DUI laws vary by state, with some requiring a person with a first DUI offense to install the devices as a condition of probation or driver's license reinstatement. The systems are mandatory in most states for drivers with multiple DUI offenses.

More states are requiring an ignition interlock system after a first DUI. The system may be required if the first DUI offense meets certain standards:

Following a DUI conviction, a judge may order you to use an ignition interlock system, often for up to one year. Legal requirements for an ignition interlock device vary according to state.

In some DUI cases, state courts may include ignition interlock as a condition for granting a work license or restricted driver's license. A person with a DUI conviction may be required to rent an ignition interlock in order to maintain or regain driving privileges. Most states require that the driver pay all rental and service fees.

Following a driver's license suspension or revocation from a DUI conviction, states may require a person hold a restricted license for a period of time before regaining full driving privileges. A license placed under restrictions will often require the use of an ignition interlock system.

Voluntary use of an interlock is less common but is becoming increasingly more so, especially in corporate and government sectors. Companies with extensive driving fleets and certain school districts will use ignition interlock systems on company trucks or buses for safety reasons.

Can You Fool an Ignition Interlock?

The manufacturers of ignition interlock systems have built the device in a way that prevents drivers from tampering with it. The interlock device is programmed to lock a vehicle and report any actions attempting to:

  • Use another person or mechanical device to blow into the machine
  • Refuse to submit a test
  • Tamper with the device

Some brands of interlock devices require the driver to suck in air or make a humming noise while blowing through the breathalyzer, tasks that a machine could not duplicate. Some of the newer devices even take a picture of the person blowing into the machine.

The random tests while driving make it impossible to have a sober friend take the test before the car will start. If a person refuses to take one of the random tests, the headlights and taillights will flash and horn will sound obnoxiously until he or she pulls over to perform the breathalyzer test. If the device is tampered with, it will lock out the ignition and record the incident in its database, which will downloaded by the supplier and turned over to the court.

If you are facing additional charges or penalties due to your drunk driving or ignition interlock violations, find out about your rights during a free DUI consultation with a local lawyer. Complete the free form on this page to connect right away.

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