Ignition Interlock Devices: Costs and Requirements

Basics about how ignition interlock devices (IIDs) work, when they’re required, and how much you’ll have to pay for one.

By , Attorney · University of San Francisco School of Law

The DUI laws in lots of states require offenders to install ignition interlock devices (IIDs) in their vehicles. It's also common for an IID to be a requirement for obtaining a restricted license, which allows a motorist to drive during a DUI suspension period.

This article covers the basics of ignition interlock devices, including how they work, when they're required, and the costs to the driver.

What Is an Ignition Interlock Device?

An ignition interlock device is a breath-test machine ("breathalyzer") that's connected to a vehicle's ignition system. Once an IID is installed, the vehicle won't start until someone breathes into the IID with an alcohol-free breath.

The idea, of course, is to prevent someone who's been drinking from driving the vehicle.

When Are Ignition Interlock Devices Required?

Most, if not all, states have DUI laws that incorporate ignition interlock devices in one way or another. However, the specifics of ignition interlock laws and requirements differ quite a bit by state. Below, we discuss some of the more common types of IID laws.

Ignition Interlock Requirements for DUI Convictions

Generally, a DUI conviction leads to at least some period of license suspension or revocation. Lots of states now require convicted motorists to install an ignition interlock as a condition of license reinstatement. However, the specifics of these types of laws differ by state.

Some states require IIDs for all DUI offenders, including those convicted of a first DUI. Other states mandate IIDs only for repeat offenders or offenders with high blood alcohol concentrations (BACs). And a number of states let judges decide, based on the circumstances of each case, whether to order an IID.

Installing an Ignition Interlock as a Condition for Getting a Restricted License

Although license suspension is likely to result from a DUI conviction, many states allow suspended drivers to apply for what's called a "restricted" or "hardship" license. This type of license gives a person at least limited driving privileges during a DUI suspension.

It's common for states to require an ignition interlock device as a condition for obtaining a hardship or restricted license.

How Long Will I Need an Ignition Interlock?

The length of an ignition interlock requirements depends on a number of factors.

When a driver is required to use an ignition interlock as a condition of license reinstatement (following a DUI conviction), it's common for the length of IID requirements to increase with the number of prior convictions. In other words, the period of time an offender would be required to maintain an IID for a first offense would be less than it would be for a second offense, and so on. For example, a first DUI might come with a six-month IID requirement, whereas someone convicted of a third DUI could be required to have an IID for several years.

The length of an IID requirement might also depend on whether the offense involved aggravating factors. For example, having a high BAC could increase the period of time the driver must have an IID.

When a driver installs an IID to obtain a restricted license, on the other hand, the requirement might last only the duration of the restricted license. In other words, the IID requirement might end once the motorist's full driving privileges are reinstated.

How Much Do Ignition Interlock Devices Cost?

IIDs aren't cheap. And it's usually up to the driver to pay the costs. But for most people, the expense is preferable to not driving.

The costs of an IID can generally be broken into three parts:

  • Installation fee. The cost of getting an IID installed in your vehicle typically ranges from about $50 to $150, depending on where you get it installed and the make of your vehicle.
  • Monthly fees. A motorist can usually expect to pay about $50 to $150 total for monthly IID monitoring, maintenance, and lease fees.
  • Removal fee. When it's time to take the IID out of your car, you'll generally need to pay a removal fee. This may run you anywhere from about $50 to $150.

Some states provide financial assistance to people who are indigent and can't afford IID costs. And IID companies sometimes offer flexible payment plans.

Can a Driver Disconnect or Trick an IID?

IIDs are installed in a way that prevents the driver from simply disconnecting them. And attempting to do so may result in damage to the IID or your vehicle.

However, IIDs have no way of identifying who provides the alcohol-free breath. So it's possible to trick an IID by having someone else blow into it. But IIDs normally require "rolling" samples every so often after the vehicle is started. Though a positive test on a rolling sample won't normally shut down the vehicle, the IID will record the result and the court and DMV will likely find out about it.

Plus, drivers who are caught tampering with or trying to evade an IID will likely face revocation of driving privileges and possibly criminal charges.

Talk to a DUI Attorney

If you've been arrested for driving under the influence, you should get in contact with a qualified DUI lawyer in your area. An experienced DUI attorney can tell you how the law applies in your case, including the requirements and options related to ignition interlock devices.

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