Year-after-year state legislatures try to find ways to curb drunk driving. In this search, an increasing number of states are imposing ignition interlock device (IID) requirements—or making existing IID laws stricter—for those convicted of driving under the influence (DUI). Basically, IIDs are breath-test devices that are installed in a vehicle, which prevent it from starting when the driver has a measurable breath alcohol concentration (BAC).
IIDs are essentially breathalyzers that attach to a car's ignition system. Generally, IID must be installed by a company that's authorized by state law to do so. The main functions of an IID are to prevent a person from starting a vehicle if he or she has been drinking alcohol and notify the court, DMV, or the probation department when a driver tries to drive after consuming alcohol.
A car that has an IID installed won't start until someone blows into a tube with an alcohol-free breath. One of the weaknesses of IIDs is that they can't distinguish between different people. So, it's entirely possible for an intoxicated driver to get someone else (who hasn't been drinking) to blow into the IID before starting the car. Sidestepping an IID in this way is generally illegal for the driver and the person who assists, but people still do it sometimes.
Most IIDs also require "rolling tests" every so often after the car is started. Typically, the IID will beep—indicating a rolling test is necessary—and the motorists has about five minutes to give a breath. This delay time gives time to pull over and park before breathing into the device.
If an IID detects alcohol on a rolling sample, it won't shut the car off. But the device will record the positive result and likely notify the court, DMV, or probation department.
All 50 states have IID legislation. But IID laws aren't all the same. There are laws that:
In recent years, most states have moved in the direction of requiring IIDs in more cases.
When IIDs are required, it's typically up to the motorist to pay the costs. Costs normally include installation, removal, and monthly fees. Although expensive (installation and removal might cost $100 to $300 total and monthly fees can be $50 to $100), most people prefer paying the fees to have an IID rather than forgo driving.
In many states, it's possible for someone whose license has been suspended for a DUI to get a "hardship" license (also called a "Cinderella" or "restricted" license). Generally, hardships licenses allow the motorist—whose license is otherwise suspended—to drive to and from places like work, school, and medical appointments. Having an IID installed is a common prerequisite for obtaining a hardship license.
If you have specific questions about the IID or DUI laws in your state, it's always best to talk to a local DUI attorney. The facts of each case are different. A qualified DUI lawyer can tell you how the law applies in your particular situation.