What Is an Ignition Interlock Device (IID)?

A breath alcohol ignition interlock device (IID), or ignition interlock system, is a mechanism like a breathalyzer that tests for alcohol on a driver's breath. An IID, however, is installed in a vehicle to require a driver to breathe into the device before the vehicle can be started. If the driver's breath alcohol concentration (BAC) is over the programmed limit (typically .02% to .04%) the vehicle's ignition is disabled and the vehicle will not start.

The U.S. Government's National Highway Traffic Safety Administration (NHTSA) maintains a " Conforming Products List" (PDF download) of breath alcohol devices approved for law enforcement use. Interlocks that meet the NHTSA standards not only require a test to start the engine, but also require a test every few minutes while driving - a "rolling or running retest." This type of test prevents an individual other than the driver from starting the car and then allowing an impaired driver to drive the vehicle. (NHTSA guidelines for most regions call for only one subsequent test). Ignition interlocks can be difficult to circumvent when properly installed and monitored regularly.

The amount of time an individual is required to have ignition interlock on his or her car varies based on prior offenses and other restrictions. See which states require ignition interlocks.

Steps for using an Ignition Interlock:

• Get in car and put on seatbelt.
• Push button on Ignition Interlock.
• Wait for confirmation messages to appear.
• Blow into mouthpiece.
• Wait for "pass" (or "fail") confirmation messages to appear.
• If "pass", place keys in ignition and start vehicle.

Also See:

• What is a Breathalyzer?
• DUI Punishments and Consequences

Related Libraries:

• Blood Alcohol Concentration (BAC)
• Drunk Driving Prevention
• Legal

Related Links:

• State DUI Information
• DUI Lawyers
• SR-22 Auto Insurance Quote
• Criminal and DMV Records