An ignition interlock device (IID) is a breath testing mechanism placed into your vehicle that requires a clean sample of your breath in order to set the vehicle in motion.  The IID is installed in the ignition system of your car, and is able to detect levels of alcohol present in a person's system. A breath sample must be provided to start the car, and random samples must be given to keep the car moving.  (This is to prevent a sober friend from starting the car for an intoxicated person).  The machine is calibrated so that any breath result over a .02 percent will render the car immobile.

A breath sample above .02 will set off warning noises and eventually stop the vehicle altogether.  Enough time and notice is given to the driver so that he or she may pull safely off the roadway.  The interlock device records and stores all sample information, and the IID company will review and relay results over .02 to the proper authorities.  Violations of ignition interlock requirements will result in additional sanctions issued by the court.  Additional jail time and fees are likely to be imposed.

Every person convicted of a first offense DUI in Washington State must install an IID in their vehicle for a mandatory one year period.  A second offense DUI conviction results with a mandatory five year period of ignition interlock.  For third offenses, the IID will be in place for 10 years.

IID devices are costly.  They typically require an initial activation and installation payment of anywhere from $50 - $100, plus a similar monthly fee.