Ignition Interlock

An ignition interlock device is a breath alcohol analyzer connected to the ignition of a car. A vehicle equipped with an ignition interlock device cannot be driven unless the driver passes the unit's breath alcohol tests.

Most of these devices work in the following manner:

• When the key is turned a voice prompts the driver to prepare to give a breath test.
• The driver has over 60 seconds to provide a deep lung breath sample--at a pressure rate of 1.5 liters of air given over six seconds--providing the unit with a sample of alveolar air from the bottom of the lungs.
• Testing the sample takes 25 seconds.
• After test completion, a voice either prompts the driver to start the car or lets him/her know it will not start.
• To discourage someone else from providing the original breath sample (a violation of the law when using Model DM-904, the model used when an ignition interlock system is mandated by the court), two "random rolling retests" are given within 20 minutes of starting.
• If a retest is failed a voice instructs the driver to pull over and shut off the car. If this instruction is ignored the horn sounds and the lights blink until the car is shut off.
• The unit's computer records all test and pertinent driving data. This is downloadable and printable. In the case of mandatory use, this data can only be accessed by court officials. Any attempt at tampering with the unit registers in this data log.