Even after a person charged with DUI has served a full sentence, some conditions can last longer than jail time. One such condition is the installation of an ignition interlock device (IID), which is a must if the offender was found to have a BAC of 0.15 or greater at the time of the offense.
The IID prevents the driver from starting a car if it detects blood alcohol level that is past a preset limit. The IID system consists of a mouthpiece for the breath test wired onto the ignition system. To start a car, a driver with a DUI offense would have to breathe into a mouthpiece that gauges blood alcohol content (BAC). The default limit is set at 0.04, but installation crews can set it to zero tolerance if the courts of the Department of Motor Vehicles requires it.
The device may not be foolproof as it can be tricked by a hand pump or someone who isn’t drunk. In addition, drivers with IIDs installed on their vehicles are required to conduct “rolling retests” on a regular basis.
In a rolling retest, the IID will require the driver to pass another breath test. This can happen in intervals of between 5 and 30 minutes. The engine may shut down automatically after a failed test, which can be dangerous in the middle of a busy freeway.