The ignition interlock devices (IIDs) mounted in the dashboards of the vehicles of Galveston, TX DWI offenders are like the drivers’ own personal breathalyzers. Before the IID will allow a driver to start the car, he or she must provide a breath sample to the IID. If the IID analysis finds a breath alcohol concentration higher than the programmed concentration (generally .02% to .04%), the IID won’t let the driver start the car.

If the driver passes the initial breath sample test and the IID starts up the motor, then at various times during the following drive, the IID requires further breath samples. This continuing sample requirement intends to prevent the convicted Galveston DWI offender from using a sober friend to breathe into the IID to start the car. The purpose of the IID is to prevent convicted DWI offenders from getting behind the wheel drunk again and causing additional accidents, injuries, or fatalities.

If the additional breath samples aren’t given, or they exceed the programmed alcohol concentration, the IID creates a log entry of the discrepancy, warns the driver, and then engages an alarm system that continues until the car’s turned off or a clean breath sample is given. The alarm might include honking the horn and flashing the lights. The log entry and alarm notify authorities that a convicted DWI offender might be DWI again.

The IID utilizes an ethanol-specific fuel cell sensor. In this cell, alcohol experiences chemical oxidation at a catalytic electrode surface to generate electrical current. The current is measured and analyzed to determine the amount of alcohol that generated that amount of current.

IIDs record breath sample frequency and results in a log. The log can be printed out or downloaded for information. The download occurs each time the IID sensors receive calibration. Calibration intervals might be monthly or every 60 days or 90 days. Authorities review the log periodically, and if violations are found, then further DWI penalties might ensue. Installation, maintenance, and calibration costs for the IID typically get charged to the DWI offender.