Ignition interlock device
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An ignition interlock device or breath alcohol ignition interlock device (IID and BAIID) is a mechanism, like a breathalyzer, installed on a motor vehicle's dashboard. Before the vehicle's motor can be started, the driver first must exhale into the device; if the resultant breath-alcohol concentration analyzed result is greater than the programmed blood alcohol concentration (which varies between countries), the device prevents the engine from being started.
At random times after the engine has been started, the IID will require another breath sample. The purpose of this is to prevent someone other than the driver from providing a breath sample. If the breath sample isn't provided, or the sample exceeds the ignition interlock's preset blood alcohol level, the device will log the event, warn the driver and then start up an alarm (e.g., lights flashing, horn honking) until the ignition is turned off, or a clean breath sample has been provided. A common misconception is that interlock devices will simply turn off the engine if alcohol is detected; this would, however, create an unsafe driving situation and expose interlock manufacturers to considerable liability.
Modern ignition interlock devices use an ethanol-specific fuel cell for a sensor. A fuel cell sensor is an electrochemical device in which alcohol undergoes a chemical oxidation reaction at a catalytic electrode surface (platinum) to generate an electric current. This current is then measured and converted to an alcohol equivalent reading. Although fuel cell technology is not as accurate or reliable as infrared spectroscopy technology used in evidentiary breathalyzers, they are cheaper and tend to be more specific for alcohol.
The devices keep a record of the activity on the device and the interlocked vehicle's electrical system. This record, or log, is printed out or downloaded each time the device's sensors are calibrated, commonly at 30, 60, or 90-day intervals. Authorities may require periodic review of the log. If violations are detected, then additional sanctions can be implemented.
Periodic calibration is performed using either a pressurized alcohol–gas mixture at a known alcohol concentration, or with an alcohol wet bath arrangement that contains a known alcohol solution. The costs of installation, maintenance and calibration are generally paid by the offender, and typically are about $75 per month.
Many countries are requiring the ignition interlock as a condition for drivers convicted of driving under the influence, especially repeat offenders. Most U.S. states now permit judges to order the installation of an IID as a condition of probation; for repeat offenders, and for first offenders in some states, installation may be mandated by law. MADD have campaigned for mandatory IID installation for all first offenders. Some politicians in Sweden, Japan, Canada, the U.S. and other countries have called for such devices to be installed as standard equipment in all motor vehicles sold.
If driving on a suspended license due to a DUI conviction, legally the court must impose an ignition interlock device requirement for up to a maximum of three years from the date of conviction. As of July 1, 2010 interlocks are required upon a DUI conviction in four counties; Los Angeles, Alameda, Sacramento and Tulare. -AB 91 creates a pilot program for select counties, such as Los Angeles County, that will require all drivers convicted of a DUI offense to install IIDs in their vehicles as a condition to receive restricted driving privileges. -SB 598 shortens the amount of time certain repeat DUI offenders will have to wait before becoming eligible to apply for restricted California driving privileges. To receive the restricted license though, these drivers will be required to meet certain criteria, such as the installation of an IID in their vehicles.
Upon conviction of a second DUI, the violator's license is suspended for no less than 18 months. During the final six months of this suspension the driver in question is required to have a working ignition interlock device installed in any vehicle that he or she intends to operate.
Starting January 1, 2006, drivers that had a second or subsequent operating under the influence offense and are eligible for a hardship license or for license reinstatement, are required to have an ignition interlock device attached to their motor vehicle, at their own expense.
New Mexico 
Ignition interlocks are required for at least one year for all first-time DWI offenders; subsequent offenses require longer periods of installation.
New York 
As of August 15, 2010, New York state requires a person sentenced for Driving While Intoxicated have an ignition interlock device installed for at least 6 months on any vehicle they own or operate, and the driver have an "ignition interlock" restriction added to their driver license.
North Carolina 
A conviction of Driving While Impaired with a blood alcohol concentration of 0.15 or more or another conviction within the past seven years will require an ignition interlock device to be installed on the vehicle.
Effective July 2, 2009, anyone convicted of a DUI, whether it be a first offense or a subsequent offense, will be required to have an ignition interlock device placed on their car — for 18 months for first time offense.
Effective July 1, 2012, anyone who is convicted of DUI may drive only with an ignition interlock after the first offense, as a condition of a restricted license and is required to have an ignition interlock installed in each vehicle owned by or registered to him after a second offense. The bill also provides that the court may authorize a restricted license for travel to and from the interlock installer and a person can pre-qualify for an ignition interlock prior to conviction.
New Zealand 
Alcohol interlock devices became a sentencing option in New Zealand in August 2012. In December 2012, it was reported that the first device has been installed.
- "Interlocking Thresholds". thebuilderssupply.com. Retrieved 12 April 2013.
- Sverige trycker på EU om obligatoriskt alkolås (Swedish)
- Motion om alkolås (Swedish)
- Cordell, LaDoris (2009-09-22). "Baby, You Can't Drive Your Car: A judge's favorite punishment for drunken drivers—ignition-interlock.". Slate.
- State of, Arizona. "Arizona Interlock Laws". Ignition Interlock. Arizona MVD. Retrieved 27 September 2012.
- California DUI Vehicle Code Sec. 14601.2
- Massachusetts Driver's Manual, pp. 56–57
- "New York State Department of Motor Vehicles - NYS DMV - NYSDMV - Driver - Vehicle". Nydmv.state.ny.us. Retrieved 2012-07-15.
- North Carolina Driver's Manual, p. 29
- "Utah Code". Le.state.ut.us. Retrieved 2012-07-15.
- "LIS > Bill Tracking > HB279 > 2012 session". Lis.virginia.gov. Retrieved 2012-07-15.
- Maas, Amy (30 December 2012). "Six beer habit earns first interlock". The Press. Retrieved 30 December 2012.