Ignition interlock device

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An ignition interlock device or breath alcohol ignition interlock device (IID and BAIID) is a breathalyzer for an individual's vehicle. It requires the driver to blow into a mouthpiece on the device before starting the vehicle. 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.[1]

An ignition interlock interrupts the signal from the ignition to the starter until a valid breath sample is provided that meets minimal alcohol guidelines in that state. At that point, the vehicle can be started as normal. 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.


The first performance based interlocks were developed by Borg-Warner Corp. (now BorgWarner, Inc.), in 1969. In 1981, Jeffrey Feit, a student in New Jersey, placed in a statewide innovation contest with a primitive schematic of a breathalyzer based interlock device. in 1983, Hans Doran, a student in Limerick, presented a working prototype at the Young Scientist competition in Dublin. Alcohol-sensing devices became the standard through the 1980s. They employed semiconductor (nonspecific) alcohol sensors. Semiconductor-type (Taguchi) interlocks were sturdy and got the field moving, but did not hold calibration very well, were sensitive to altitude variation and reacted positively to non-alcohol sources. Commercialization and more widespread adoption of the device was delayed pending improvement of systems for preventing circumvention. By the early 1990s, the industry began to produce “second generation” interlocks with reliable and accurate fuel cell sensors.


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. On average, ignition interlock devices are about $70–150 to install and about $60–80 per month for monitoring and calibration.[2]

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. Mothers Against Drunk Driving have campaigned for mandatory IID installation for all first offenders. Some politicians in Sweden,[3] Japan, Canada, the U.S., and other countries have called for such devices to be installed as standard equipment in all motor vehicles sold.[citation needed]



As of 2012, all 50 states have laws permitting the imposition of ignition-interlock devices as sentencing alternatives for drunken drivers.[4]


Arizona mandates at least six months for all DUI offenses, even those not involving alcohol.[5]


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.[6]


Upon conviction of a second DUI within a 5-year period, the violator's license is suspended for no less than 18 months. See O.C.G.A. 40-5-63(a)(2). During the first 120 days of the 18-month suspension, the violator has no limited driving privileges. See 40-5-64(a)(2). Following the 120-day hard suspension, the violator may apply for a 12-month interlock permit, upon the approval by an accountability court or proof of enrollment in a state-licensed substance abuse treatment program. O.C.G.A. 40-5-64(a)(2). During the final two months of the 18-month suspension, the driver in question can have the interlock restriction removed from their limited permit. O.C.G.A. 40-5-64(e)(2). The sentencing court can waive the interlock requirement in cases of financial hardship, but the violator still must serve the 12-month period designated for interlock under a hard suspension. See O.C.G.A. 42-8-111.[7]


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.[8]

New Mexico[edit]

Ignition interlocks are required for at least one year for all first-time DWI offenders; subsequent offenses require longer periods of installation.[9]

New York[edit]

Don Prudente from DriveSafe Ignition Interlock of New York, Inc. states that 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.[10] This was mandated in honor is Leandra Rosado who died riding in a vehicle driven by a drunk driver.

North Carolina[edit]

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.[11]


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.[12]


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 for a period of six months. 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.[13]


First-time DUI convictions result in one year of a mandatory ignition interlock device.[14] A second conviction requires the IID be installed for at least five years, and on a third offense or greater, the requirement becomes at least ten years. Some convictions of negligent driving or reckless driving can require the convicted person to use an IID for a period of six months or longer.

New Zealand[edit]

Alcohol interlock devices became a sentencing option in New Zealand in August 2012. In December 2012, it was reported that the first device had been installed.[15]


Some provinces, such as Ontario[16] and Quebec,[17] require any person convicted of drunk driving or refusing to provide a breath example, to install an ignition interlock device into any vehicle he or she owns or operates, for a specified period of time (or for life), depending on the number of prior drunk driving offenses.

After so many drunk driving convictions, some provinces, such as Nova Scotia,[18] will impose a lifetime driving ban, with no possibility of license reinstatement. Ontario[19] courts, however, have the power to enact lifetime driving bans, with no possibility of reinstatement, after so many Criminal Code driving convictions. Under such circumstances, ignition interlock conditions are not put in place on the person's license.


  1. ^ http://criminallawyermaryland.net/dui/maryland-ignition-interlock-lawyer.html#wiki
  2. ^ "Ignition Interlock FAQ's". 
  3. ^ Motion om alkolås (Swedish)
  4. ^ Cordell, LaDoris (2009-09-22). "Baby, You Can't Drive Your Car: A judge's favorite punishment for drunken drivers—ignition-interlock.". Slate. 
  5. ^ State of, Arizona. "Arizona Interlock Laws". Ignition Interlock. Arizona MVD. Retrieved 27 September 2012. 
  6. ^ "Section 14601.2". State of California 2013 Vehicle Code (PDF). Sacramento: Department of Motor Vehicles. 2013. 
  7. ^ 2013 Driver's Manual (PDF). Georgia Department of Driver Services. 2013. 
  8. ^ Massachusetts Driver's Manual, pp. 58
  9. ^ "The High Cost of DWI in New Mexico" (PDF). University of New Mexico. 2010. Retrieved 30 October 2013. 
  10. ^ "Alcohol and Drug Driving Violations". New York State Department of Motor Vehicles. Retrieved 2012-07-15. 
  11. ^ North Carolina Driver's Manual, p. 29
  12. ^ "Utah Code". Le.state.ut.us. Retrieved 2012-07-15. 
  13. ^ "HB 279 DUI ignition interlock; required on first offense as a condition of a restricted license.". Virginia's Legislative Information System. Retrieved 2012-07-15. 
  14. ^ "WA State Licensing (DOL) Official Site: Ignition interlock device". Washington State Department of Licensing. Retrieved 2015-01-24. 
  15. ^ Maas, Amy (30 December 2012). "Six beer habit earns first interlock". The Press. Retrieved 30 December 2012. 
  16. ^ http://www.mto.gov.on.ca/english/safety/impaired/interlock.shtml
  17. ^ http://www.saaq.gouv.qc.ca/publications/permis/condition_x_en.pdf
  18. ^ http://www.novascotia.ca/snsmr/rmv/safe/alcohol.asp
  19. ^ http://www.mto.gov.on.ca/english/dandv/driver/handbook/section4.8.10.shtml