Ignition interlock device
An ignition interlock device or breath alcohol ignition interlock device is a breathalyzer for an individual's vehicle. It requires the driver to blow into a mouthpiece on the device before starting or continuing to operate the vehicle. If the resultant breath-alcohol concentration analyzed result is greater than the programmed blood alcohol concentration, the device prevents the engine from being started. The interlock device is located inside the vehicle, near the driver’s seat, and is directly connected to the engine’s ignition system. It is a form of electronic monitoring.
An ignition interlock interrupts the signal from the ignition to the starter until a valid breath sample is provided that meets maximal alcohol guidelines in that jurisdiction. At that point, the vehicle can be started as normal. A breath sample is not required to start the vehicle if the engine has been running within a time-out period, to allow quick re-starts in case the vehicle stalls. At random times after the engine has been started, the IID will require another breath sample, referred to as a rolling retest. The purpose of the rolling retest 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 in accordance to state regulations 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.
History
The first performance based interlocks were developed by Borg-Warner Corp., 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 alcohol sensors. Semiconductor-type 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. In the US, ignition interlocks are required to meet National Highway Traffic Safety Administration standards.
Design
Modern ignition interlock devices use an alcohol-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 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. Alcohol, as defined here, includes isopropanol, sorbitol, menthol, methanol, and a host of other types of alcohols, in addition to ethanol, the consumed liquor.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.
Some IIDs are equipped with cameras, which may be required by the jurisdiction or voluntarily used. The purpose of the camera is to identify "fail" results with the driver, which conveniently makes it easier to "clear" test failure reports when the "fail" result was triggered by a third party.
Costs
The costs of installation, maintenance, and calibration are generally paid by the offender. Costs vary considerably around the world:As of 2015 in the US, on average, ignition interlock devices cost about $70–150 to install and about $60–90 per month for monitoring and calibration.
Adoption
Many countries are requiring the ignition interlock as a condition for drivers convicted of drunk driving, especially repeat offenders. Most US 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.Some commercial and public organizations have also voluntarily adopted ignition interlock devices for their vehicle fleet, to reduce the risk of monetary and reputational damages from accidents caused by a drunk driving employee.
Oceania
Australia
Interlock devices are used in the states of Victoria, South Australia, Western Australia, Tasmania, New South Wales, and Queensland. The Northern Territory and the ACT are also looking into their use.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 had been installed.Europe
Austria
For a pilot project trialling interlocks from 2012-2013 driving licence administration authorities and a coordinating institution “ABS Institution” were created. Offenders could volunteer only if they met criteria such as "no alcohol addiction", a suspension of the drivers licence for at least four months where at least half of the suspension period had passed etc. The driver had to meet a mentor every two months with examination of data readout for violations and Discussion of the participant‘s experience with the device andof the driving behaviour in reference to the data readout and driver‘s logbook and development of strategies for a successful continuation
of the programme, but no mandatory medical or psychological examination. Costs were 2,500 euros/year for the device, 300 euros to install and remove it and 600 euros minimum for the mentoring programme.
Interlock systems were introduced in 2017 and consolidated into federal law. As of 2020 there was no official evaluation and no published participation rate.
Belgium
Laws permitting judges to impose the use of interlock devices on convicted drunk drivers permitted their use from 2010, however by 2016 it had only been used in 55 cases. The cost, €3,500 to be paid by the driver, is a deterrent to its use. From 2017 the device may be paid from the fines imposed on the driver and in addition it may become compulsory for repeat offenders.Denmark
The Danish Road Safety Traffic Authority trialed the lock in 2015 in a voluntary program, which could replace a licence suspension of maximum two years. As there was a very poor uptake of only 24 drivers, they changed it in 2017 to a three-year programme which resulted in an improved participation rate of 450 drivers as of 2020.Finland
In Finland, the Finnish Transport and Communications Agency first trialled interlocks in 2005. It was put into legal effect in 2008 with a requirement to meet a health care professional for rehabilitation. Installation cost around €2400 for one year, €1920 per year for two years, or €1440 per year for three years. Only 5.7% of the drivers re-offended instead of 30% without the program. As of 2020, there were about 1,000 drivers participating in the Ignition Interlock Device program.France
In France, the interlock programme has included a mandatory addiction consultation. In 2018, an alcohol interlock in repeat offences became compulsory and a trial was extended to the entire country. 1,500 ignition interlock devices were installed from 2018-2020 of a total of 8,104 prefectoral decrees restricting driving. Purchase costs were 1,300 euros or rental at 100 euros/month plus installation fees. The French Prefectures publish a Map of approved alcohol interlocks installers by department and region.Italy
In 2024, Italy implemented mandatory ignition interlock devices as part of its revised Codice della Strada. This regulation requires individuals with prior convictions for driving under the influence to install the device in their vehicles. The measure aligns with EU safety goals and ensures that repeat offenders cannot operate their vehicles while impaired. The costs of installation and maintenance are borne by the offenders themselves, emphasizing accountability. Additionally, there is growing attention to extending the requirement to new vehicles to enhance road safety, aligning with broader European directives, though specific mandates for all new cars are still under discussion.Lithuania
As of 2020, since 2016, more than 80 new school buses equipped with interlock devices had been handed over to municipalities, and 400 drivers had participated in an interlock programme.The Ministry of Health intended to create a new rehabilitation programme for drunk drivers.Netherlands
From December 2011 the Netherlands started to use an interlock device for offenders who were caught with a blood alcohol level over a certain limit. The process which had over 5,000 participants was cancelled in 2015 due to legal and technical problems.Poland
In Poland, since 2015 offenders driving with a BAC above 0.5 g/l may ask the court for their driving ban to be replaced with an alcohol interlock after at least half of the driving ban period has passed. Offenders with a lifetime driving ban can apply for an alcohol interlock after a minimum of 10 years. Interlocks are not part of a rehabilitation programme. The actual number of installed alcoholinterlocks is unknown; the number of court orders were 609 in 2017, 2,180 in 2018, and 840 in the 1st half of 2019.