Breath Alcohol Ignition Interlock Devices

This device is a popular, effective and relatively inexpensive mechanism for allowing the hardcore offender to drive legally. The purpose is to prevent a person who has consumed alcohol from driving a vehicle. The device measures alcohol concentration in the breath and is attached to a vehicle’s ignition system. The driver must blow into the device before the car can be started. If the BAC level is above the predetermined level, the vehicle can’t be started.

Most of the devices have a number of anti-circumvention features, including a data recorder, which documents all vehicle uses as well any attempt to tamper with the device, and a rolling retest feature, which requires the driver, after starting the vehicle, to supply at least one other breath sample. This feature helps prevent circumvention of the interlock by having someone else provide the initial breath sample.

Where Are Breath Alcohol Ignition Interlock Devices Used?

At least 41 states, the District of Columbia and Puerto Rico have either mandatory or discretionary interlock laws. Eight (Beirness 2001) different device manufacturers are marketing BAIIDs in states with enabling legislation, and about 30,000 (Voas et al. 2002) devices are installed in the United States and Canada. West Virginia and Maryland are the only states where the DMV controls and administers the ignition interlock program, which is voluntary and incentive-based for eligible offenders. To be eligible, offenders must be enrolled in, or have completed, a safety and treatment program.

How Effective Are Breath Alcohol Ignition Interlock Devices?

These devices can significantly reduce recidivism, at least while the restriction is in place. A 1999 meta-analysis of research on DWI recidivism while interlocks were installed found offenders with interlocks were 15–69 percent less likely to be re-arrested for DWI than those without interlocks (Coben and Larkin 1999). After 12 months of use, interlock users were 16 times less likely to recidivate than non-interlock offenders (Marques et al. 2001). Once interlocks are removed, recidivism rates are generally comparable between interlock participants and non-participants, although an Alberta study has shown the five-year re-offense rate for repeat offenders on interlocks was half that of those not using interlocks (Beirness 2001).

Research has also shown 60 percent of repeat offenders can be predicted by the number of repeat DWI offenses and the number of ignition interlock breath test failures and warnings. This research suggests using breath test records obtained from the interlock’s data logging system recorder could help to further identify those likely to recidivate once the interlock is removed. A longer period of interlock use would be appropriate for these offenders (Marques et al. 2001).

"Attempting to start an interlock-equipped vehicle on more than a couple of occasions with a BAC of at least 0.08 percent is a discrete and reasonably good predictor of repeat offenses" (Marques et al. 2001).

In addition to the reduction in recidivism, a study by Dussault and Gendreau (2000) found a 60 percent reduction in injury and property damage crashes during and after interlocks were installed in offenders’ vehicles in Quebec, Canada.

Interlocks as part of a comprehensive system. Studies recommend interlocks be part of an integrated program aimed at offender rehabilitation and not thought of merely as a device installed in an offender’s vehicle. Research indicates they can substantially reinforce the effectiveness of alcohol treatment and should be required during the entire treatment and follow-up period. In Calgary, case managers were available to meet with interlock clients during their regular visits to the service center to help prevent a relapse after the interlock was removed.

Drivers at the Calgary intervention site were regularly interviewed about their drinking and driving choices and educated on how to better plan their drinking choices so they would not coincide with driving. Interlock participants were also offered supportive counseling and service referrals along with the motivational support. A study by Marques, Voas, Tippets and Beirness in 2000 found interlock participants in cities offering this type of intervention had a lower rate of failed interlock breath tests than participants in cities without intervention.

"A comprehensive interlock program should emphasize the beneficial, rehabilitative aspects of the program over its punitive and deterrent aspects. Although it may be difficult for participants not to view the program as punitive, every effort should be made to help participants understand the goal of the program is to prevent subsequent drinking-driving problems and have them become fully reinstated licensed drivers with little risk of recidivism" (Beirness 2001).

This system is not foolproof. It obviously does not keep offenders from operating other vehicles not fitted with interlock devices, such as rental cars. There is some evidence the devices can be circumvented, but technological improvements, such as the rolling re-test, have greatly reduced this possibility.

It is important to note research doesn’t recommend the use of ignition interlocks as a substitute for licensing sanctions but rather as a condition of licensing reinstatement after a period of suspension.

How Much Do Breath Alcohol Ignition Interlock Devices Cost?

The cost of the program is usually paid for by the offender. The national average cost to rent the equipment is about $60 a month. In West Virginia, there is a $25 application fee and the device costs approximately $105.

Where to Go for More Information on Breath Alcohol Ignition Interlock Devices

Beirness, D.J. 2001. Best Practices for Alcohol Interlock Programs. Ottawa, Canada: Traffic Injury Research Foundation. www.trafficinjuryresearch.com.

Coben, J.H., and Larkin, G.L. 1999. Effectiveness of ignition interlock devices in drunk driving recidivism. American Journal of Preventive Medicine 16.

Dussault, C., and Gendreau, M. 2000. Alcohol ignition interlock: One-year’s experience in Quebec. Proceedings of the Fifteenth International Conference on Alcohol, Drugs, and Traffic Safety, Stockholm, Sweden.

Voas, R.B., Blackman, K.O., Tippetts, A.S., and Marques, P.R. 2002. Evaluation of a program to motivate impaired driving offenders to install ignition interlocks. Accident Analysis & Prevention 34(4): 449–455.

Marques, P.R. et al. 2001. Predicting repeat DUI offenses with the alcohol interlock recorder. Accident Analysis and Prevention 33(5): 600–619.

Tippetts, A.S., and Voas, R.B. 1996. The Effectiveness of the West Virginia Interlock Program. Bethesda, MD: The Pacific Institute.