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Program Profile

Maryland Ignition Interlock Program

Evidence Rating: Effective - More than one study Effective - More than one study

Program Description

Program Goals/Target Population
Maryland introduced the Ignition Interlock Program for drivers with multiple alcohol offenses to decrease the number of subsequent alcohol-related traffic violations. Breath analyze ignition interlock devices have become popular across the Nation as one way to combat alcohol-related vehicular accidents. As of April 2009, 47 States and the District of Columbia had introduced the use of interlock programs (Rauch et al. 2011).

The program targeted drivers applying for license reinstatements who had two or more alcohol-related traffic violations in their lifetime and who had been approved by the Medical Advisory Board in Maryland to apply for the reinstatement. (The Medical Advisory Board is a group of physicians who evaluate certain medical disabilities in motorists requesting license reinstatements.) As currently structured, the program may also be required for drivers who violate a previously imposed alcohol-related driving restriction.

Program Components
Participating drivers were notified by letter that they were eligible for license reinstatement pending enrollment in the program. Participants had 30 days to install the interlock in their vehicle or face suspension for failure to comply. The interlock is a device that connects the vehicle’s ignition system to a breath analyzer. Before the offender can start the car, the individual must breathe into the device, which is calibrated to “lock” the ignition if the breath–alcohol level exceeds a preprogrammed level. The devices are also programmed for “rolling retests” at intervals while the car is in operation. A “datalogger” device captures vehicle usage and records instances of noncompliance. Participants who had no access to a vehicle in which an interlock could be installed could apply for an interlock waiver.

All drivers received a restricted license that barred them from legally operating a vehicle that did not have an ignition interlock installed. All drivers in the program were barred from operating any motor vehicle if they had any alcohol in their system.

Currently, Maryland requires participants to return to the installing vendor every 30 days. The vendor checks the equipment and forwards the information captured by the device to the Motor Vehicle Administration. The report includes information on:

  • The driver, his/her vehicle, and other program information
  • Any instances where the driver had a high blood-alcohol concentration
  • Any instances where the driver tried to start the vehicle without taking the test
  • Any instances where the driver failed the rolling retest or refused to take it
  • Any bypass of the device, which is if the driver tampered with or disconnected the device
  • The number of times the vehicle was started and stopped
  • The distance traveled by the vehicle
A driver’s sentence to drive with an ignition interlock may be extended if one or more violations are detected during a monitoring period. If a violation is detected, the violator receives a letter of notification, and the time in the program is extended by 1 month. The driver may be forced to leave the program and see the original suspension imposed if  there are four monitoring periods with a violation. Drivers are expected to have at least 50 starts within each 30-day monitoring period; if they make alternate arrangements for transportation (e.g., carpooling or using public transportation), they must provide a written explanation for a low number of starts.

Participating drivers are expected to pay for all costs associated with the program, including the installation of the ignition interlock, the monthly maintenance costs, the extra fee for obtaining a restricted driver’s license, and the fee for obtaining a license without the restriction once the sentence has been completed.

Program Theory
To the extent that a theory grounds the use of interlock devices, routine activity theory may apply. This theory predicts that crime increases when motivated offenders find suitable targets that lack capable guardians. The interlock device in this perspective acts as a way to remove a suitable target (a drivable car) from a motivated offender (the alcohol-impaired driver). It also acts as a “guardian” to prevent the crime of operating a vehicle while under the influence.

Some researchers also refer to learning theory to explain the presence or absence of changed behavior after the device is removed from the vehicle (see Rauch et al. 2011). The theory suggests that offenders have to “unlearn” the drinking behavior and then must be repeatedly “rewarded” by successful driving episodes (that is, not being caught while driving intoxicated). If the device is installed for too short of a period, the offenders do not have a sufficient period to unlearn their previous behaviors. If the device is installed for a longer time, the driver is conditioned to learn about the negative effect (that drinking is “punished” by the inability to start the car).

Evaluation Outcomes

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Study 1
Subsequent Alcohol Traffic Violations

Beck and colleagues (1999) found that, within 12 months after assignment, 2.4 percent of the interlock program group and 6.7 percent of the control group had committed an alcohol traffic violation. This difference was statistically significant, with a relative risk of 0.36, meaning that being in the interlock program reduced a driver’s risk of committing a violation within the first year by approximately 64 percent.

During the second year, 3.5 percent of the remaining offenders in the interlock group and 2.6 percent of the remaining offenders in the control group had committed an alcohol traffic violation; however, this difference was not statistically significant. Over the combined 2 years of the study, 5.9 percent of the interlock group and 9.1 percent of the control group had committed at least one alcohol traffic violation. This difference was statistically significant, with a relative risk of 0.64.

Multivariate statistical tests and Kaplan–Meier survival curves provided similar results. The first-year effects were strong enough that there was a positive effect over the 2-year period, but there was no evidence that the first-year benefits extended into the second year.

Study 2
Alcohol-Related Violations

Rauch and colleagues (2011) found that the risk of a subsequent alcohol-related traffic violation significantly increased for those in the control group, those who were younger, and those who had more alcohol-related prior incidents. Also, being African American raised the risk of a subsequent violation during the postprogram period. After controlling for covariates, the study found that the interlock program was associated with reductions in the risk for new alcohol-related traffic violations by 36 percent during the 2-year program period, by 26 percent during the 2-year postprogram period, and by 32 percent during the overall 4-year period. These reductions are all statistically significant. In their survival analysis, they found that the experimental group had a higher probability of remaining free of new traffic violations than the control group.

Researchers noted that part of the program’s success likely stemmed from its status as an administrative program, which allowed for faster sanctions than a judicially managed program would. If true, then even greater success rates might be possible, since they found instances of “egregious violations” that remained unsanctioned and these violators were issued a letter at the end of 2 years congratulating them on their successful completion of the program. The researchers also noted that all offenders were eligible for relicensure because they had completed prelicensure sanctions, which could include treatment.

Posttreatment Effects
Most studies and a meta-analysis by the Cochrane Collaboration (Willis, Lybrand, and Bellamy 2004) indicate that interlock devices are effective in reducing recidivism when installed, but that the effect disappears when the device is removed. Rauch and colleagues, however, found that the effects of the treatment lasted beyond the installation of the device. After controlling for covariates, the study found that the interlock program was associated with reductions in the risk for new alcohol-related traffic violations by 26 percent during the 2-year postprogram period.
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Evaluation Methodology

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Study 1
Beck and colleagues (1999) used a randomized controlled trial to examine the effects of ignition interlock license restrictions in preventing recidivism in a group of Maryland drivers who had multiple alcohol-related driving offenses. Study participants were limited to multiple alcohol offenders and defined as drivers who had committed two or more alcohol traffic violations in the previous 5 years or three or more such violations in the previous 10 years. Participants had their licenses revoked or suspended but had been approved for relicensing by Maryland’s Medical Advisory Board. Offenders who were recommended for relicensing were randomly assigned to the interlock program (n=698) or to the control program (n=689).

The study sample was predominately male (90 percent) and white (84 percent), with an average age of 33. There were no significant differences between the groups on basic demographic characteristics. There were also no significant differences in the average number of previous alcohol violations (3.57 for the interlock program group and 3.61 for the control group).

Study participants assigned to the interlock program were notified by letter that they were approved for license reinstatement only if they agreed to a restriction prohibiting them from operating a vehicle without an interlock device for 12 months. This restriction was noted on their licenses. Interlock program participants had 45 days to get the device installed. They were also informed about treatment or support programs (e.g., Alcoholics Anonymous) that they were required to participate in. Failure to comply with any of these conditions of the program resulted in a suspension of driving privileges. Study participants assigned to the control program were notified by letter that they must comply with the restriction ordinarily placed on multiple alcohol offenders, including a driver’s license restriction stating that they may not drive after drinking any amount of alcohol. Most often, these restrictions included mandatory participation in Maryland’s Drinking Driving Monitoring Program, which required drivers to report regularly to a court-approved probation monitor who determined if the person was complying with the required treatment programs and whether the person was drinking or taking drugs. Failure to comply with the conditions resulted in suspension of driving privileges.

Each case was tracked by the Maryland Motor Vehicle Administration, which closely monitored compliance. The primary outcome measure of interest was whether the offender committed an alcohol traffic violation during the first year after entering the study (defined as 365 days after notification), the period during which the interlock license restriction was in effect and the device was required to be in the vehicle. Alcohol traffic violations were also examined during the second year (defined as beginning 366 days after notification and ending 365 days later), the period during which the license restriction had been lifted and the device would be removed. The data was analyzed from a relative risk perspective.

Study 2
Rauch and colleagues (2011) conducted a randomized controlled trial to test the effectiveness of Maryland’s use of ignition interlock to reduce alcohol-related violations. Drivers included in the study had two or more alcohol-related traffic violations in their lifetime. A total of 1,927 offenders applied for reinstatement of a Maryland driver’s license during 2000 and 2001. The Medical Advisory Board in Maryland randomly assigned 944 offenders to the ignition interlock group and 983 to the control group.

The two groups did not differ on any of the demographic or offense dimensions. The study sample was predominately male (88 percent) and white (80 percent), with an average age of 40. Offenders in both groups had an average of 3.3 alcohol-related priors.

Members of the control group were required to participate in the Drinking Driver Monitor Program. As part of this program, individuals routinely reported to a probation monitor who supervised participant compliance with the program and overall sobriety, administered breathalyzer tests, and ensured participant attendance at self-help or treatment meetings. All offenders, no matter their assignment, were prohibited from operating a motor vehicle with any alcohol in their system. The program lasted 2 years, and the researchers followed participants for an additional 2 years after drivers left the program.

The outcome of interest was alcohol-related violations, which included a preconviction administrative sanction, a conviction, probation before judgment, or a combination thereof. Data was provided by the Motor Vehicle Administration.

To accommodate the time lag between a violation and its final disposition and appearance on a record, researchers began data analysis 6 years after the last driver was enrolled in his or her respective program. Researchers used an intent-to-treat approach for analysis. Cox’s proportional hazard models were used to control for independent variables (driver age, sex, race, prior alcohol-related violations, and violation disposition category) that might influence the probability of reoffending. Additionally, statistical adjustments were made to take into account differences in program duration between the control group (21 months) and the experimental group (23 months).
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There is specific cost information for the Ignition Interlock Program in Maryland available at the Motor Vehicle Administration Web site (a link is provided under Additional References).
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Evidence-Base (Studies Reviewed)

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These sources were used in the development of the program profile:

Study 1
Beck, Kenneth H., William J. Rauch, Elizabeth A. Baker, and Allan F. Williams. 1999. “Effects of Ignition Interlock License Restrictions on Drivers With Multiple Alcohol Offenses: A Randomized Trial in Maryland.” American Journal of Public Health 89:1696–1700.

Study 2
Rauch, William J., Eileen M. Ahlin, Paul L. Zador, Jan M. Howard, and G. Doug Duncan. 2011. “Effects of Administrative Ignition Interlock License Restrictions on Drivers With Multiple Alcohol Offenses.” Journal of Experimental Criminology 7(2):127–48.
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Additional References

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These sources were used in the development of the program profile:

Elder, Randy W., Robert B. Voas, Doug Beirness, Ruth A. Shults, David A. Sleet, James L. Nichols, Richard Compton, and Task Force on Community Preventive Services. 2011. “Effectiveness of Ignition Interlocks for Preventing Alcohol-Impaired Driving and Alcohol-Related Crashes: A Community Guide Systematic Review.” American Journal of Preventive Medicine 40(3):362–76.

Magnusson, Patrick, Lisa Jakobsson, Sven Hultman. 2011. “Alcohol Interlock Systems in Sweden: 10 Years of Systematic Work.” American Journal of Preventive Medicine 40(3):378–79.

Motor Vehicle Administration. N.d. “Ignition Interlock Program.” Glen Burnie, Md.: Maryland Department of Transportation, Motor Vehicle Administration. Accessed Feb. 7, 2012.

Willis, Charlene, Sean Lybrand, and Nicholas Bellamy. 2004. “Alcohol Ignition Interlock Programs for Reducing Drink Driving Recidivism.” Cochrane Database of Systematic Reviews 3.

Zador, Paul L., Eileen M. Ahlin, William J. Rauch, Jan M. Howard, and G. Doug Duncan. 2011. “The Effects of Closer Monitoring on Driver Compliance With Interlock Restrictions.” Accident Analysis and Prevention 43(6):1960–67.
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Program Snapshot

Age: 19 - 75

Gender: Both

Race/Ethnicity: Black, American Indians/Alaska Native, Asian/Pacific Islander, Hispanic, White, Other

Geography: Rural, Suburban, Urban

Setting (Delivery): Other Community Setting

Program Type: Alcohol and Drug Therapy/Treatment, Situational Crime Prevention, Specific deterrence

Targeted Population: Alcohol and Other Drug (AOD) Offenders

Current Program Status: Active