1. Maryland Ignition Interlock Program

Maryland Ignition Interlock Program

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).

Intervention ID

19 to 75


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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