Research

Questions & Answers

1a)	Do alcohol interlocks reduce drunk-driving recidivism among offenders?
1b)	Do alcohol interlocks reduce recidivism among first time offenders?
1c)	Do alcohol interlocks reduce recidivism among hardcore offenders?
2a)	How often do judges impose sentences which require alcohol interlock?
2b)	What are some factors that contribute to judicial reluctance to impose alcohol interlocks as a sentence?
3a)	Do offenders comply with orders to install alcohol interlocks?
3b)	Once installed, do offenders comply with alcohol interlock devices?
4)	Can the information from the interlock data recording device be used to predict future offences?
5)	What do participants/offenders think about alcohol interlocks?
6)	How does the alcohol interlock impact the participant's family?
7)	What is the relationship between alcohol interlocks and treatment?
8)	What happens when the alcohol interlock is removed from the vehicle?
9)	How do the costs for ordering alcohol interlocks compare to the benefits?
10a)	What are the strengths of the existing research?
10b)	What are the limitations of the existing research?
11)	What research is still needed?

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1a) Do alcohol interlocks reduce drunk-driving recidivism among offenders?

• Research shows that alcohol interlocks reduce recidivism among both first offenders and repeat offenders, including hardcore offenders (also known as persistent/chronic drinkers and repeat offenders who repeatedly drive after drinking with extremely high blood alcohol concentrations and are resistant to change this behaviour). More than 10 evaluations of interlock applications have reported reductions in recidivism ranging from 35 – 90% (Voas and Marques 2003; Vezina 2002; Tippetts and Voas 1997; Coben and Larkin 1999) with an average reduction of 64% (Willis et al. 2005).

1b) Do alcohol interlocks reduce recidivism among first time offenders?

• Four studies, each with a unique population, different measures of recidivism, and varying evaluation periods, have concluded that alcohol interlocks are effective in reducing recidivism among first-time offenders (EMT Group 1990; Morse and Elliot 1992; Tippets and Voas 1998; Voas et al. 1999).
• An evaluation study conducted in New Mexico (2004) compared data from a court ordered interlock group (n=862) with data from a non-interlock group (n=11,973). The findings confirmed that the recidivism rate was significantly lower among first offenders on the interlock. The re-arrest rate per year for interlock participants was 3.51%, while the non-interlocked group had a significantly higher re-arrest rate of 7.09% (Voas et al. 2005).
• An Alberta, Canada study compared first offenders with alcohol interlocks to a control group of reinstated and non-interlocked drivers and found an 89% reduction in recidivism when comparing first offenders with alcohol interlocks to reinstated drivers (Voas et al. 1999). The study found a 95% reduction in recidivism when comparing first offenders with alcohol interlock to ineligible drivers. Ineligible subjects included those individuals who committed a DWI while their licence was suspended resulting in an extension of the suspension period.

1c) Do alcohol interlocks reduce recidivism among hardcore offenders?

• Five studies involving chronic or repeat DWI offenders found that alcohol interlocks were one of the most promising strategies to prevent a subsequent occurrence of DWI behaviour (EMT Group 1990; Popkin et al. 1992; Morse and Elliot 1992; Jones 1993; Weinrath 1997).
• An evaluation conducted in Maryland used offenders with multiple convictions who were eligible for licence reinstatement (Beck et al. 1999). The offenders (N=1,387) were randomly assigned to participate in an alcohol interlock program (experimental group: N=689), or in the post-licencing treatment program (control group: N=689). The alcohol traffic violation rate during the first year was significantly less for participants in the interlock program (2.4%) than for those in the control group (6.7%). Participation in the alcohol interlock program reduced offenders’ risk of committing an alcohol traffic violation within the first year by approximately 65%.
• A study conducted in Illinois examined the recidivism rates of two groups of drivers who had their drivers licences revoked for alcohol-impaired driving and who received restricted driving permits (Raub et al. 2003). Participants in both groups were chronic offenders and had to meet the rigorous criterion for inclusion in the study. The participants were divided into those who were required to install the alcohol interlock (N=1,408) and those who were not (N=1,384). It was found that 20 (1.3%) of the 1,560 drivers originally in the experimental group were rearrested compared to 94 (8.7%) of the 1,384 drivers in the control group who had been rearrested. In other words, offenders who used the alcohol interlock were one-fifth as likely to be arrested for a DWI during the first year compared to those who did not have the device. The authors also noted that once the alcohol interlock was removed, there was a rapid return to pre-device recidivism.

2a) How often do judges impose sentences which require alcohol interlock?

• The rate of imposition of alcohol interlocks has been historically low and inconsistent. A California study reported that following the passage of legislation requiring judges to order interlock ignition devices for all drivers convicted of driving on a DWI-suspended driver licence, an installation order was part of sentencing for less than one-quarter of repeat DWI offenders (DeYoung 2002).

2b) What are some factors that contribute to judicial reluctance to impose alcohol interlocks as a sentence?

• Historical and personal experiences in sentencing offenders may be based on inconsistent findings with respect to whether and to what extent the alcohol interlock is effective and can influence decision-making.
• The interlock device appears too harsh for first offenders and too lenient for repeat offenders (Vanlaar 2005).
• There is concern that the cost to offenders is prohibitive, contrary to existing research which reveals that the daily cost of this sanction is less than $3.00 per day (Robertson and Simpson 2003).
• There are concerns regarding the technological effectiveness of the device, complications surrounding its use, and the amount of effort required to monitor offender compliance.
• Lack of current and comprehensive information and educational materials has resulted in a pattern of decision-making based on out-dated information. This creates challenges for practitioners who lack time to gather and review relevant information (Beirness 2001).

3a) Do offenders comply with orders to install alcohol interlocks?

• Many studies conducted over the past two decades estimate that between 25-75% of suspended or revoked drivers continue to drive (Waller 1985; Hagen et al.1980; Sadler and Perrine 1984; Peck et al. 1985; Ross and Gonzales 1988; Griffin III and De La Zerda 2000).
• Recent research suggests that judges do not consistently impose alcohol interlock sentences and that offender non-compliance is common. A California study revealed that of 775 DWI offenders sentenced to install an alcohol interlock as a condition of probation, 191 offenders (approximately 25%) did not have the device installed (DeYoung 2002).
• Research also indicates that repeat offenders are less likely to install an alcohol interlock compared to first offenders (Voas and Tippetts 1997).
• Offenders fail to install alcohol interlocks for various reasons: to avoid compliance, inconvenience, embarrassment, and cost.

3b) Once installed, do offenders comply with alcohol interlock devices?

• During the first several weeks, offenders often try to circumvent the alcohol interlock by tampering with breath samples and attempting to electronically disengage the device.

• Research indicates that tampering and circumvention rates decrease over time, perhaps as the offender becomes more used to the device and gains an understanding of the sophisticated technology involved and the futility of trying to beat the device.
• Some offenders do bypass the alcohol interlock by driving a vehicle that is not equipped with one. However, strong reductions in recidivism found in research suggest this is infrequent.

4) Can the information from the interlock data recording device be used to predict future offences?

• Research suggests that a high rate of blood alcohol concentration (BAC) fail readings from the alcohol interlock data recording device, particularly in excess of .02%, is predictive of the likelihood of recidivism (Marques et al. 2003; Beirness and Marques 2004).
• The presence of elevated BAC tests during early morning hours can also assist in predicting future DWI offences. The presence of two or more elevated BAC test results during the early morning hours further bolsters the predictive model regarding the likelihood of future DWI offences (Beirness and Marques 2004).
• Several variables, but primarily more prior DWI’s, more interlock warnings and failures logged during the first five months of interlock usage predict more than 60% of repeat DWI violations, with a false positive rate of less than 10% (Marques et al. 2001).

5) What do participants/offenders think about alcohol interlocks?

• A study conducted in the United Kingdom found that many offenders credited the alcohol interlock for stopping or reducing impaired driving and/or reduced their drinking, invoked serious thought about their drinking habits, and assisted in changing their drinking patterns (Beirness et al. 2007).
• There are two types of concerns that are usually raised by offenders. First, offenders express some concerns regarding social aspects such as the embarrassment, stigma, and frustration of providing a breath sample, particularly when it is inconvenient for the offender to do so (Beirness 2001). Second, some offenders report technical challenges such as the perceived long warm-up time, invalid samples, and the frequency of re-tests (Beirness et al. 2007).

6) How does the alcohol interlock impact the participant's family?

• Family members were particularly favorable to the use of the alcohol interlock as a measure seen as providing reassurance that the offender is not driving while impaired (Beirness et al. 2007). Families were generally positive about the interlock experience and the impact it had on their loved ones.  Many reported a positive change in drinking behaviour and the peace of mind provided by having the alcohol interlock installed.

7) What is the relationship between alcohol interlocks and treatment?

• Alcohol interlocks serve as a nexus between criminal justice sanctions and substance abuse treatment, by effectively restricting an offenders’ driving privileges while giving the offender the opportunity to learn how alcohol consumption affects behaviour (Beirness 2001).
• While treatment for alcohol abuse can be a lengthy process with setbacks and relapses, the alcohol interlock provides a safety net to greatly reduce the likelihood that such relapses do not result in impaired driving (Beirness et al. 1998).
• Alcohol interlocks were never intended as a treatment for alcohol abuse, thus the installation and use of an alcohol interlock device alone cannot be expected to result in a long-term change in the amount and extent of alcohol consumption (Beirness 2001).
• Ultimately, the relationship between alcohol interlocks and treatment providers should be strengthened as part of an alcohol interlock program. More research examining the beneficial effect of the integration of rehabilitation and alcohol interlock programs is needed (Beirness et al. 2003).

8) What happens when the alcohol interlock is removed from the vehicle?

• Numerous studies demonstrate that alcohol interlocks have a beneficial impact on recidivism as long as the device is installed in the vehicle. Specifically, existing studies converge at the finding that once the device is removed, recidivism rates return to levels comparable to rates of those who did not have an interlock installed (Beirness 2001; Beirness et al. 1998; Jones 1993; Popkin et al. 1993; Coben and Larkin 1999; Marques et al. 2001; DeYoung 2002; Raub et al. 2003).
• As a consequence of increased recidivism following the removal of the alcohol interlock, several studies have reported that employing alcohol interlocks may be necessary as a long-term or permanent condition of driving for repeat offenders (DeYoung 2002; Rauch and Ahlin 2003; Raub et al. 2003; Beirness et al. 2003).

9) How do the costs for ordering alcohol interlocks compare to the benefits?

• The findings of an overview of cost-benefit analyses demonstrate that new motor vehicle safety features, including the alcohol interlock, are some of the most cost-effective measures and contribute to the largest reductions in the number of fatalities (European Road Safety Observatory 2006).
• The report cites a Norwegian study (Elvik 1999) which notes that installing alcohol interlocks in the vehicles of all impaired drivers would have an estimated benefit-cost ratio of 8.75. This means that for every dollar spent on alcohol interlocks, there will be a saving of nine dollars.

10a) What are the strengths of the existing research?

• The strengths of the existing research include: highly comparable findings from several studies and a convergence of evidence produced by the majority of these studies; sufficient overall sample sizes to allow for broad application of findings; and a wide range of offender status and populations examined as control groups.
• Alcohol interlock research covers a broad spectrum of studies conducted in worldwide jurisdictions in Scandinavia (Norway, Sweden), Europe (Belgium, the United Kingdom), the United States (California, Illinois, Maryland, New Mexico, Ohio, Oregon, West Virginia) and Canada (Alberta, Quebec).
• In addition to investigating alcohol interlocks in private vehicles, the available body of research also includes research on alcohol interlocks installed in commercial vehicles and public transportation.
• The current body of research includes evaluations of court-based and administrative programs, providing comparative material that may be useful for jurisdictions considering which approach to adopt.

10b) What are the limitations of the existing research?

• Control groups: Most of the difficulties surrounding control groups involve the inability and lack of resources to select a control group equivalent to the experimental – interlock – group (e.g., comparable groups of licence-suspended impaired drivers). In order to create an appropriate control group a population of previously convicted impaired drivers would be randomly assigned to two groups: one receiving the alcohol interlock and the other one not receiving it (Raub et al. 2003). This can be challenging in offender studies for ethical and legal reasons.
• Selection bias: Studies involving voluntary participants may have a selection bias effect, which means that there are some differences in these participants compared to other eligible offenders which can affect the result. DWI offenders assigned to an interlock program are often those who present the highest risk of reconviction which may result in findings much different than the conclusions drawn from a group of volunteers.
• A particular type of selection bias which needs to be accounted for is the impact of judicial discretion (Coben and Larkin 1999). Experimental design or randomized studies are difficult to execute because judges, for important reasons, hesitate to impose this sanction on a random basis. The sanction severely restricts the activities of half of the offenders in this manner, while not imposing the same or similar restrictions on the other half on the basis of nothing more than the luck of when their case was sentenced. While this limitation is a difficult obstacle to overcome, the differences in experimental and control groups could be addressed in future studies by assigning 100 consecutive subjects to a control group (Fulkerson 2003).

11) What research is still needed?

• Optimal structure for alcohol interlock programs: such programs may be effective if they operate under either an administrative agency (e.g., motor vehicle administration) or the judicial system.

• Monitoring function for alcohol interlock programs: research must be conducted to determine who should be responsible for monitoring offenders, their compliance, and the performance of the device. This may involve a probation officer based on a judicial program or service providers based on an administrative program.
• Process evaluations of alcohol interlock programs: future research is needed to investigate the details of how an alcohol interlock program currently operates compared to how the program should operate. Evaluations also must be conducted on compliance with sentencing legislation requiring judges to order alcohol interlocks and compliance with court orders for installations by offenders.
• Outcome evaluations of alcohol interlock programs: all prior studies of alcohol interlocks are limited in that they relied upon re-arrest rate, an incomplete measure of DWI recidivism, as the sole and primary outcome measure (Coben and Larkin 1999). Future studies should routinely and more carefully examine crash rates, alcohol-related crash rates, death, and injuries as additional outcomes.
• Interaction between alcohol interlocks and treatment: research is needed to demonstrate the beneficial effect of the integration of rehabilitation and interlock programs. Evidence suggests that the alcohol interlock effectively incapacitates drivers from operating a motor vehicle while impaired, but the device is not intended to assume a treatment role which would include modifying an offender’s behaviour. Further research could help solidify and strengthen the relationship with treatment providers (Beirness et al. 2003).