Effectiveness of Adopted Laws and Programs
Effectiveness Directly Tied to Statutes’ Clarity and Specificity, Enforcement and Monitoring Efforts
A 2014 NHTSA report estimates that only 15%-20% of arrested DUI offenders actually install IIDs. Estimated installation rates for those ordered to install the devices vary in individual states and range from 20% in California to 56% in Washington. Localities where judges required strict penalties—such as jail time or house arrest—for those violating installation requirements had higher installation rates at 62% and 71%.
While IID are powerful tools to fight alcohol-impaired driving, traffic safety researchers point out that sometimes well-meaning laws can be a major obstacle in increasing their use and effectiveness. In some states, vendors are required to send reports to authorities when installing or removing the device, but not when there is a violation.
According to NHTSA, there are currently no widely accepted reporting standards, and manufacturers have their own standards. Experts urge states to concretely and specifically mandate the information that must be included in monthly monitoring reports and how this information will be used.
According to NHTSA, there are currently no widely accepted reporting standards, and manufacturers have their own standards. Experts urge states to concretely and specifically mandate the information that must be included in monthly monitoring reports and how this information will be used, as well as define key terms used in such reports, such as “circumvention,” “failed retest,” etc.
Experts also agree that ideal IID laws should require a certain period of time without violations before removal is possible. Consistent, periodic reports and their correct interpretation are vital to enforce such compliance-based removals. Effective laws clearly define what constitutes a violation and require all violations to be reported. Prohibited acts should include alcohol-related events and circumvention and tampering attempts.
Close monitoring is equally essential for the success of IID programs. Washington, for example, has a Compliance Based Review (CBR) period of 180 days. To be eligible for removal, offenders may not fail a test within that 180-day timeframe—defined as attempting to start their vehicle with a BAC of .04 or more, .025 for a retest—fail to take a random retest, attempt to circumvent or fail to appear when required for maintenance, repair, calibrate, monitoring, inspection or replacement of the device.
Washington developed a program for monitoring offenders with failed tests or who attempted to circumvent the devices. Two officers conduct home visits to educate participants about the state’s IID program and the six-month CBR period and inform them that they have been identified as having failed tests or circumvention attempts. According to an AAMVA report, the visits remind participants that they are being monitored, and “of the hundred that are visited each year, it is rare that the same individual is visited more than once.”
A randomized trial in Maryland showed that close monitoring, including reviewing reporting data received, and sending letters to offenders informing them of violations and their consequences reduced failed tests and tampering attempts.
Additionally, many states lack a central electronic repository for IID information, which can lead to information getting lost or not being available to the right person at the right time.
Reduction in Impaired-Driving
Studies have shown that IIDs reduce recidivism—by up to 70%—among first-time, repeat and high-risk offenders while they are installed. However, once the IIDs are removed, the offender’s recidivism rates increase, in particular for repeat and high-risk offenders. Yet, when coupling IIDs with alcohol use disorder treatment, CDC researchers found decreased recidivism. The policy studied was a Florida law mandating alcohol treatment for DUI offenders using interlock. Offenders who accumulated three interlock violations—defined as two occasions within four hours in which the device prevented the driver from starting the vehicle—were required to participate in alcohol use disorder treatment. Recidivism among such offenders was reduced by 32% after the device was removed, compared to the control group that did not receive treatment.
Additionally, compliance-based monitoring and removal practices discussed above, which have been adopted by more and more states in recent years, also help prevent recidivism rates. While further research is needed to determine the optimal amount of time, compliance-based removal is a recommended best practice.
Most traffic safety experts advocate for all-offender IID requirements. An article studying the effects of ignition interlock laws on fatal crashes between 1982-2013 found that mandatory laws for all offenders “would have significant public health benefit” and “are more effective at reducing alcohol-involved fatal crashes than laws requiring interlocks for segments of high-risk offenders.” The researchers found that all-offender IID laws prevented a total of 1,250 alcohol-impaired fatal crashes during the time frame studied. A more recent study concluded that states with universal interlock laws saw on average a 15% decrease in alcohol-involved crash deaths when compared with states that have less stringent interlock requirements.
Persistent Concerns and Limitations
One inherent limitation of IID is that they only detect alcohol, which leaves the possibility for offenders to switch to other substances. Unlike for alcohol, screening for drug impairment is difficult. There is not only a wide array of impairing drugs, but drugs can stay in a person’s system for prolonged periods of time, and there is no correlation of any other drug beyond alcohol to determine impairment. However, while IID would not be able to prevent a driver impaired only by drugs from starting their vehicle, they do prevent offenders who have consumed a combination of drugs and alcohol from driving. Polysubstance-impaired driving—driving after consuming a combination of drugs or drugs and alcohol—has been on the rise in recent years and in particular during the Covid-19 public health emergency. NHTSA’s latest data shows that the prevalence of multiple drugs or drugs and alcohol in seriously or fatally injured drivers (excluding motorcyclists) went from 16.9% during the fourth quarter of 2019 to 24.9% during the third quarter of 2020.
Other concerns include negative side effects of rolling tests, accessibility and elevated costs.
A recent news article explains that IID requirements, and especially randomized rolling retests—additional breath samples the driver has to provide while driving during varying intervals to prevent the engine from going off—have been associated with crashes. Such tests help assure the driver does not consume alcohol after starting their vehicle. However, rolling tests can be highly distracting, require the driver to manipulate the device with their hands and can make them take their eyes off the road. According to the article, during a 10-year time frame, interlocks were involved in 58 crashes in North Carolina.
Accessibility and elevated costs for offenders continue to be of concern. It is difficult for some offenders to install IID in their vehicles, in particular in many rural jurisdictions that don’t have any vendors. Requiring interlock service providers to serve rural areas as a prerequisite for obtaining a contract with the state is a suggested potential solution. Additionally, while many states have adopted indigent programs, high installation and maintenance costs are still major factors preventing higher installation rates. Costs can increase significantly for rural offenders if they have to drive long distances to install and maintain the IID. These additional costs are not covered by indigent programs.