New research on the benefits of ignition interlock devices

By Mary Ebeling

New research from the University of Pennsylvania finds that states that have passed laws requiring ignition-interlock devices (IIDs) for all drivers convicted of drunk driving have seen a collective 15 percent drop in deaths from drunk-driving crashes compared with rates in states without this requirement. While the report findings provide useful information on the use of this tool for protecting people from drunk drivers, other studies show that IIDs alone are not sufficient to curb drunk driving. To be most effective, states should adopt IID laws that kick in on the first offense and provide sufficient oversight to monitor continued use of the IIDs. Governments implementing IID laws can also learn from recent studies showing that without sufficient oversight, installation and use of IIDs can be spotty.

While every state has some form of an IID law, currently, just 25 states require IIDs for all DUI offenders, including first-time offenders. According to Mothers Against Drunk Driving, on average a driver drives drunk 80 times prior to their first arrest and three out of four drunk drivers with suspended licenses continue to drive. These numbers provide a compelling argument for IID installation.

Monitoring compliance with IID installation orders is a key element to the success of these programs. Rates of compliance vary widely between locations. New York State conducted a study showing that in New York City between 2010 and 2015 only 5 percent, or 111, of the court ordered 2,166 IIDs were installed.  Research in Washington State and Wisconsin show that just over half of drunk driving offenders actually installed the court-ordered IIDs in their cars. It is also becoming increasingly clear that effective oversight would require that the IID order be tied to the convicted individual rather than the vehicle, thus decreasing the likelihood of simply driving another car. Without effective mechanisms in place to track the use of these devices the efficacy of using IIDs to curb drunk driving significantly decreases.

The University of Pennsylvania article found that “at least 25 percent of drunk drivers are recidivists, and recidivists are over represented in fatal crashes.” These findings suggest a strong safety benefit in universal application of IIDs, beginning with the first offense. However, for the IID programs to work well, states should adopt effective processes and procedures for tracking IID use. Effective monitoring programs can help improve the use of IIDs and counter the criticism that the IID programs are ineffective.

Mary Ebeling is a Transportation Policy Analyst at SSTI.