More lives are saved when all drunk driving offenders—not just some—are required to use ignition interlocks, new research from Johns Hopkins suggests.
State laws mandating vehicle lockdown devices for all DUI offenders are associated a 7 percent decrease in fatal drunk driving crashes, the study concluded. That translates to an estimated 1,250 deadly collisions prevented since states first started passing those mandatory laws back in 1993, according to researchers from both the Johns Hopkins Bloomberg School of Public Health and the Colorado School of Public Health.
Today, all 50 U.S. states have some type of law regarding ignition interlocks—devices that prevent a car from starting if they detect a certain level of alcohol on the driver's breath. The new research, published this week in The American Journal of Preventive Medicine, is the first of its kind to look at the effectiveness of different types of these state laws.
As of last March, 26 states had mandatory laws to require all individuals convicted of a DUI offense to use an interlock in order to drive legally. Researchers found that these types of laws seem to be much more effective than those that apply to only certain categories of offenders (for example, repeat offenders or those with a very high blood alcohol content).
"Interlock laws which are mandatory for all DUI offenders save lives," says study leader Emma Beth McGinty, deputy director at the Johns Hopkins Center for Mental Health and Addiction Policy Research.
The researchers used federal data to study the effects of interlock laws on trends in alcohol-involved fatal crashes between 1982 and 2013.
"Until recently, there hasn't been any evidence on whether these laws prevent alcohol-involved fatal crashes, and specifically whether mandatory laws are more effective than permissive and partial laws," McGinty says. "Our study suggests that they are effective, and it's encouraging to see more and more states moving towards this evidence-based policy change."
Since 2005, more than 20 states have adopted interlock laws for all drunk-driving offenses, McGinty notes, adding: "We'd like to see the remaining states follow suit."Read more from School of Public Health