Alcohol-related traffic deaths have gone down in states that require everyone convicted of driving under the influence to install a device that blocks drunk driving.
Such deaths were 15 percent less common in states that required ignition interlocks, which make drivers pass a Breathalyzer-like test before the engine will start, than in other states, according to a University of Pennsylvania study published Thursday in the American Journal of Public Health.
The study estimated that universal ignition interlock requirements saved 915 lives in 18 states between 2007 and 2013. Four additional states enacted such laws in 2014 and 2015.
Pennsylvania and New Jersey use the devices for repeat offenders, but not after all first offenses. A bill that would expand use of interlocks passed the Senate unanimously in Pennsylvania last year and is scheduled for discussion Monday by a House committee. Convicted drunk drivers would not be able to regain their licenses without first using the machines for a year, if the bill becomes law.
In New Jersey, Gov. Christie conditionally vetoed universal interlock legislation last year because that bill did away with a mandatory license suspension.
All states have some kind of ignition interlock law. Some use the machines at a judge's discretion or only when blood alcohol levels are particularly high. New Jersey, for example, uses them in first offenders found to have nearly twice the legal definition of drunken driving or more.
Frank Harris, director of state government affairs for Mothers Against Drunk Driving, said MADD strongly supports quick access to interlocks because drunk drivers often continue to drive on suspended licenses. The devices, he said, are more effective than suspensions at keeping drunks off the road.
"The sooner someone's on interlock, the better," he said.
Harris said that 6,000 Pennsylvanians are currently using ignition interlocks. The devices detected 78,000 attempts to drive drunk between October 2003 and Dec. 1, 2015.
A further benefit of interlocks, said Elinore Kaufman, who led the Penn study, is that the devices make it easier for people to get to work. Difficulty finding alternative transportation is one reason driving on a suspended license is so tempting.
"It targets the thing we're really concerned about," she said. "It's not a punishment. It's a preventative device."
She said there will never be enough police to fully enforce license suspensions.
"To me, this is a commonsense policy that's in place in a whole lot of states," she said of interlock laws. "It's really low-hanging fruit for other states."
Harris said it costs from $75 to $150 to install an interlock and $1,000 a year in monitoring fees. Drivers are responsible for the costs. Some states, Kaufman said, have programs that help low-income drivers.
Alcohol is involved in 30 percent of fatal wrecks, a proportion that has held steady for years. In general, fatal accidents have been declining due to better roads and cars.
Kaufman, a student in Penn's health policy master's program who is also a general surgery resident at New York-Presbyterian Weill Cornell Medical College, found drinking-related deaths declined more in states with universal interlock laws. It took three years after a law's implementation for the full impact to become apparent.
The adjusted rate of alcohol-related crash deaths in the new study was 4.7 per 100,000 in population in universal interlock states compared with 5.5 per 100,000 in the other states.
These are not drunken-driving deaths. Legally, the drunken driving definition is a blood alcohol concentration (BAC) of 0.08 percent. Most interlock devices, however, are set at 0.02 percent. (New Jersey uses 0.05.)
Because of the lower interlock limits, Kaufman decided to look at all fatal crashes in which at least one driver had a BAC above zero. She said the trends were similar in crashes involving higher alcohol levels, but did not publish that analysis and declined to release specific numbers.
Impairment begins long before drinkers hit the legal limit, Kaufman said. "Your risk of crashing goes up as soon as there's any alcohol at all in your body," she said.
The study also did not track specific individuals convicted of DUIs. It was asking a more global question, Kaufman said. "Does this law make us as a community safer or not?"
BY THE NUMBERS
Lives saved by ignition interlocks in 18 states between 2007 and 2013.
Pennsylvanians currently using ignition interlocks.
Number of attempts to drive drunk between October 2003 and Dec. 1, 2015 that were detected by Pennsylvania devices.
SOURCE: University of Pennsylvania study, Mothers Against Drunk Driving