Alcohol-impaired driving is a stubborn problem. The rate of fatalities in crashes involving drivers with a blood-alcohol concentration of .08 or more has fallen by half since 1982. But there is still a huge amount of carnage.
In the United States, some 10,000 people die in such accidents each year. It's the equivalent of a 9/11 attack every four months.
In recent decades, efforts to curb drunk driving have grown -- raising the legal drinking age from 18 to 21, stepping up police enforcement, lowering permissible blood-alcohol levels and stiffening penalties.
Social norms have also evolved. Groups like Mothers Against Drunk Driving, founded by a woman whose daughter was killed by a chronic offender, have fostered greater awareness and intolerance of a practice that used to be joked about.
But changes like these can prevent only so many episodes of driving under the influence. Some people just refuse to reform, and as long as they have free access to four wheels, they remain a menace.
So 15 states use another remedy. They force everyone convicted of DUI to install an ignition interlock before they can regain driving privileges. More than 20 other states mandate these devices only for the most serious offenders.
Congress may also get into the act. Legislation in the House of Representatives would give extra highway funds to states that mandate interlocks for all DUIs.
With an interlock, you have to pass a breath test before your car will start. Inducing chronic drunks to sober up is hard. But disabling their vehicles is not. It's also supremely cost-effective, at least for the rest of us -- because the expense of installing and maintaining the device is borne by the guilty party.
States that have gone this route typically achieve big improvements. A 2011 report from the federal Centers for Disease Control and Prevention found that "after these devices were installed, re-arrest rates for alcohol-impaired driving decreased by a median of 67 percent relative to drivers with suspended licenses."
There are, alas, ways for incorrigible boozers to defeat the device. They can get a friend or family member to blow for them, or they can drive a different car. It's not a perfect check.