Locked out! Today's ignition interlock systems, along with better monitoring and stricter penalties, are making our roads safer.

• Author: Teigen, Anne
• Position: TRAFFIC SAFETY

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Drunken drivers continue to be a major safety threat on America's roadways. Despite myriad efforts by state, federal and local governments, along with improvements in vehicle technology, about 10,000 people die every year on the nation's roads and highways because people who have been drinking choose to drive.

Although the proportion of traffic fatalities caused by intoxicated drivers has decreased from more than half of all crashes in 1986 to just a third in 2014, 1 in 8 people surveyed by AAA in 2014 admitted to driving even when they thought their blood alcohol content (BAC) was over the legal limit. Indeed, approximately 1 million impaired drivers are convicted annually in the United States.

Recognizing the dangers of impaired driving, state legislators have continued not only to refine state laws and programs, but also to embrace technology that can help limit repeat offenses by convicted drunken drivers.

One now-widespread technological option is the ignition interlock. Interlock devices connect to a car's starter system and do not allow the car to start if a preset level of alcohol--typically well below the illegal level of .08--is detected in the driver's breath. Along with public awareness campaigns, the devices have been effective in preventing drunken driving by repeat offenders. Use of ignition interlocks can reduce the rate of re-arrests for driving under the influence by up to 70 percent, according to a 2014 Government Accountability Office report. "Taking a license away from offenders does not keep them from driving in general, and it certainly does not stop them from driving drunk.

Installing a device that won't let them start their car, on the other hand, does both..." says Alabama Representative Allen Farley (R).

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New and Improved

Today's ignition interlocks are not the same as the ones used 30 years ago, however. The old systems often mistook cigarette smoke, perfume and breath-fresheners for alcohol, resulting in many false positives. They also showed a wide variation of readings and had a short life span.

Research and development have improved the reliability of the devices, which now use fuel cell units calibrated to be more accurate and consistent. The devices are smaller, more affordable and less susceptible to tampering. All new devices require periodic retesting while the car is running to ensure that the driver is not drinking once the car is started, and many are also...