New law requires ignition locks to prevent drunken driving

A new law takes effect July 1 that requires repeat alcohol-related offenders to install ignition interlock devices in their vehicles to keep them from driving intoxicated. The law was passed by the legislature and signed by Governor Matt Blunt in July, 2008.

An ignition interlock is a breath-testing instrument connected to a vehicle's ignition, horn and headlights. To start the vehicle, a driver must breathe into the device without registering a detectable blood alcohol concentration. The law will be administratively enforced by the Missouri Department of Revenue.

"The General Assembly sent a strong message when it passed Senate Bill 930/947," Karen Mitchell, director of the department, said. "The message was that those who repeatedly violate our state's drinking and driving laws must face the consequences of their actions. The department is now notifying affected people so that they will realize how the new law applies to them."

Richard Roth, Ph.D., of the community action and advocacy organization Impact D.W.I., said that more states are enacting laws to require ignition interlocks and that studies show they are helping to lower rates of driving while intoxicated.

"When you reach a break point, as we have in New Mexico, then you get a general deterrent effect," Roth said. "You get a significant reduction from the people who have an interlock themselves and you also get a deterrent effect on those who hear about them, they don't drive after drinking."

Roth has studied the situation for several years and has done three surveys to see what effect ignition interlocks are having.

"I do a survey about every 6 months to a year, closer to a year, and I have done three so far," Roth said. "The first showed about 100,000 devices in use around the country, the second about 130,000 and the last survey showed about 150,000 in use. New Mexico has more interlocks in use than anywhere else and since the law went into effect recidivism is down 30 percent."

While Roth is a strong proponent of interlock devices he recognizes that they have their limitations. Even with the limitations, Roth considers the interlocks the best way to handle offenders.

"The main way they get around them is by driving another car that doesn't have the device on them," Roth said. "Very few are having other people blow into the device. About three quarters are driving a different vehicle, about a quarter are driving a car with the license tags of the car requiring an interlock and only 0.6 percent have another person blow into the interlock. While they can be defeated, they are better than anything else."

One of the strengths of the devices is that even offenders themselves consider them a fair consequence.

"About 85 percent of the offenders consider it a fair sanction -- that's a good thing to say about it," Roth said. "The devices reduce re-arrests by a factor of three to four."

A Web site maintained by Impact D.W.I. calls the interlocks "Trigger locks on 2,000 pound weapons."

" Ignition Interlocks reduce DWI recidivism by up to 95 percent when installed," a statement on the site says. "New Mexico Law installs them on Vehicles because nothing else is as effective at reducing DWI recidivism."

Roth considers the ignition interlocks a good solution because it allows people to still have mobility while preventing undesirable behavior.

"Interlocks provide daily behavior-modification training to DWI Offenders and teach alcohol-free driving," Roth said.