Harris said the devices require a driver to take a breathalyzer test before the vehicle will start. The device will also require the driver to take “rolling tests” — exhaling into the system while the car is running. If a driver’s blood-alcohol content rises above a certain level — typically .02 or .05 percent — the vehicle shuts off.

Missouri took a step in that direction with a new law that goes into effect Wednesday.

The law targets primarily repeat DWI offenders who are seeking to regain their licenses and it could require as many as 70,000 Missouri residents convicted of alcohol-related traffic offenses to install breath-monitoring devices on their vehicles if they want to legally drive after July 1. It also applies to anyone convicted of involuntary manslaughter while driving drunk.

In the past few years, about 20 states have passed laws mandating their use for first-time or repeat offenders, according to MADD.

Missouri’s law could have a particularly broad affect because it applies to people convicted of drunken driving as long as 10 years ago who are just now eligible to regain their licenses.

The Missouri Department of Revenue, which issues driver’s licenses, plans to send more than 70,000 letters to offenders in early July notifying them of the need to get ignition interlocks to legally drive again. The law requires them to be used for six months.

Clogged court

Jasper County Prosecutor Dean Dankelson said alcohol-related driving offenses represent a large portion of the court’s docket.

“There are probably not as many as we have of the drug-related cases, but I would say it would be a high percentage of what we do,” he said.

Dankelson said Missouri laws create a graduated punishment system for dealing with DWIs. A first offense is considered a class B misdemeanor, while each subsequent offense results in a more severe penalty. Four or more offenses and a person is considered a “chronic offender” — a class B felony.

A corresponding offense is excessive blood-alcohol content. Dankelson said the standard for such a charge is simply operating a motor vehicle with a BAC over the legal limit of .08, whereas a DWI offense must also meet certain criteria — speeding, swerving or erratic driving.

There were 164 DWI felony cases filed against multiple offenders in Jasper County in 2008 — those with two or more previous convictions — according to information from the Missouri Judiciary Criminal System. There were 337 misdemeanor cases filed against first-time offenders.

McDonald County reported 183 cases filed against first-time offenders in 2008 and 90 felony cases filed against repeat offenders. Newton County reported 187 first-time offenses and 70 cases filed against repeat offenders.

BAC vs. DWI

Judge Joseph Schoeberl is head of Jasper County’s Fourth Judicial Circuit in Carthage. His court is primarily responsible for the initial setting of alcohol-related driving offenses.