New York's ignition interlock law took effect in August 2010. A conviction for driving while intoxicated earns even a first-time offender an ignition interlock device in his vehicle. The device is mandatory regardless of the offender's blood alcohol level at the time of arrest -- 0.08 plus a conviction equals ignition interlock.

The state is one of just 15 that mandate interlock devices for offenders who tested at 0.08. Other states require the devices for hard-core and repeat offenders. Some states require devices similar to but less sophisticated than interlocks. But, if Mothers Against Drunk Driving and the U.S. Centers for Disease Control and Prevention are successful, every state will adopt a law as strict as New York's.

Interlock devices have proved more effective than other efforts to keep drunk drivers off the road. For example, MADD advocated in the past for license suspensions for repeat and chronic offenders, but 75 percent ignored the suspensions. States with interlock mandates, though, have shown as much as a 67 percent decline in DWI re-arrest rates.

An ignition interlock works like a Breathalyzer. The driver blows into the device, and the device measures the blood alcohol content. If the BAC exceeds the set limit -- often below the state's legal limit -- the car won't start. As technology has advanced, the devices have become harder to trick. The point for MADD and the CDC is that the law assures that an intoxicated driver doesn't get behind the wheel.

Neither the devices nor the mandates have met with universal approval, of course. Critics have a number of concerns, and we'll get into those in our next post.

Source: MSNBC, "Curbing drunken drivers: Should ignition interlock be required on every car?" Jim Gold, Jan. 5, 2012