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In-Car Breathalyzers: A Primer

Only four states mandate the installation of in-car "interlock" breathalyzers for first-time drunk driving convictions and Illinois is one of them (enacted on Jan. 1, 2009), along with New Mexico, Arizona and Louisiana.

The device serves as a lock between the driver and the car's ignition, requiring the breath of a sober driver as its key. The car won't start if the device registers a blood alcohol level above .05 percent. It also requires periodic breath samples throughout the trip to ensure that someone else hasn't blown into the device to start the car.

It still leaves open the opportunity for a sober passenger to blow into the breathalyzer when prompted. Another concern is the possibility of false-positives as a result of using mouthwash (most of it contains alcohol) or eating sugary baked goods, which can be overcome by waiting about 15 or so minutes before blowing into the device.

Illinois' Breath Alcohol Ignition Interlock Device (BAIID) program is considered the toughest of the four, since the Secretary of State's office monitors the results of the tests each time convicted DUI offenders attempt to start their cars.

It costs about $100 to install the device, plus $80 per month in rental fees and a $30 monthly monitoring fee. For offenders who wish to participate in the program but can't afford the costs, the law establishes an indigency fund.

The law was championed by Mothers Against Drunk Driving, which helped craft the legislation (Senate Bill 300) in order to both prevent repeat offenses and allow those convicted of a DUI to still get to work.

Offenders are free to opt-out of the BAIID program but it does offer an alternative to suspension.