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New Tennessee Law Requires Ignition Interlock for DUI Offenders

Happy New Year, Tennessee! Well maybe for those caught driving drunk in that state. Under new legislation that became effective on January 1, 2011, if you're convicted of driving under the influence, even for the first time, in Tennessee, you could be required by law to use an ignition interlock on your vehicle.

Ignition Interlock

An ignition interlock requires a driver to blow into a tube before starting the vehicle. If the device detects alcohol, the vehicle's lights flash, the horn sounds, and the vehicle won't start. Yes, it's embarrassing. "I would definitely say there are some social ramifications to it," noted one Tennessee state trooper. He believes the new law will become more of a deterrent because it is not only embarrassing, but it's inconvenient as well. The interlock device requires periodic tests and the device sounds an alarm when it's time for one.

New Requirements

Until last year, an interlock was not required unless an operator had one or often two prior DUI convictions. Now, if a driver registers a blood-alcohol content of .15 or higher, it's interlock time. The limit in Tennessee is .08; therefore, the .15 requirement is not intended to punish those who may be unaware that their blood-alcohol levels are over the limit. The new law also requires interlock use for drunk drivers who have a person younger than age 18 in the car, and in some cases for drivers who refuse Breathalyzer tests. A similar law was passed in four California counties in July 2010.


There are presently about 600 vehicles in Tennessee that have required ignition interlock devices. In addition to embarrassment and inconvenience, add expensive to the reasons you do not want an interlock. In Wisconsin, for example, interlock devices can cost offenders $900 per year. One offender had to sell his son's car because Wisconsin's law requires every vehicle titled to an offender to be interlock equipped.

In Wisconsin, where the law has been in effect since July, the interlock seems to be having a big effect on younger drivers, in particular. According to a supplier of the device, "The first offenders have a rude awakening. They are embarrassed. . . . They know they made a mistake and are easy to work with."