Ignition Interlocks are devices about the size of a cell phone installed in a vehicle's dashboard.  These devices are designed to keep people who have been convicted of driving under the influence (DUI) from starting their vehicle after they have consumed alcohol.  It works like a Breathalyzer -- a convicted drunk driver must blow into the device in order to start their vehicle.  If they have a measurable amount of alcohol in their system, the vehicle will not start.

These devices are a simple and economic way to ensure convicted drunk driving offenders can drive to and from work, but cannot drive under the influence of alcohol.


Do ignition interlock devices keep people from having repeat DUI offenses?

The Center for Disease Control (CDC) found repeat drunk driving offenses were reduced by about two-thirds due to interlock devices.

The International Council on Alcohol, Drugs and Traffic Safety's (ICADTS) found ignition interlock devices, as well as monitoring, led to a 40-95% reduction in the conviction rate of people who were previously arrested for DUI. This is important, because the rate of DUI convictions is a good predicator of crash risk involvement.


As of August 2015, 25 states require interlocks for all offenders.

Kentucky's Ignition Interlock Law -- In March 2015, the Kentucky Legislature passed Senate Bill 133 requiring ignition interlock devices for all repeat DUI offenders.  The final version of the bill does not require first-time DUI offenders to have the devices installed unless there's an aggravating circumstance, such as excessive speed or driving drunk with a child in the car. 


How do ignition interlocks prevent tampering? 

  1. Temperature and Air Gauges -- The devices have temperature and air gauges to ensures a person and not a machine is providing the air sample.
  2. Learned Skill -- Blowing into an interlock is a learned skill that requires specific training that would most likely be difficult for an impaired person to administer.
  3. Running Retests -- Running retests require offenders to blow into the device at random intervals once the vehicle has been allowed to start.  It reminds the driver about scheduled checks.  If a check is missed, the device will not allow the car to start.
  4. Alerts Law Enforcement to Failed/ Bypassed Retests -- If a driver drives bypasses or fails a running retest, the horn will honk and the lights will flash to alert law enforcement.  The devices are wired to a vehicle's ignition system not the engine, and for safety reasons will not stop a vehicle while it is in motion.
  5. Car Battery Tampering -- If the driver tampers with the battery, the device will also know if the car’s power has been interrupted.
  6. Tamper-Proof Seals -- There are also tamper-proof seals on interlocks.

The majority of the public supports requiring ignition interlocks for all convicted drunk driving offenders based on the following studies cited from www.madd.org:


Click here for answers to other frequently asked questions about Ignition Interlocks from MADD.org.