How it works: Connected to a car's electrical system, it won't let the engine start if the driver's blood-alcohol concentration tests 0.02 or higher. Drivers blow into a mouthpiece and must retake the test when the device beeps at random intervals during the drive. Newer devices will include cameras to ensure the driver is the one taking the test. Test failures are saved and reported at the end of the month.
Cost: About $50 to install, $100 per month to operate and $50 to remove. There are four vendors in the state, but once that number increases, costs will likely drop, officials said.
New rules: A law taking effect in July increases license revocation periods for several categories of DWI offenses. In most cases, offenders must have ignition interlock devices installed if they want to drive while their driving privileges are suspended.
