Ignition Interlock Basics

An ignition interlock is a mechanism, similar to a breathalyzer, that is installed into the driver’s dashboard. Before the vehicle can be started, the driver must breathe into the device, which measures blood alcohol content (BAC). If the driver’s BAC is over a certain measurement, typically .02% or .04%, the car will not start, stopping another drunken driver from entering the roadway.

After starting the engine, the ignition interlock device will randomly require another breath sample. The purpose of this measure is to stop sober people from blowing into the device, starting the car, and then allowing the drunk driver to get behind the wheel. If the sample isn’t provided or it exceeds the BAC limit, the device logs the events and then sets off an alarm until the ignition is turned off.

Most ignition interlocks work by using an ethanol-specific fuel cell as a sensor. Although not as accurate as infrared spectroscopy, fuel cells are more cost efficient and analysis specific for alcohol. The mechanism costs the offender about $75 a month because of necessary calibration. In addition, the device keeps a recorded log of activity, which typically must be downloaded and printed out at 30, 60, or 90 day intervals.

If you have been accused of drunken driving and need legal representation, contact the Rhode Island drunk driving lawyer Matthew Marin at 401-287-4384.