who is looking at your formspring now

Ignition Interlock Devices

An ignition interlock device is an electronic lockout device which is wired into the vehicle’s electrical system to prevent the vehicle from starting if the driver’s blood alcohol content is at or above .02 in Massachusetts. The device consists of a processing unit and a handset. The processing unit is mounted under the dashboard and the head is mounted in the passenger compartment, within the driver’s reach. The driver blows into the head to provide a breath sample which the processing unit analyzes for blood alcohol content. If the BAC is above .02, the vehicle will not start.

The head unit is the actual hand held user interface for the breathalyzer. The head contains the breath test portion of the device and a part of the log file. The head device instructs the user when to blow into the device to provide a required breath sample.

The processor or “relay unit” is the lower part of the system usually hidden under the dash of the vehicle out of view of the user. This part of the unit contains the other part of the log file. The relay and head record to memory the settings and the log files in case of power loss due to vehicle malfunction or tampering. The relay unit also incorporates a separate regulated power supply for the head. The Relay and head are connected with a specially designed cable using molded connectors. This allows the head to be easily removed during extremely cold weather.

To ensure that an intoxicated driver did not have another person blow into the device, the IID requires the driver to provide “rolling re-tests” at random intervals to confirm that the driver’s BAC is below the .02 threshold. Alcohol readings at or above .02 will result in “rolling-rest violations,” which can trigger 10 year license revocations.

To start the vehicle's engine, the driver must first blow and pass a deep lung breath sample into the Interlock. The IID will measure the alcohol concentration of the breath sample and prevent the vehicle from starting if the alcohol concentration exceeds a preset level of .02 in Massachusetts. Also, , the device records all breath test results, driving times, disconnection, and tampering.

Failing to provide rolling-rests upon request will also result in violations and potential license suspensions. These retests are randomly required whenever the engine is running which means that you will be required to take rolling tests even when the vehicle is not actually in motion.

Everything that you do with an ignition interlock device is electronically recorded. This means that every time you start and stop the vehicle, a record is being generated. Likewise, the IID tracks all initial start tests, rolling re-tests, high voltage, low voltage, circumvention, disconnection, aborted tests, passed tests, and failed tests. You must have this information downloaded on a monthly basis by a local ignition interlock service provider or the Registry will revoke your driver’s license.

The Massachusetts Registry of Motor Vehicles has many years of experience in administering the Ignition Interlock Program and it does a very good job of discerning and reconstructing what actually happened in a particular case based on interpreting the data provided by the device. Registry hearings regularly result in the imposition of 10 year, and possibly lifetime, license revocations due to ignition interlock violations. 

To be used in Massachusetts the IID must meet or exceed specifications required by the National Highway Traffic Safety Administration (NHSTA). Federal Register, Vol. 57, No. 67, “Model Specifications for Breath Alcohol Ignition Interlock Devices" published as of April 7, 1992. (Docket No. 97-07, notice 2).