Motor Vehicle Ignition Interlocks: In-vehicle Devices that Monitor Alcohol Levels of Motor Vehicle Operators

Report No: 90-R11

Published in 1990

About the report:

This project was initiated at the request of the Department of Motor Vehicles as a response to House Joint Resolution 378 (1989). The resolution requested an evaluation of research studies on ignition interlocks and a determination of possible benefits to the Commonwealth of Virginia from using this technology to control drunken driving. A survey of other states found that since the first law was enacted in California in 1986, another 15 states have passed some form of legislation dealing with the installation of ignition interlock devices. These laws primarily target recidivists, persons younger than 21, and offenders with a very high BAC. Sanctions are applied at the discretion of the court as a supplemental condition of probation or license restriction. These state statutes also deal with BAC threshold levels, tampering with the devices, insurance, and liability limits. A number of legal and economic issues that must be considered if Virginia initiates an ignition interlock program are discussed in the report. These issues include the authority of the state, equal access for indigents, tort liability, operational costs, administrative costs, and costs to defendants. Product information from manufacturers and the results of laboratory studies indicate that the devices currently on the market would fulfill the needs of an interlock program. The operational characteristics, reliability, and accuracy of these devices are sufficient for use by defendants convicted of drunken driving. Although a number of states have passed legislation and have established ignition interlock programs, very little is known about the actual operations of these programs because they have not been in existence very long. Some preliminary data suggests that the programs might have had a positive impact on safety, but no definitive result is currently available because a thorough evaluation has yet to be completed for even one program. It is recommended that Virginia delay legislative action.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.


Other Authors

Cole B. Wilson, Charles B. Stoke

Last updated: December 27, 2023

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