Addiction A-Z

Ignition interlocks

An ignition interlock is an aftermarket piece of technology that is installed in a vehicle to prevent the driver from operating the vehicle if they have been drinking. Before starting the vehicle, the driver must breathe into the ignition interlock device. If the driver’s blood alcohol content (BAC) is over a pre-set limit, the ignition interlock will prevent the vehicle from starting. The device has an internal memory and records numerous activities including alcohol levels of the individual each time tested, date and time of each engine start/stop, alcohol results of engine retests while the engine is operating, and any attempts to tamper with or circumvent the system.

The ignition interlock was invented in the early 1970’s. By the mid-1980’s, they were introduced into the driving under the influence (DUI) and driving while intoxicated (DWI) offender marketplace. As of 2009, 47 states and the District of Columbia currently allow the use of alcohol ignition interlock devices for at least some DWI offenders. The three exceptions are Alabama, South Dakota and Vermont, which do not allow them. Some states mandate the use of ignition interlocks, while in others, judges, state administrators or even the offenders themselves, choose to apply this sanction or not.

An ignition interlock program is a structured means of providing a convicted impaired driver with restricted driving privileges. In order to participate in the program, individuals must meet eligibility criteria and agree to abide to enforceable program guidelines which may vary by state.

Seven states require ignition interlocks for all offenders, and 22 require it for repeat offenders. Still, of the approximately 1.4 million DWI arrests made each year, only about 146,000 ignition interlock devices are currently in use with impaired driving offenders.

Ignition interlock systems are becoming more and more sophisticated, thwarting attempts by drivers to get around them. Currently-available ignition interlock devices have anti-circumvention features that prevent tactics like having someone else blow into the device, or using compressed air or a balloon to blow into the ignition interlock. Many of the ways offenders have tried to go around the system in the past have been blocked by using pressure and temperature sensors, using running retests (random retests while the vehicle is operating), recording all events related to vehicle use, and others.

Why Ignition Interlocks Are Used

The argument for using ignition interlock device technology is fairly straightforward. Research shows that up to 75% of offenders drive illegally after a DWI arrest and license suspension. Among intoxicated drivers involved in fatal crashes, 14% have licenses that are currently suspended or revoked. In California, two-thirds of repeat offenders said they would very likely drive without a license. When individuals are intoxicated, they are unable to make appropriate driving judgments, putting others and themselves at risk when they get behind the wheel.

Ignition interlock programs provide a legal means for convicted offenders to drive while also enhancing public safety.

  • 877-825-8131