Repeat offenders are a significant portion of the drunk driving problem – about one-third of all DUI arrests each year are of people who have been convicted previously of driving under the influence. (Fell, 1995) Considering that between 50 and 75 percent of those whose licenses are suspended or revoked as the result of driving under the influence continue to drive without their license, (Nichols and Ross, 1990) (Voas and Tippetts, 1994) revoking a license is good, but not always enough.
Alcohol ignition interlocks are proven to be an effective tool in the battle against drunk driving. Ignition interlocks prevent people who have alcohol in their system from driving a car. An operator breathes into an interlock device to determine blood alcohol concentration. If there is measurable alcohol in the blood, the vehicle does not start.
As one might expect, this stops offenders from re-offending while the interlock device is on the vehicle. Studies have shown ignition interlocks are an average of 64 percent effective in reducing repeat drunk driving offenses. (Lybrand, 2004) Interlocks have been shown to be effective in Maryland (Beck, 1999), Alberta (Voas, et al, 1999), California (Tashima and Helander, 1999), and elsewhere (Weinrath, 1997) (Coben, 1999) with results ranging from 50 to 90 percent reductions in subsequent offenses by those offenders who were assigned interlock devices, compared with those who were not.