According to the Governors Highway Safety Association (GHSA), 31% of all fatal crashes in 2021 were caused by alcohol-impaired drivers. In fact, repeat DUI offenders are more likely to be involved in DUI-related fatal crashes than first-time offenders. To help combat this problem, all 50 states have adopted ignition interlock device (IID) programs, which aim to prevent individuals that have consumed alcohol from driving.
However, enforcement of compliance with these programs varies between states, leading to different rates of repeat DUI offenses across the country.
How Does Ignition Interlock Work?
Car breathalyzer devices, also known as Breath Alcohol Ignition Interlock Devices (BAIIDs) are small handheld devices that measure the amount of alcohol in the breath (Breath Alcohol Content, or BrAC). These devices prevent the vehicle from starting until a breath alcohol test is taken and passed.
Interlock devices require the driver to submit a breath sample, usually through a small tube. If the breath sample is adequate, the device converts the breath sample into an electrical current. If the client did not blow hard enough, the device alerts the client, who must continue to submit breath samples until the device indicates that the sample is sufficient. Through chemical oxidation, the alcohol from the client’s breath is accumulated.
Because an ignition interlock device’s fuel cell is designed to be sensitive to ethanol—a type of alcohol found in beer, wine, and liquor—IIDs detect and measure the amount of alcohol in the breath sample and compare it to a pre-determined level. If the driver’s breath alcohol content is higher than the pre-programmed level, the interlock device may disable the vehicle’s ignition, flash the lights, and sound the horn.
In addition, the vehicle usually cannot be started until the client passes a breath test or the device is reset by an IID service provider. If the client’s breath alcohol content is lower than the pre-programmed level, the ignition will start normally. Some interlock devices contain a camera to verify that the correct client is submitting the breath test.
IIDs also log several kinds of data including the results of the breath sample; the amount of time operating the vehicle; any attempts to tamper with, disable, or circumvent the IID; and the dates that the device is serviced.
History of Ignition Interlock Devices and Legislation
According to CDC, the first alcohol ignition interlock was developed in 1969 but interlocks with alcohol-detection technology did not become standard until the 1980s. In 1986, California passed legislation allowing for initial testing of alcohol interlocks to prevent repeat drunk driving offenders, with other states following suit. Federal legislation began to financially incentivize states with ignition interlock legislation, and today, all states have alcohol interlock programs.
However, the enforcement of compliance with ignition interlock devices varies significantly in each state.
Discrepancies in DUI Recidivism Rates Based on State Laws
Many studies have indicated that ignition interlock devices are highly effective in reducing recidivism and in turn, saving lives. While all states currently have ignition interlock programs, only 33 states and the District of Columbia have compliance-based removal laws. These laws mandate that drivers with an IID installed in their vehicle must have a specific number of violation-free days before the device is removed.
Examining this more closely, the Governors Highway Safety Association (GHSA) conducted a study with alcohol-impaired driving recidivism data from January 1st, 2016, to December 31st, 2019. For the purposes of comparison, two states with compliance-based IID removal laws (Tennessee and Washington) and two states without these laws (Arkansas and Iowa) were analyzed. From 2016 – 2019, Tennessee saw recidivism rates of 1.7% and Washington at 3.7%. Comparatively, in the two states without IID compliance laws, the rates of recidivism were 5.6% in Arkansas, and 6% in Iowa.
Although there are many other factors that can impact repeat DUI offenses across the country, the GHSA study indicates that mandating compliance with ignition interlock devices may help lower repeat DUI offenses—which account for a significant portion of drunk driving-related crashes and deaths.
In fact, several studies have shown that DUI recidivism rates can range from 21% – 47%. As such, laws that force DUI offenders to complete their ignition interlock program with an extended period of sobriety can help significantly reduce repeat DUI offenses. This not only helps reduce drunk driving deaths but also supports clients in taking the first steps to achieve long-term sobriety.
A recent study even indicated that if systems like IIDs were installed on all vehicles, 9,000 to 12,000 deaths could be prevented every year.
Although ignition interlock devices are not the complete solution to drunk driving crashes and deaths, they can promote changes in behavior that save lives, especially when regulations are enforced to mandate compliance.