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Back to Archives | Back to July 2010 Contents 

Ignition Interlocks

By Brian A. Ursino, Director of Law Enforcement, American Association of Motor Vehicle Administrators

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espite ongoing efforts by law enforcement; governmental agencies; the judiciary; Mothers Against Drunk Driving (MADD); and many other traffic safety partners, 11,773 people were killed in alcohol-impaired driving crashes in 2008. This accounts for 32 percent of the 37,261 traffic fatalities that occurred in 2008—more than three in every ten traffic deaths. Moreover, the National Highway Traffic Safety Administration (NHTSA) indicates that distracted driving is the proximate cause in approximately 16 percent of traffic fatalities, 1 meaning that alcohol-impaired driving is the root cause of twice as many traffic fatalities as distracted driving.

In addition to the fatalities, nearly 500,000 people are injured every year in alcohol-impaired traffic crashes. It is important to remember the faces behind these numbers—not only those who themselves have lost their lives or have been injured, but the bereaved family members and friends who exponentially multiply the number of victims of these unacceptably high traffic injury and fatality numbers.

The author is not suggesting that every available resource be focused on the alcohol-impaired driving problem when empirical evidence shows that other behaviors, including distracted driving and speed, also contribute to significant percentages of our nation’s traffic fatalities. However, the author does suggest that federal, state, and local governments and their partners in traffic safety should avoid becoming disproportionately focused on any one issue. A better return on the investment of scarce traffic safety resources is realized by keeping a proportional investment focus. Applying appropriate resources to alcohol-impaired driving strategies that will eventually eliminate alcohol-impaired driving will more quickly achieve the goals outlined in “Toward Zero Deaths: A National Strategy on Highway Safety,” an effort to develop a national approach to eliminating highway fatalities as a threat to public and personal health.2

Why Ignition Interlocks

In the highway safety community, there has been a long-standing theory that first-time alcohol offenders are just multiple offenders that had not previously been caught. But these ideas were based on anecdotal evidence and were absent any real empirical evidence to validate this theory. Without that empirical evidence, year after year, some legislators, judges, lawyers, and policy makers have gone to great lengths to protect first-time offenders. They argue that first-time offenders are largely drivers who were one sip over the limit. However, according to a study published in May 2010 by the American Journal of Public Health,3 the recidivism rate among first offenders more closely resembles that of second offenders than of non-offenders. Men and women are at equal risk of recidivating once they have had a first violation documented. Any alcohol-impaired driving violation, not limited to a conviction, is a marker for future recidivism.

The study’s strength resides in its examination of more than 100 million driving records for a time period from 1973 to 2008. The study shows that first offense leniency is no longer appropriate because the behavior of the first offender and the second offender is virtually the same. Given enough time, and if allowed to reoffend due to the leniency often shown first offenders, those first offenders are likely to become repeat offenders.

In addition, the Centers for Disease Control (CDC) has reviewed ignition interlocks and has stated that “based on strong evidence of the effectiveness of interlocks in reducing re-arrest rates, the [CDC] Task Force recommended that ignition interlock programs be implemented.”4

The simple reason that alcohol-impaired drivers continue to drink and drive is because they can. Approximately 75 percent of people with a suspended driver’s license continue to drive.5 Although not the only solution, ignition interlocks represent a proven technology intervention that significantly reduces recidivism on the part of the alcohol-impaired driver. Research shows that ignition interlocks reduce recidivism among offenders with reductions in subsequent arrests ranging from 50 percent to 90 percent.6

Ignition Interlocks: Where Are We?

As of May 2010, 12 states require ignition interlocks for all offenders; 9 states require ignition interlocks for high blood-alcohol concentration (BAC) and repeat offenders; 8 states have other ignition interlock requirements; and 18 states have made the interlocks optional. Just 3 states have no ignition interlock law at all (see figure 1).7

Currently, 81 million Americans live in states that have all-offender ignition interlock laws, compared to 2 million Americans in 2006, and are therefore afforded additional protection against the alcohol-impaired driver. However, arrest data show ignition interlocks are still a vastly underutilized tool. This underutilization is evident by simply comparing the approximately 180,000 interlocks in use in the United States in 2008 to the approximately 1.4 million impaired driving arrests made. This comparison shows there still is a long way to go to using ignition interlocks to their full potential.

Ignition interlock technology is moving along two parallel paths. One path is the movement toward requiring all alcohol-impaired offenders to use currently available ignition interlock technology. The second path is to develop and implement an advanced passive ignition interlock technology that can be manufactured as standard equipment in every car. The concept for this technology is for the vehicle to be able to determine if the driver is at or above the illegal BAC limit of .08 grams per deciliter (g/dL) in an even less intrusive way than buckling a seat belt, with the vehicle not operating if such a BAC level is detected.

The Short-Term Solution: Wider Use of Current Technology

As seen in figure 1, in the United States, 12 of the 50 states currently require ignition interlocks for all offenders. Although California does not have a statewide all-offender interlock law, the California Assembly did pass legislation authorizing an all-offender ignition interlock pilot program in four counties that account for 14 million people who reside in the state.

The evidence-based research recently published in the American Journal of Public Health should promote the passage of all-offender ignition interlocks in more states. Although states in general do not support federal mandates that drive state-level policy, especially when backed-up with sanctions (on traffic safety issues these sanctions are usually in the form of withholding a portion of the federal aid highway funding they are eligible to receive), that is an entirely separate debate. What is evident is how effective such federal sanctions can be. Two cases in point are the national uniformity in the implementation of effective laws such as the 21-year-old minimum legal drinking age and .08 per se BAC laws—now in all 50 states.

The most current draft of the Federal Highway Reauthorization Bill currently awaiting congressional approval contains hard sanction language to incentivize those states without all-offender ignition interlock laws to pass such laws to receive all the federal aid highway dollars their states will be eligible for under the next six-year highway reauthorization funding cycle.

In the 12 states that have taken the initiative to pass and implement all-offender ignition interlock laws, differences exist in the administrative construct of these laws. Acknowledging the lack of available research to support the most effective all-offender ignition interlock laws has caused the American Association of Motor Vehicle Administrators (AAMVA) to encourage NHTSA to examine best practices and draft guidelines for a model program to assist states in implementing such programs. This will contribute to the establishment of the most consistent and effective state programs across the United States. Even those states that have already enacted all-offender ignition interlock laws can amend their existing laws if best practices emerge that could strengthen the all-offender ignition interlock laws already in place. In fact, in 2010 the Washington State Legislature strengthened the state’s all-offender ignition interlock law originally passed in 2008.

As recommended by AAMVA, the outcomes of developing a model ignition interlock program could be the following:

  • Model state legislation for an all-offender ignition interlock policy

  • Best practices and guidelines for an ignition interlock program

  • Standards for data logger downloads and reporting

  • Standards for progressive sanctioning of interlock data logger violations

  • Standards for time limitations and removal criteria for interlocks

  • Measurement criteria to determine the program’s effectiveness

The Future Technology of Passive Ignition Interlocks

While current ignition interlocks represent a technology intervention that can reduce recidivism on the part of the alcohol-impaired driver, it is recognized that preventing recidivism is not as good as preventing even the first offense from occurring. Research on future technology, known as the Driver Alcohol Detection System for Safety (DADSS), has already begun. DADSS is the result of a cooperative research agreement currently under way between the Automotive Coalition for Traffic Safety (ACTS) and the NHTSA. The agreement is a public-private partnership with both entities providing $1 million per year for five years. DADSS is not an ignition interlock device one would find on a convicted alcohol-impaired driver’s car today; rather, the purpose of this $10 million agreement is to research, develop, and demonstrate non-invasive, in-vehicle alcohol detection technologies that can quickly and accurately measure a driver’s BAC. If the device detects the driver is at or above the illegal BAC limit of .08 g/dL, the car could not be driven. However, if the technology is successful, the experience for a driver below the BAC limit would be no different than in a car without the device.

Three companies are currently under contract to develop prototype technologies to meet program goals that also include a tamper-resistant device that can be readily integrated into the vehicle’s existing systems with little to no maintenance.

The Insurance Institute of Highway Safety (IIHS) recently conducted a poll that found 64 percent of Americans believe that reliable, advanced alcohol-detection technology that would prevent an alcohol-impaired driver from operating a vehicle is a good idea.

But this $10 million is only seed money. Additional funding will be required to bring this technology to market, and legislation is being introduced in the U.S. Congress to provide this funding.

A reasonable question to ask is why bother passing all-offender ignition interlock laws if future technology will all but entirely solve the problem? First, this new technology has not been successfully developed, and, second, this technology will not come to market for another decade and will take at least a decade beyond that for the technology to saturate the market. Overall, the wait will be 20 more years before this technology is available in most, but not all, vehicles registered in the United States. For now, passage of all-offender ignition interlock laws using the current technology will help move the needle toward zero deaths on the nation’s roadways. ■


1NHTSA data (presentation, 2010 Lifesavers Conference, Philadelphia, Pa., April 11–13, 2010); and “2008 Traffic Safety Annual Assessment–Highlights,” Traffic Safety Facts: Crash Stats, June 2009, DOT HS 811 172, 5, (accessed May 21, 2010).
2For more information, please visit
3William J. Rauch et al., “Risk of Alcohol-Impaired Driving Recidivism Among First Offenders and Multiple Offenders,” American Journal of Public Health 100 (May 2010): 919–924.
4Centers for Disease Control and Prevention, “Injury Prevention & Control: Motor Vehicle Safety: Impaired Driving,” (accessed May 18, 2010).
5R.C. Peck et al., “Driver License Strategies for Controlling the Persistent DUI Offender: Strategies for Dealing with the Persistent Drinking Driver,” Transportation Research Board, Transportation Research Circular 437 (Washington, D.C.: National Research Council, 1995), 48–49.
6Robert B. Voas et al., “The Alberta Interlock Program: The Evaluation of a Province-Wide Program on DUI Recidivism,” Addiction 94, no. 12 (December 1999): 1849–1859.
7Data provided by Mothers against Drunk Driving, Office of Public Policy.

Please cite as:

Brian A. Ursino, "Ignition Interlocks," The Police Chief 77 (July 2010): 24–27, (insert access date).



From The Police Chief, vol. LXXVII, no. 7, July 2010. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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