Reducing Alcohol-impaired Driving: Publicized Sobriety Checkpoint Programs

Task Force Finding and Rationale Statement

Definition

Publicized sobriety checkpoint programs are a form of high visibility enforcement where law enforcement officers systematically stop drivers to assess their degree of alcohol impairment. Media efforts to publicize the enforcement activity are an integral part of these programs. The program goal is to reduce alcohol-impaired driving by increasing the public's perceived risk of arrest while also arresting alcohol-impaired drivers identified at checkpoints.

There are two types of sobriety checkpoints:

• Random Breath Testing (RBT) - all stopped drivers are given breath tests for blood alcohol concentration (BAC) levels. RBT is used in Australia and several European countries.
• Selective Breath Testing (SBT) - police must have reason to suspect that a stopped driver is intoxicated before a breath test can be requested. SBT is used in the United States.

Task Force Finding

The Community Preventive Services Task Force recommends publicized sobriety checkpoint programs based on strong evidence of effectiveness in reducing alcohol-impaired driving.

Rationale

Basis of Finding

The Task Force finding is based on earlier evidence from a Community Guide systematic review published in 2001 (Shults et al., 23 studies, search period January 1980 - June 2000) along with more recent evidence (15 studies, search period July 2000 - March 2012) reviewed in 2012. Based on this updated review, the Task Force recommendation for the effectiveness of this intervention remains positive and unchanged. Evidence presented below comes from the updated search period.

Primary evidence for this Task Force recommendation comes from 10 studies (reported in five papers) that evaluated the impact of publicized sobriety checkpoint programs on alcohol-involved fatal crashes in the United States. These 10 studies showed a median relative percentage decrease in alcohol-involved fatal crashes of 8.9% (interquartile interval [IQI]: -16.5% to 3.5%). The remaining five studies evaluated changes in outcomes that could not be combined with alcohol-involved fatal crashes. Two of these studies that were from the United Studies found decreases of 64% and 28% in the percentage of drivers with a BAC above the legal limit, and one study found a 4.6% decrease in the rate of alcohol-involved fatalities per vehicle mile traveled. Another U.S. study found a decrease of 18.8% in alcohol-involved collisions. A study from New Zealand found a decrease of 22% in serious and fatal nighttime crashes (a well-established proxy for alcohol-involved driving crashes). These results are consistent in direction with those from the 2001 Community Guide review.

Applicability and Generalizability Issues

Of the included studies from the updated search period, 14 were conducted in the U.S., and one was conducted in New Zealand. Most studies focused on the general population, and two studies—one that focused on college-aged drivers and one that reported results separately for men aged 21 to 34 years—found reductions in alcohol-involved driving outcomes, showing publicized sobriety checkpoint programs are also effective among young adults, a particularly high-risk population.

Two studies that evaluated the use of "low-manpower" staffed checkpoints—those using 11 law enforcement personnel or fewer—found decreases in the percent of nighttime drivers with a BAC ≥0.08% and in the percent of alcohol-involved fatal crashes. These findings suggest that publicized "low-manpower" staffed checkpoint programs are effective.

Evidence from the updated search period showed a smaller median effect for sobriety checkpoint interventions in the U.S. when compared with evidence from the 2001 original Community Guide review; this is most likely due to changes in the environment around alcohol-impaired driving. Since the original review was published in 2001, alcohol-impaired driving and crashes in the U.S. have declined. Laws have been passed to reduce alcohol-impaired driving, and the public has become more familiar with sobriety checkpoints. Finally, improvements in engineering have led to safer cars and fewer crash deaths (NHTSA, 2012). Because there is less opportunity to achieve large declines in rates of alcohol-involved motor vehicle crashes, the smaller median effect from the updated search period is noteworthy.

Data Quality Issues

Of the 15 studies included from the updated search period, 10 were interrupted time series with a comparison group, one was a controlled before-after study, two were interrupted times series studies, and two were before-after studies.

Other Benefits and Harms

Additional benefits of sobriety checkpoints were identified in this review. Checkpoints may help law enforcement officers detect violations of the law that would otherwise be missed. For example, officers at a checkpoint can easily determine whether occupants are not using mandated safety restraints. Additionally, a visible law enforcement presence may reduce crime in an area.

Additional benefits of sobriety checkpoints were identified in this review. Checkpoints may help law enforcement officers detect violations of the law that would otherwise be missed. For example, officers at a checkpoint can easily determine whether occupants are not using mandated safety restraints. Additionally, a visible law enforcement presence may reduce crime in an area.

Implementation Issues

Considerations for implementation include legal restrictions against using checkpoints in 12 states. Additionally, an integral part of publicized sobriety checkpoint programs is the use of media, either paid ads or news stories (i.e. "earned" media); to publicize the program and increase the population's perceived risk of arrest for alcohol-impaired driving. Six studies in the review reported that following implementation of a publicized checkpoint intervention, there were increases ranging from 4% to 32% in the percent of people from a targeted community who had seen or heard messages about drinking and driving or checkpoints showing that the intervention did increase awareness.

Securing the necessary law enforcement staff to implement sobriety checkpoints presents another challenge to implementation. Law enforcement agencies are often understaffed and their attention and resources are divided, with competition from the Department of Homeland Security and other priority areas. In addition, sobriety checkpoints are typically conducted during times when alcohol-impaired drivers are most likely to be on the roads, such as weekend evenings, and staff overtime is often required.

Compared with regular and saturation patrols, sobriety checkpoints are harder and potentially more dangerous to implement during adverse weather conditions as checkpoints require law enforcement personnel to stand outside while patrols allow them to spend most of their time in vehicles. Law enforcement also may be less supportive of sobriety checkpoints because they can result in fewer arrests of impaired drivers compared to other forms of high visibility enforcement, such as saturation patrols.

A final implementation challenge is conducting the sobriety checkpoint in a manner that maximizes the effectiveness. The National Highway Traffic Safety Administration publishes a how-to guide for planning and publicizing sobriety checkpoints which describes how to implement checkpoints effectively (NHTSA, 2002). This guide recommends selecting a site for conducting checkpoints by identifying locations that have a high incidence of impaired driving-related crashes or fatalities and are safe for both law enforcement and motor vehicle occupants. Vehicles are randomly selected (e.g., every fifth vehicle) for driver assessment and standardized methods are used for determining who and how to test for alcohol. These precautions can help avoid implementation concerns about racial profiling by ensuring that sites, vehicles, and drivers are selected based on standardized procedures, and that the methods used to detect impaired drivers are not left up to an individual officer's discretion.

Economic Efficiency

The economic review identified five cost-benefit studies of interventions completed before 2000. All five studies found the benefits of publicized sobriety checkpoint programs were greater than the costs. Four studies from the original review reported net benefits ranging from $3.7 million to $224 million (in 1997 U.S. dollars), and benefit-to-cost ratios ranging from 2:1 to 57:1. One study from the updated search period reported net benefits of $445.76 million (in 2011 U.S. dollars), and a benefit-to-cost ratio of 14:1. The variation in the range of economic outcomes can be explained by modeling assumptions about various costs and health outcomes and the time period of their accrual; for example, the Arthurson study evaluated the long-term program benefit for fatal crashes avoided and, as a result, had a higher benefit-to-cost ratio compared to other studies. Overall, the evidence indicated that, for publicized sobriety checkpoint programs, the economic benefits exceeded the intervention costs.

Other Economic Findings

One cost-effectiveness study reported a cost of $5,787 per alcohol-involved motor vehicle crash averted. Two other cost-effectiveness studies found costs of $549 to $628 per percentage point reduction in nighttime drinking drivers with BAC ≥0.08%, and a cost of $492 per percentage point reduction in self-reported driving after drinking. When results from these three studies (one "low-manpower" staffed and two "regular-manpower" staffed) are compared, low-manpower staffed sobriety checkpoint programs are found to cost less than regular-manpower staffed programs.

Nine studies reported costs of media advertising and publicity ranging from $1 to $82 per 100 persons. Five of these nine studies evaluated the cost-effectiveness of media advertising and publicity and found it ranged from $29 to $257 per additional 100 persons who became aware of the sobriety checkpoint program. The incremental cost of media varied based on the length, density, and duration of publicity, and the type of media used.

Evidence and Research Gaps

The original Community Guide review, published in 2001, discussed several research gaps, most of which were not addressed by the evidence found during the updated search period. Only one study evaluated random breath testing checkpoints, making it impossible to adequately compare RBT and SBT. Similarly, there was not enough evidence from the updated search period to assess the effects of passive alcohol sensors that allow law enforcement officers to detect any measured presence of alcohol in a vehicle.

There also was insufficient information available in the studies from the updated search period to determine whether paid versus earned media had different effects on study outcomes because most studies either used both types or did not report which type was used. Further research should include descriptions and measures of media used.

The 2001 review also asked whether posting warning signs about checkpoints would have an impact on their deterrent effects. There was no evidence available from the updated search period to evaluate this question, and it now needs to be expanded as motorists can download applications to their smartphones to alert them to the presence and location of nearby checkpoints (Bertolucci, 2011). As the use of smartphones becomes more widespread, it will be important to understand the impact these applications may have on the effectiveness of sobriety checkpoints.

Finally, most of the studies provided either no or partial information about the costs of conducting sobriety checkpoints. Reporting complete costs for implementation, staffing, and media efforts, including the cost of paid media and dollar equivalent of earned media is necessary for a complete review of economic effectiveness. Also, further research is needed to clarify the long-term economic benefits for publicized sobriety checkpoint programs.

References

AAA Foundation for Traffic Safety. 2009 Traffic Safety Culture Index. Washington, D.C.: Author. Available at URL http://www.aaafoundation.org/pdf/2009TSCIndexFinalReport.pdf [PDF] Accessed May 1, 2012

Bertolucci J. Avoid DUI checkpoints? No App for That, Senators Say. PC World. Mar 22, 2011. Available at: http://www.pcworld.com/article/222884/avoid_dui_checkpoints_no_app_for_that_senators_say.html. Accessed April 6, 2012

National Highway Traffic Safety Administration. An Analysis of Recent Improvements to Vehicle Safety. Washington, DC: U.S. Department of Transportation, National Highway Traffic Safety Administration, 2012. DOT HS 811 572. Available at URL http://www-nrd.nhtsa.dot.gov/Pubs/811572.pdf. [PDF]. Accessed August 29, 2012

National Highway Traffic Safety Administration (NHTSA). Saturation Patrols & Sobriety Checkpoints Guide. A How-to Guide for Planning and Publicizing Impaired Driving Enforcement Efforts. Washington, DC: U.S. Department of Transportation, National Highway Traffic Safety Administration, 2002. DOT HS 809 063. Available at URL: http://www.nhtsa.gov/people/injury/alcohol/saturation_patrols/index.html. Accessed August 29, 2012

Shults RA, Elder RW, Sleet DA, et al. Reviews of evidence regarding interventions to reduce alcohol-impaired driving. [PDF - 2.29 MB] Am J Prev Med 2001;21(4S):66–88.

Task Force on Community Preventive Services. Recommendations to reduce injuries to motor vehicle occupants: increasing child safety seat use, increasing safety belt use, and reducing alcohol-impaired driving. [PDF - 2.30MB] Am J Prev Med 2001;21(4S):16–22.

U.S. Supreme Court. 1990. Michigan Dept. of State Police v. Sitz, 496 U.S. 444 (1990) 496 U.S. 444. Michigan Dept. of State Police et al. v. Sitz et al. Certiorari to the Court of Appeals of Michigan. No. 88-1897. Argued February 27, 1990. Decided June 14, 1990. Available at URL: http://caselaw.lp.findlaw.com/scripts/getcase.pl?navby=case&court=us&vol=496&page=444. Accessed May 1, 2012