Motor Vehicle Injury – Safety Belts: Primary (vs. Secondary) Enforcement Laws

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Snapshot

Summary of CPSTF Finding

The Community Preventive Services Task Force (CPSTF) recommends primary safety belt laws over secondary enforcement laws to reduce motor vehicle-related injuries and deaths.

Intervention

Primary safety belt laws allow police to stop motorists solely for being unbelted. Secondary safety belt laws only allow police to ticket unbelted motorists if they have been stopped for other reasons, such as speeding.

CPSTF Finding and Rationale Statement

Read the CPSTF finding pdf icon [PDF - 135 kB].

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What the CPSTF Found

About The Systematic Review

The CPSTF finding is based on evidence from a systematic review of 13 studies (search period through June 2000).

The review was conducted on behalf of the CPSTF by scientists from CDC’s Division of Unintentional Injury Prevention with input from a team of specialists in systematic review methods and experts in research, practice and policy related to motor vehicle injury prevention.

Context

As of June 2017, 34 states, the District of Columbia, American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the Virgin Islands have primary safety belt laws for front seat occupants, and 15 states have secondary safety belt laws for front seat occupants. Current figures are available from the Governors Highway Safety Administration External Web Site Icon .

Summary of Results

Detailed results from the systematic review are available in the published evidence review [PDF - 2.85 MB].

The systematic review included 13 studies.

Nine studies compared states with primary laws to states with secondary laws.
Four studies evaluated the effect of changing from secondary to primary laws.
Fatal injuries decreased by a median of 8% in primary law states versus secondary law states (5 studies).
Observed seat belt use increased by a median of 14 percentage points in primary law states versus secondary law states (5 studies).
Police-reported safety belt use could not be calculated (1 study).
Self-reported safety belt use could not be calculated (2 studies)

Summary of Economic Evidence

An economic review of this intervention did not find any relevant studies.

Applicability

These findings should be applicable to all U.S. drivers and passengers.

Evidence Gaps

Additional research and evaluation are needed to answer the following questions and fill existing gaps in the evidence base. (What are evidence gaps?)

What are the age, gender, and racial differences between violators in primary and secondary law states?
Are primary enforcement laws more or less effective in certain populations?
Do primary safety belt laws increase or decrease risky driving?
Do primary laws or enhanced enforcement programs deter alcohol-impaired driving?
Are primary laws associated with changes in frequency of traffic stops for ethnic and racial minorities relative to the general population?
What are the cost-benefit, cost utility, and cost-effectiveness of interventions to increase safety belt use?
How can communities increase public acceptance of primary safety belt laws?

Study Characteristics

All of the included studies compared laws in the United States.
- Studies compared states with primary laws to those with secondary laws (9 studies), or evaluated the effect of changing from a secondary to a primary law (4 studies). There were no studies of states changing from a primary law to a secondary law.
Studies were conducted in 49 states and the District of Columbia and looked at drivers and passengers of all ages.
Reported outcomes included fatal injuries, observed safety belt use, police-reported safety belt use, and self-reported safety belt use.

Publications

Dinh-Zarr TB, Sleet DA, Shults RA, et al. Reviews of evidence regarding interventions to increase use of safety belts. American Journal of Preventive Medicine. 2001;21(4S):48-65.

Task Force on Community Services. Recommendations to reduce injuries to motor vehicle occupants: increasing child safety seat use, increasing safety belt use, and reducing alcohol-impaired driving. American Journal of Preventive Medicine. 2001;21(4S):16-22.

Zaza S, Carande-Kulis VG, Sleet DA, et al. Methods for conducting systematic reviews of the evidence of effectiveness and economic efficiency of interventions to reduce injuries to motor vehicle occupants. American Journal of Preventive Medicine. 2001;21(4S):23-30.

Centers for Disease Control and Prevention. Motor-vehicle occupant injury: strategies for increasing use of child safety seats, increasing use of safety belts, and reducing alcohol-impaired driving. MMWR. 2001;50(RR-7):1-13. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5007a1.htm.

Shults RA, Elder RW, Sleet DA, Thompson RS, Nichols JL. Primary enforcement seat belt laws are effective even in the face of rising belt use rates. Accident Analysis and Prevention. 2004;36:491-3. Available at: http://www.sciencedirect.com/science/article/pii/S0001457503000381.

Shults RA, Nichols JL, Dinh-Zarr TB, Sleet DA, Elder RW. Effectiveness of primary enforcement safety belt laws and enhanced enforcement of safety belt laws: a summary of the Guide to Community Preventive Services Systematic Reviews. Journal of Safety Research. 2004;35:189-96. Available at: http://www.sciencedirect.com/science/article/pii/S0022437504000234.

Sleet DA, Branche CM. Road Safety is No Accident. Proceedings from a Symposium on High Visibility Enforcement - Building Sustained Safety Belt Use. Journal of Safety Research. 2004;35(2):173-4. Available at: http://www.sciencedirect.com/science/article/pii/S0022437504000295.

Zaza S, Sleet DA, Elder RW, Shults RA, Dellinger A, Thompson RS. Response to letter to the editor. American Journal of Preventive Medicine. 2002;22:330-1.

Sleet DA. Evidence based injury prevention: guidance for community action. In: Australian Third National Conference on Injury Prevention and Control. Australian Third National Conference on Injury Prevention and Control. Brisbane, Queensland, Australia; 1999.

Miller TR. The effectiveness review trials of Hercules and some economic estimates for the stables. American Journal of Preventive Medicine. 2001;21(4S):9-12.

Webb M. Research as an advocate's toolkit to reduce motor vehicle occupant deaths and injuries. American Journal of Preventive Medicine. 2001;21(4S):7-8.

Waller PF. Public health's contribution to motor vehicle injury prevention. American Journal of Preventive Medicine. 2001;21(4S):3-4.

Satcher D. Note from the Surgeon General. American Journal of Preventive Medicine. 2001;21(4S):1-2.

Novick LF, Kelter A. Guide to Community Preventive Services: a public health imperative. American Journal of Preventive Medicine. 2001;21(4S):13-15.

Moffat J. Motor vehicle occupant injury prevention: the states' perspective. American Journal of Preventive Medicine. 2001;21(4S):5-6.

Task Force on Community Services, Zaza S, Briss PA, Harris KW. Motor vehicle occupant injury. In: The Guide to Community Preventive Services: What Works to Promote Health?. The Guide to Community Preventive Services: What Works to Promote Health? Atlanta (GA): Oxford University Press; 2005:329-84.

Supporting Materials

Analytic Framework

Analytic Framework pdf icon [PDF - 2.85 MB] – see Figure 1 on page 49

Summary Evidence Table

Summary Evidence Table pdf icon [PDF - 2.85 MB] – see Appendices 1 and 2, pages 61- 65

Included Studies

The number of studies and publications do not always correspond (e.g., a publication may include several studies or one study may be explained in several publications).

Campbell BJ. The association between enforcement and seat belt use. J Safety Res 1988;19:150–63.

Escobedo LG, Chorba TL, Remington PL, Anda RF, Sanderson L, Zaidi AA. The influence of safety belt laws on self-reported safety belt use in the United States. Accid Anal Prev 1992;24:643–53.

Evans WN, Graham JD. Risk reduction or risk compensation? The case of mandatory safety-belt use laws. J Risk Uncertainty 1991;4:61–73.

Fielding JE, Knight KK, Goetzel RZ. The impact of legislation on self-reported safety belt use in a working population. J Occup Med 1992;34:715–7.

Houston DJ, Richardson LE, Neeley GW. Legislating traffic safety: a pooled time series analysis. Soc Sci Q 1995;76:328–45.

Houston DJ, Richardson LE, Neeley GW. Mandatory seat belt laws in the states: a study of fatal and severe occupant injuries. Eval Rev 1996;20:146–59.

Lange JE, Voas RB. Nighttime observations of safety belt use: an evaluation of California’s primary law. Am J Public Health 1998;88:1718–20.

Preusser DF, Preusser CW. Evaluation of Louisiana’s safety belt law change to primary enforcement. Washington, DC: U.S. Department of Transportation, National Highway Traffic Safety Administration, 1997. DOT HS 808 620.

Solomon MG, Nissen WJ. Evaluation of Maryland, Oklahoma, and the District of Columbia’s seat belt law change to primary enforcement. Washington, DC: U.S. Department of Transportation, National Highway Traffic Safety Administration, 2000. DOT HS 809 213.

Ulmer RG, Preusser CW, Preusser DF, Cosgrove LA. Evaluation of California’s safety belt law change from secondary to primary enforcement. J Safety Res 1995;26:213–20.

Wagenaar AC, Maybee RG, Sullivan KP. Mandatory seat belt laws in eight states: a time-series evaluation. J Safety Res 1988;19:51–70.

Winnicki J. Safety belt use laws: evaluation of primary enforcement and other provisions. Washington, DC: U.S. Department of Transportation, National Highway Traffic Safety Administration, 1995. DOT HS 808 324.

Additional Materials

There is no information for this section.

Search Strategies

The following outlines the search strategy used for reviews of these interventions to increase use of safety belts: Laws Mandating Use; Primary (vs. Secondary) Enforcement Laws; Enhanced Enforcement Programs.

The reviews of interventions to reduce motor vehicle-related injury reflect systematic searches of multiple databases as well as reviews of reference lists and consultations with experts in the field. The team searched six computerized databases (MEDLINE, Embase, Psychlit, Sociological Abstracts, EI Compendex, and Transportation Research Information Services [TRIS]), which yielded 10,958 titles and abstracts for articles, book chapters, reports, and published papers from the Association for the Advancement of Automotive Medicine proceedings about safety belts, alcohol-impaired driving or child passenger safety. Studies were eligible for inclusion if:

They were published from the originating date of the database through June 2000 (March 1998 for child safety seat interventions)
They involved primary studies, not guidelines or reviews
They were published in English
They were relevant to the interventions selected for review
The evaluation included a comparison to an unexposed or less-exposed population
The evaluation measured outcomes defined by the analytic framework for the intervention

Search Strategy for Use of Safety Belts:

(MOTOR(W)VEHICLE?) OR AUTOMOBILE? OR CAR OR CARS OR TRUCK? OR (TRAFFIC(2N)(ACCIDENT? OR CRASH? OR DEATH? OR FATALIT? OR INJUR?))

AND

(SEAT(W)BELT?) OR SEATBELT? OR (SAFETY(W)RESTRAINT?) OR (SAFETY(W)BELT?) OR (OCCUPANT(W)RESTRAINT?) OR OCCUPANT(W)PROTECTION)

AND

INTERVENTION? OR OUTREACH? OR PREVENTION OR (COMMUNITY(3N)(RELATION? OR PROGRAM? OR ACTION)) OR DETERRENT? OR PROGRAM? OR LEGISLATION? OR LAW? OR EDUCATION OR DETERRENCE OR COUNSELING OR CLASS OR CLASSES OR TRAINING OR PROMOTION? OR BEHAVIOR?

NOT

PEDESTRIAN? OR MOTORCYCLE OR BICYCL? OR CYCLIST? OR (SCHOOL(W)BUS?) OR BUS OR BUSES OR AIRPLANE? OR AIR(W)TRANSPORTATION?) OR AVIATION? OR (AIR(W)TRAFFIC) OR (AIR(W)CRAFT) OR DIAGNOSIS OR THERAPY OR GUIDELINE OR COMMENT? OR HISTORY OR EDITORIAL

Review References