Expected Beneficial Outcomes (Rated)
Increased seat belt use
Reduced fatal and non-fatal injuries
Evidence of Effectiveness
There is strong evidence that primary seat belt enforcement laws increase the use of seat belts1. Primary enforcement laws increase seat belt use and reduce fatal and non-fatal injuries more effectively than secondary enforcement laws1.
States that change from secondary to primary seat belt enforcement laws have increased rates of seat belt use after primary enforcement laws go into effect3. Changing from secondary to primary enforcement has been shown to increase seat belt use during the day and night4. Primary enforcement laws appear to have the largest effects among high-risk drivers, such as alcohol-impaired drivers, and among populations with lower rates of seat belt use, such as blacks and Hispanics3.
Despite concern, there is no evidence that minorities are stopped at higher rates than whites for seat belt violations in states with primary enforcement laws. Several states have added anti-harassment language to their primary seat belt laws to reduce the risk of such differential enforcement3.
Primary law enforcement can include paid media efforts5, 6. Primary seat belt laws that are enforced with well-publicized seat belt use checkpoints appear to yield more benefits through quality adjusted life years (QALYs) saved and injuries prevented than they cost to implement7.
Impact on Disparities
As of May 2015, 34 states and Washington, DC have primary seat belt laws for front seat occupants; in 17 of these states and Washington, DC, primary enforcement laws also cover rear seats8.
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1 CG-Motor vehicle injury - The Guide to Community Preventive Services (The Community Guide). Motor vehicle injury prevention.
2 NHTSA-Goodwin 2013 - Goodwin A, Sandt B, Hall W, Thomas L, O’Brien N, Summerlin D. Countermeasures that work: A highway safety countermeasure guide for state highway safety offices, 7th edition. Washington, DC: National Highway Traffic Safety Administration (NHTSA), US Department of Transportation (US DOT); 2013.
3 Dihn-Zarr 2001 - Dihn-Zarr TB, Sleet DA, Shults RA, et al. Reviews of evidence regarding interventions to increase the use of safety belts. American Journal of Preventive Medicine. 2001; 21(4S):48-65.
4 NHTSA-Chaudhary 2010 - Chaudhary NK, Tison J, Casanova T. Evaluation of Maine's seat belt law change from secondary to primary enforcement (Report No. DOT HS 811 259). Washington DC: National Highway Traffic Safety Administration (NHTSA), US Department of Transportation (US DOT); 2010.
5 NHTSA-Nichols 2010 - Nichols J, Tippetts AS, Fell J, et al. Strategies to increase seat belt use: An analysis of levels of fines and the types of law. Washington DC: National Highway Traffic Safety Administration (NHTSA), US Department of Transportation (US DOT); 2010.
6 NHTSA-Hedlund 2008 - Hedlund J, Gilbert SH, Ledingham K, Preusser D. How states achieve high seat belt use rates. Washington DC: National Highway Traffic Safety Administration (NHTSA), US Department of Transportation (US DOT); 2008.
7 Miller 2000* - Miller TR, Levy DT. Cost-outcome analysis in injury prevention and control: Eighty-four recent estimates for the United States. Medical Care. 2000;38(6):562-82.
8 GHSA-Seat belt laws - Governors Highway Safety Association (GHSA). Seat belt laws.
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