The findings in this report are subject to at least six limitations. First, NEISS-AIP provides data at the national level but prevents examination of injury estimates by state. The injury estimates reported likely are underestimates of all nonfatal motor vehicle—occupant injuries because NEISS-AIP does not include physician offices, clinics, urgent-care facilities, or any medical facilities other than hospital emergency departments. Additionally, NEISS-AIP does not collect factors that might relate to the injuries, such as seating position, seat belt use, air bag deployment, or whether injuries occurred in states with primary or secondary enforcement laws. Second, 2008 BRFSS was a landline telephone survey, and as such, excluded a small percentage of households with no telephone and approximately 15% of households with wireless telephones only. Third, the BRFSS response rate was only 53%. Fourth, the BRFSS data are self-reported; however, a recent evaluation of self-reported data on seat belt use found little evidence of overestimation of use because of social desirability bias.15 Fifth, the analysis did not consider other components of enforcement laws that might affect seat belt use (e.g., amount of fine, whether all occupants or only those in the front seat are covered, and the length of time law has been in effect). Finally, the data presented from both surveillance systems are cross-sectional and cannot be used to assess causality regarding seat belt enforcement laws, seat belt use, and nonfatal injuries.