The effects of mandatory seat belt laws on motor vehicle fatalities in the United States

Objective. This article assesses the effectiveness of mandated seat belt usage. The theory of offsetting behavior asserts that when drivers feel safer, they compensate by driving less cautiously. As a consequence, any lifesaving effects from mandated safety devices such as seat belts could be significantly diminished or entirely offset. Method. This article uses regression analysis and two years (1988 and 1997) of state-level data to test for the presence of offsetting behavior by estimating models explaining total and nonoccupant motor vehicle deaths. In addition to accounting for several factors generally acknowledged as being determinants of highway deaths, the models control for the impact of primary and secondary seat belt laws. Results. The Findings suggest the existence of offsetting behavior by drivers of motor vehicles. Conclusions. We need to recognize the probability of such compensatory behavior and direct our efforts at ways of ameliorating the adverse effects.