Primary Seat Belt Laws and Offsetting Behavior: Empirical Evidence from Individual Accident Data.

According to the offsetting effect theory, since drivers wearing seat belts feel more secure, they tend to drive less carefully and may cause more accidents, including those involving pedestrians. Most previous studies have used only state-level accident data, which cannot control for individual characteristics of drivers, vehicles, and the environmental factors surrounding the accidents. This paper uses individual-level accident data to analyze how drivers respond to the laws exploiting changes in the seat belt laws in a number of US states in the last decade. I find that the laws do not cause less careful behavior by drivers. In fact, they drive more carefully when more stringent seat belt laws are in effect, and this leads to less involvement of pedestrians in accidents. These results show that the offsetting effects do not exist when all accidents, including fatal accidents, are considered.