An evaluation of the effectiveness of motor cycle daytime headlight laws.

Currently, 17 states mandate the daytime use of motorcycle headlights. The purpose of these laws is to make the motorcyclists more conspicuous and reduce the number of daytime multi-vehicle collisions. The effectiveness of the laws is examined by comparing the proportion of daytime fatal, front, and side-angle collisions between states with and without such laws. The comparison is based on all motorcycle fatalities recorded by NHTSA for the years 1975-80. The analysis shows no statistically significant difference between states with and without such laws, suggesting that daytime headlight laws are ineffective. Several explanations of this negative finding are explored.