Rg. Ulmer et al., EVALUATION OF CALIFORNIA SAFETY BELT LAW CHANGE FROM SECONDARY TO PRIMARY ENFORCEMENT, Journal of safety research, 26(4), 1995, pp. 213-220
Some states allow an officer to stop a vehicle for an observed belt la
w violation alone (primary). Most require that the initial stop be mad
e for some other violation before a belt law citation can be issued (s
econdary). On January 1, 1993, California became the first state to im
plement an uninterrupted change from secondary to primary belt law enf
orcement. In six study communities, the percentage of drivers observed
wearing seat belts increased from 58% prior to the law change to 76%
soon thereafter. Drivers surveyed at DMV offices indicated that they h
ad knowledge of the new law and were more likely to wear their belts n
ow than in the past.