New York enacted the first statewide mandatory seat belt law in 1984. Now 49 states have some form of law requiring drivers and passengers to buckle up, and shows that they are having the desired effect. More and more motorists are wearing their belts.

There are two types of seat belt enforcement: primary and secondary. The District of Columbia and 21 states have primary seat belt laws that permit officers to stop a driver merely for a seat belt violation. Another 28 states have secondary laws that allow officers to cite motorists for not wearing a seat belt during a stop for another violation.

Research by the University of Missouri-Columbia shows that both types of laws have persuaded motorists to buckle up. However, as one would expect, the research confirmed that primary laws are more effective.

“Because primary enforcement increases the chance of receiving a citation for failure to obey the law, such laws enhance seat belt use,” says Lilliard Richardson, an associate professor at MU’s Truman School of Public Affairs.

Richardson’s research also found, not surprisingly, that the higher the fine for failure to obey the law the greater compliance among motorists. The average fine in 2004 (the last year studied) was $25. However, some states impose much greater fines. Texas, for example, assesses $200 for a first offense.

Other states impose less than a slap on the wrist and have achieved less than spectacular results. Arizona, Kansas, Missouri, Pennsylvania, South Carolina, Tennessee, and Wisconsin are all secondary enforcement states that charge only a $10 fine per violation. In 2002 average seat belt use in these states was only 68.4 percent. Richardson estimates that if these states adopted primary enforcement laws and increased the fine to $50, seat belt use would increase 15 percent.

“This study’s findings hold two obvious implications for public policy,” Richardson says. “First, states with secondary enforcement statutes should upgrade to primary enforcement. Second, imposing fines of at least $25 for violating a seat belt law would enhance seat belt use in many states, and increasing fines to $50 would yield even greater seat belt use.”