1.1 State Primary Enforcement Belt Use Laws
Primary enforcement belt use laws permit non-users to be stopped and cited independently of any other traffic behavior. Secondary enforcement laws allow non-users to be cited only after they first have been stopped for some other traffic violation.
Use: As of July 2005, 22 States and the District of Columbia had primary belt use laws, 27 States had secondary enforcement laws, and New Hampshire had no belt use law applicable to adults (Glassbrenner, 2004c, NHTSA, 2005b). Some of the secondary laws are primary for drivers under a specified age.
Effectiveness: In 2004, belt use averaged 85 percent in the 21 primary law States and the District of Columbia and averaged 75 percent in the 28 secondary law States (Glassbrenner, 2004c). Studies of five States that changed their belt use laws from secondary to primary enforcement found that belt use increased from 12 to 18 percentage points where all passenger vehicles were covered by the law and 8 percentage points in one State where pickup trucks were excluded (Nichols, 2002). CDC's systematic review of 13 high-quality studies (Shults et al., 2004) found that primary laws increase belt use by about 14 percentage points and reduce occupant fatalities by about 8 percent compared to secondary laws.
Costs: Once legislation has been enacted to upgrade a secondary law to primary, the costs are to publicize the change and enforce the new law. Publicity costs to inform the public of the law change should be low because the media will cover the law change extensively. Law enforcement can adapt its secondary law enforcement strategies for use under the primary law or may be able to use new strategies permitted by the primary law. States wishing to increase enforcement and publicity to magnify the effect of the law change will incur additional costs: see Chapter 2, Section 2.1.
Time to implement: A primary belt use law can be implemented as soon as the law is enacted.