Intervention Fact Sheets
Primary Enforcement of Seat Belt Laws
Primary enforcement [of seat] belt use laws permit seat belt use law violators to be stopped and cited independently of any other traffic behavior. Secondary enforcement laws allow violators to be cited only after they first have been stopped for some other traffic violation. (UNC Highway Safety Research Center, 2011, p. 2-13)
All new passenger cars had some form of seat belts beginning in 1964, shoulder belts in 1968, and integrated lap and shoulder belts in 1974 ([Automotive Coalition for Traffic Safety (ACTS)], 2001). Few occupants wore the belts: surveys in various locations recorded belt use of about 10 percent. The first widespread survey, taken in 19 cities in 1982, observed 11 percent belt use for drivers and front-seat passengers ([Williams and Wells, 2004]). (UNC Highway Safety Research Center, 2011, p. 2-4)
“New York enacted the first belt use law in 1984. Other States soon followed. In a typical State, belt use rose quickly to about 50 percent shortly after the State’s belt law went into effect” (UNC Highway Safety Research Center, 2011, p. 2-4). By 1996, every state, with the exception of New Hampshire, had a mandatory seat belt use law covering drivers and front-seat occupants.
“As of July 2010, 31 States and the District of Columbia had primary belt use laws, 18 States had secondary enforcement laws, and New Hampshire had no belt use law applicable to adults (IIHS, [undated])” (UNC Highway Safety Research Center, 2011, p. 2-13). Seat belt laws vary by whether they cover front-seat occupants only or include rear-seat occupants as well. In a few states, seat belt use is a secondary law for drivers and passengers older than a specified age (varies by state) but a primary law for younger passengers.
In 2009, belt use averaged 88 percent in the 30 States with primary seat belt laws at that time and the District of Columbia and averaged 77 percent in those with weaker enforcement laws ([Chen and Ye, 2010]). Studies of 5 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). The [Centers] for Disease Control and Prevention’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. In another study, Farmer and Williams (2005) found that passenger vehicle driver death rates dropped by 7 percent when States changed from secondary to primary enforcement. On average, States that pass primary seat belt laws can expect to increase seat belt use by eight percentage points. Depending on the level of high-visibility enforcement that they employ, however, far greater results are possible. (UNC Highway Safety Research Center, 2011, p. 2-13)
Recent research (Masten, 2007) has provided strong support that changing from secondary to primary enforcement [of] seat belt laws increases occupant seat belt use during the nighttime hours as well as the daytime hours when most observational surveys of seat belt use are conducted. (UNC Highway Safety Research Center, 2011, p. 2-13)
[Hedlund, Gilbert, et al., 2008] studied the effects of primary law changes on seat belt use and occupant fatalities in Michigan, New Jersey, Washington, Delaware, Illinois, and Tennessee. Strong evidence was found in the FARS data for all 6 States that primary seat belt laws increase seat belt use. Furthermore, statistically significant decreases in the number of front-seat passenger vehicle occupant fatalities were found in Michigan and Washington and the decrease in New Jersey was marginally significant. The lack of significant effects on fatalities in Illinois and Tennessee, as well as a marginal increase in Delaware, was attributed in part to the short amount of time since the implementation of the primary provisions in these States as well as the small number of fatalities in Delaware. (UNC Highway Safety Research Center, 2011, p. 2-13)
Chaudhary, Tison, and Casanova (2010) evaluated the effects of Maine’s change from secondary to primary enforcement of their seat belt law. Observational surveys conducted over an 18-month period after this change went into effect in 2007, measured increases in seat belt use from 77 to 84 percent during the daytime and from 69 percent to 81 percent at night. (UNC Highway Safety Research Center, 2011, p. 2-14)
L. Beck and West, 2011, used data from the nationally representative Behavioral Risk Factor Surveillance System (BRFSS) survey in 2008 to compare seat belt use. They found that 88.2 percent of adults living in states with primary enforcement of seat belt laws reported always wearing a seat belt, compared with 79.2 percent in states with secondary laws. Differences in seat belt use existed in certain sociodemographic categories, but usage rates were higher for each group in states with primary enforcement of seat belt laws.
L. Beck and West, 2011, also examined 2001–2009 motor vehicle occupant injury data from the National Electronic Injury Surveillance System—All Injury Program (NEISS-AIP). The data are at the national level and do not allow for comparisons between states with and without primary enforcement of seat belt laws but demonstrate a 15.6-percent decline in the injury rate from 1,193.8 injuries per 100,000 population in 2001 to 1,007.5 in 2009. During this time, 14 additional states passed primary seat belt laws. In addition to the lack of state-specific data, no information is available on other factors related to injury, such as seat belt use or seat position, and only injuries reported in hospital emergency departments are included, which would likely underestimate the number of injuries.
Traynor, 2009, examined correlations between recent changes in teen driving regulations, DWI laws, seat belt laws, and differences in traffic fatalities using 1999–2003 data from the 48 contiguous states. After controlling for numerous factors affecting crash fatality risk, such as weather conditions, law enforcement spending, and speed limits, he found that the per-mile fatality rate insignificantly decreased with increasing strictness of seat belt laws where a primary law for all occupants was most strict. The author suggested that this may be due to the model design, which accounts for the interaction between seat belt laws and driver alcohol restrictions.
Another recent study used data from the Ohio Crash Outcome Data Evaluation System (CODES) program to predict annual medical cost savings to Medicaid if Ohio were to experience a 10-percentage-point increase in seat belt usage by switching to a primary seat belt law (Conner, Xiang, and Smith, 2010). Using 2003 crash records and hospital data, the authors estimated the ten-year cumulative savings to Medicaid as approximately $91 million (in 2007 dollars, after inflation of health care costs). In this study, only Medicaid costs (which accounted for 20.6 percent of the medical costs due to hospitalizations from motor vehicle crashes) were considered, so total medical cost savings across all payer sources would be even greater.
The effectiveness of primary seat belt laws is measured in various ways. Seat belt use is the most common measure and can be captured through observational studies or self-reporting. The annual National Occupant Protection Use Survey (NOPUS) conducted annually by NHTSA estimates daytime seat belt use through direct observation at probabilistically sampled intersections during one month of the year. Other observational studies have examined front-seat occupants only and distinguished between nighttime and daytime use. Self-reported seat belt use is often defined as “always” using a seat belt in a motor vehicle, regardless of seat position. Occupant injuries, fatalities, and death rates from passenger-vehicle and light-truck crashes have also been used to measure seat belt law effectiveness. One study used regression analysis to estimate the effect of the severity of seat belt laws (least severe [no law or fines] to most severe [primary enforcement for all occupants]) on per-mile fatality rate, expressed as the ratio of total annual traffic fatalities to annual millions of vehicle-miles traveled (Traynor, 2009). Medical cost savings have also been used to calculate the effectiveness of primary enforcement of seat belt laws (Conner, Xiang, and Smith, 2010).
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. (UNC Highway Safety Research Center, 2011, p. 2-14)
“A primary belt use law can be implemented as soon as the law is enacted unless it has a delayed effective date” (UNC Highway Safety Research Center, 2011, p. 2-14).
Opposition to Primary Enforcement of Seat Belt Laws
In most States there is substantial opposition to changing a secondary law to a primary belt use law. Opponents claim that primary laws impinge on individual rights and provide opportunities for law enforcement to harass minority groups. Studies in several States have found that minority groups were ticketed at similar or lower rates than others after a primary law was implemented (Shults et al., 2004). When Michigan changed from a secondary to a primary law, harassment complaints were very uncommon both before and after the law change. The proportion of seat belt use citations issued to minority groups decreased under the primary law. In a telephone survey, the vast majority of people who actually received seat belt citations did not feel that they were singled out on the basis of race, age, or gender. However, some minorities and young drivers reported perceptions of harassment ([Eby, Kostyniuk, Molnar, et al., 2004]). (UNC Highway Safety Research Center, 2011, p. 2-14)
Effect on Low-Belt-Use Groups
Studies in States that changed their law from secondary to primary show that belt use increased across a broad range of drivers and passengers. In some States, belt use increased more for low-belt-use groups, including Hispanics, African-Americans, and drinking drivers, than for all occupants (Shults et al., 2004). (UNC Highway Safety Research Center, 2011, p. 2-14)
|State||Initial Effective Date||Primary Enforcement||Who Is Covered and in What Seats||Maximum Fine for First Offense|
|Ala.||July 18, 1991||Yes; effective December 9, 1999||15+ years in front seat||$25|
|Alaska||September 12, 1990||Yes; effective May 1, 2006||16+ years in all seats||$15|
|Ariz.||January 1, 1991||No||8+ years in front seat; 5 through 15 in all seats||$10|
|Ark.||July 15, 1991||Yes, effective June 30, 2009||15+ years in front seat||$25a|
|Calif.||January 1, 1986||Yes; effective January 1, 1993||16+ years in all seats||$20|
|Colo.||July 1, 1987||No||16+ years in front seat||$71|
|Conn.||January 1, 1986||Yes; effective January 1, 1986||7+ years in front seat||$15|
|Del.||December 12, 1985||Yes; effective October 1, 1997||16+ years in all seats||$50b|
|D.C.||January 1, 1992||Yes; effective June 30, 2003||16+ years in all seats||$25|
|Fla.||July 1, 1986||Yes; effective June 30, 2009||6+ years in front seat; 6 through 17 years in all seats||$30|
|Ga.||September 1, 1988||Yes; effective July 1, 1996||8 through 17 years in all seats; 18+ years in front seat||$15c|
|Hawaii||December 16, 1985||Yes; effective December 16, 1985||8 through 17 years in all seats; 18+ years in front seat||$45|
|Idaho||July 1, 1986||No||7+ years in all seats||$10|
|Ill.||January 1, 1988||Yes; effective July 3, 2003||16+ years in all seats (effective January 1, 2012)||$25|
|Ind.||July 1, 1987||Yes; effective July 1, 1998||16+ years in all seats||$25|
|Iowa||July 1, 1986||Yes; effective July 1, 1986||18+ years in front seat||$25|
|Kan.||July 1, 1986||Yes; effective 6/10/10 (secondary for rear-seat occupants >18)||14+ years in all seats||$60; no court costs: 14–17 years; $10/no court costs: 18+ years|
|Ky.||July 15, 1994||Yes; effective July 20, 2006||6 and younger and more than 50 inches in all seats; 7+ in all seats||$25|
|La.||July 1, 1986||Yes; effective September 1, 1995||13+ years in all seats||$25; $45 Orleans Parish|
|Maine||December 26, 1995||Yes; effective September 20, 2007||18+ years in all seats||$50|
|Md.||July 1, 1986||Yes; effective October 1, 1997 (secondary for rear-seat occupants; effective October 1, 2013)||16+ years in front seat||$25|
|Mass.||February 1, 1994||No||13+ years in all seats||$25d|
|Mich.||July 1, 1985||Yes; effective April 1, 2000||16+ years in front seat||$25|
|Minn.||August 1, 1986||Yes; effective June 9, 2009||7 and younger and more than 57 inches in all seats; 8+ in all seats||$25|
|Miss.||July 1, 1994||Yes; effective May 27, 2006||7+ years in front seat||$25|
|Mo.||September 28, 1985||No (yes for children <16)||16+ years in front seat||$10|
|Mont.||October 1, 1987||No||6+ years in all seats||$20|
|Neb.||January 1, 1993||No||18+ years in front seat||$25|
|Nev.||July 1, 1987||No||6+ years in all seats||$25|
|N.H.||Not applicable||No law||No law||No law|
|N.J.||March 1, 1985||Yes; effective May 1, 2000 (secondary for rear-seat occupants; effective January 20, 2011)||7 years and younger and more than 80 pounds; 8+ in all seats||$20|
|N.M.||January 1, 1986||Yes; effective January 1, 1986||18+ years in all seats||$25b|
|N.Y.||December 1, 1984||Yes; effective December 1, 1984||16+ years in front seat||$50e|
|N.C.||October 1, 1985||Yes; effective December 1, 2006 (secondary for rear-seat occupants)||16+ years in all seats||$25|
|N.D.||July 14, 1994||No||18+ years in front seat||$20|
|Ohio||May 6, 1986||No||8 through 14 in all seats; 15+ years in front seat||$30 driver/ $20 passenger|
|Okla.||February 1, 1987||Yes; effective November 1, 1997||13+ years in front seat||$20|
|Ore.||December 7, 1990||Yes; effective December 7, 1990||16+ years in all seats||$110|
|Pa.||November 23, 1987||No (yes for children <18 years) (effective December 24, 2011)||8 through 17 years in all seats; 18+ years in front seat||$10|
|R.I.||June 18, 1991||Yes; effective June 30, 2011||18+ years in all seats||$40|
|S.C.||July 1, 1989||Yes; effective December 9, 2005f||6+ years in all seats||$25|
|S.D.||January 1, 1995||No||18+ years in front seat||$20|
|Tenn.||April 21, 1986||Yes; effective July 1, 2004||16+ years in front seat||$50g|
|Texas||September 1, 1985||Yes; effective September 1, 1985||7 years and younger who are 57 inches or taller; 8+ years in all seats||$200|
|Utah||April 28, 1986||No (yes for children <19 years)||16+ years in all seats||$45|
|Vt.||January 1, 1994||No||18+ years in all seats||$25|
|Va.||January 1, 1988||No||18+ years in front seat||$25|
|Wash.||June 11, 1986||Yes; effective July 1, 2002||16+ years in all seats||$124|
|W.Va.||September 1, 1993||Yes; effective July 1, 2013||8+ years in front seat; 8 through 17 years in all seats||$25|
|Wis.||December 1, 1987||Yes; effective June 30, 2009||8+ years in all seats||$10|
|Wyo.||June 8, 1989||No||9+ years in all seats||$25 driverh/ $10 passenger|
SOURCE: IIHS, 2014d.
a Arkansas rewards belt use by reducing the fine for the primary violation by $10.
b This state assesses points for this violation.
c In Georgia, the maximum fine is $25 if the child is 6 to 18 years old.
d Drivers in Massachusetts may be fined $25 for violating the belt law themselves and $25 for each unrestrained passenger 12 to 16 years old.
e New York assesses points only if the passenger is under 16.
f Police are prohibited in South Carolina from enforcing seat belt laws at checkpoints designed for that purpose. However, seat belt violations may be issued at license and registration checkpoints to drivers cited for other offenses.
g Drivers 18 and older in Tennessee who choose not to contest the citation pay a $10 fine by mail or $20 for drivers who are 16 and 17 years old.
h Wyoming rewards belt use by reducing the fine for the primary violation by $10.