Traffic safety laws are on the books in every state to reduce deaths and injuries in crashes by changing driver behavior. The idea is to deter dangerous behavior like driving while impaired by alcohol and encourage beneficial habits like buckling safety belts.
How do these laws compare from state to state? Overall the strongest laws in the United States are in California, the District of Columbia, and Maryland. The weakest traffic safety laws are those in Montana, South Carolina, and South Dakota.
Research has repeatedly shown the benefits of good traffic safety laws that are enforced. This has been established as the only way to achieve high belt use rates, for example. The starting point is to put a good law on the books, which is why the Institute has conducted a comprehensive assessment of key traffic safety laws in all 50 states and the District of Columbia.
"We didn't evaluate every law by any stretch," says Institute senior vice president Allan Williams. "We looked at provisions of selected laws that research shows have improved driver behavior. Clearly some states do a better job than others of getting good traffic safety laws on the books."
Even if a law includes strong provisions, enacting it isn't sufficient to influence the behavior of many drivers. The necessary next step to maximize a law's effectiveness is to publicize and enforce it. "People don't usually comply with traffic laws because they think doing so will prevent crashes or save lives. People comply if they believe there's a real chance of getting a ticket or points on their license if they don't. This is why we didn't give high marks to laws that are on the books but are hard to enforce," Williams explains.
Institute researchers assessed alcohol-impaired driving laws, young driver licensing laws, safety belt use laws, child restraint use laws, motorcycle helmet use laws, and laws allowing camera enforcement of red light violations. A rating of good, acceptable, marginal, or poor is assigned to each law, or set of related laws, in each state. These ratings reflect how well the provisions of a given law can be expected to improve safety, based on research identifying what works and doesn't work to achieve such improvements.
"There used to be a lot of high-profile activity to reduce alcohol-impaired driving. But lately people seem to believe we've solved this problem, so the push to strengthen laws and enhance enforcement has waned," Williams says. The Institute has evaluated four separate DUI/DWI laws in all states and the District of Columbia.
- Under administrative license revocation laws, the license of every driver arrested for DUI/DWI is automatically revoked for a specified time. The success of such laws in reducing fatal crashes has been documented since the late 1980s (see "New laws to curb drinking drivers save many lives," March 14, 1988). The best administrative license revocation laws require driver's license removal for at least 30 days with few or no exceptions for hardship. "Administrative license revocation is the cornerstone of an effective DUI or DWI program," Williams says. Yet Kentucky, Michigan, Montana, New Jersey, Pennsylvania, Rhode Island, South Carolina, South Dakota, and Tennessee still don't have such laws on the books. Another 17 states don't require revocations lasting at least 30 days.
- Under the laws in 21 jurisdictions, it's illegal to drive with a blood alcohol concentration, or BAC, at or above 0.08 percent (elsewhere it's usually 0.10 percent). Research indicates that 0.08 laws have reduced fatal crashes in which alcohol is a factor.
- Across the United States, it's illegal for people younger than 21 to drive with any measurable BAC. All jurisdictions have such laws, dubbed zero tolerance, because in 1998 the federal government began withholding highway funds from states without the provisions. But the laws are far easier to enforce in some states than others. Institute researchers found that laws in Massachusetts, Nevada, New Jersey, New Mexico, North Dakota, Rhode Island, and Tennessee are virtually unenforceable because police must suspect a young driver has a high BAC before administering a breath test to check for violations of the zero tolerance law, under which any measurable BAC constitutes a violation (see Zero-tolerance enforcement varies among states, March 11, 2000).
- High-profile sobriety checkpoints are effective ways to deter alcohol-impaired driving. They increase drivers' perceptions that apprehension is likely to follow the offense. Yet checkpoints aren't permitted in Idaho, Iowa, Michigan, Minnesota, Montana, Oregon, Rhode Island, Texas, Washington, Wisconsin, or Wyoming.
Graduated licensing laws
The newest drivers are the most hazardous because they're not only inexperienced but also immature. Teenage drivers have the highest crash risk of any group, and 16 year-olds pose a much greater risk than older teens. This is why graduated licensing is being embraced by state legislators. Its purpose is to protect beginners by phasing in full driving privileges so teenagers graduate to unrestricted licenses over at least a year (see "Delayed licensure in Connecticut leads to crash reductions," March 11, 2000).
Beginning with Florida in 1996, "graduated licensing has caught on rapidly," Williams points out. "An impetus has been media attention on young driver crashes, especially fatal crashes. This attention has kept the issue in the forefront and helped make state legislators receptive to graduated licensing."
Now only nine states (Alabama, Arizona, Hawaii, Kansas, Montana, Nevada, Oklahoma, Texas, and Wyoming) fail to include any of the key provisions of graduated licensing. In the other 42 jurisdictions, there's wide variation in the strength of the provisions.
Williams explains that "the most important aspect of graduated licensing is to restrict driving once a beginner gets a license.
States accomplish this by prohibiting unsupervised driving in high-risk situations like at night or with passengers. The tougher these restrictions are and the longer they last past a beginner's 16th birthday, the higher we rated a state's licensing law covering young drivers. Also important is an initial learning phase lasting six months or longer when only driving under supervision is allowed."
Safety belt use laws
In 1984, New York enacted the nation's first law requiring motorists to buckle up. Within 2 years, 22 jurisdictions had such laws, and now all but New Hampshire does. But the provisions vary widely.
For example, most states still don't allow police to stop motorists solely for belt violations (primary enforcement). Enforcement is secondary, which means motorists have to be stopped for some other violation first. This impedes enforcement and explains, in part, why belt use is significantly lower in the United States than in Canada and elsewhere. The laws in only 17 U.S. states and the District of Columbia allow primary enforcement, and even in these states the laws don't always cover people riding in rear seats.
"One thing we know from repeated research conducted since the early 1980s is that belt law effectiveness depends on publicity and enforcement," Williams says (see "New record: Small city in upstate N.Y. achieves 90 percent belt use," Jan. 15, 2000). "It's harder to enforce a secondary law. This is why, when we rated state belt use laws, we considered whether the provisions for enforcement are primary or secondary. We also considered whether all occupants are covered."
Child restraint laws
To evaluate these, the Institute assessed not only the comprehensiveness of state laws covering very young children but also the adequacy of adult belt laws, which cover older children. What matters most is whether these laws together provide primary coverage for all children younger than 13 in all seats or allow some children to ride unrestrained.
For example, children too old to be covered under the child restraint laws in 14 states are protected by adult belt laws that apply only to people riding in the front seat. Thus, it's perfectly legal for children to ride unrestrained in rear seats.
"This makes no sense," Williams says. "The back seat is where we tell parents it's safest for their children to ride, so restraint laws should cover the kids who sit there."
Motorcycle helmet use laws
By the 1970s, helmet laws had been enacted in virtually all states. All riders were covered, and injuries among cyclists were reduced. (Wearing a helmet reduces the risk of death in a motorcycle crash by about one-third). But by 1980 most states had abandoned their motorcycle helmet laws or substantially weakened them by applying them only to riders younger than a specified age, usually 18.
Now all riders are covered in only 21 jurisdictions. Helmet laws aren't on the books in Colorado, Illinois, or Iowa, and they're watered down in another 27 states.
"You might as well not have a law that doesn't apply to all riders," Williams says, "because so few motorcyclists are the younger riders covered under the weak laws. Helmet use rates in states with limited laws are about the same as in states without any laws at all" (see "Without a motorcycle helmet there's no easy ride," April 4, 1998). For this reason, the Institute assigned poor ratings to the laws in all states where helmet laws don't apply to all riders.
Red light camera enforcement
Running red lights is a good example of "everyday" aggressive driving. It's less spectacular but a lot more common than the occasional headline-grabbing instances of aggressive driving known as road rage.
Until a few years ago, red light violators had to be apprehended and ticketed one by one. The odds of this were so small that offenders found little reason to change their ways. But now they do, at least where red light cameras have been installed to snap photos of vehicles whose drivers deliberately run red lights. Then the violators are ticketed by mail.
Such programs reduce red light running by about 40 percent (see "Red light running crashes increase," July 11, 1998), but there's a problem. Relatively few red light camera programs are operational, in many cases because state laws haven't been enacted to authorize them. In only six jurisdictions (California, Colorado, Delaware, the District of Columbia, Hawaii, and Maryland) is camera enforcement specifically authorized for use statewide.
"Cameras shouldn't merely be permitted in the United States. They should be in wide use, as in other countries," Williams says. "Red light running kills hundreds of people every year, more than half of them struck by the signal violators. To make a dent in this toll, we've got to encourage the use of the camera technology we know will deter the would-be violators."