All states now have zero-tolerance laws prohibiting people younger than 21 from driving with any positive blood alcohol concentration (BAC). Congress made zero tolerance a national standard back in 1995, passing a law to withhold highway funds from states that didn't comply by October 1, 1998.
But zero-tolerance laws aren't the same everywhere, and enforcement varies. A new Institute study shows that provisions in some states make it easier to issue charges when a zero-tolerance offender is identified. But across the country, these laws have done little to change how police identify underage drinking drivers.
Researchers reviewed zero-tolerance laws in all 50 states and identified 5 — California, Michigan, New Mexico, New York, and Virginia — with laws that appear to differ in how easily they can be enforced. Police in these states were interviewed and asked to describe their zero-tolerance enforcement practices.
California's zero-tolerance law stands out as one of the easiest to enforce, primarily because police can use the results from preliminary breath tests administered at the roadside as evidence of zero-tolerance violations. In most other states, evidential tests are required. This means a driver must be detained or taken into custody and transported to a facility for testing — a time-consuming step that can impede enforcement.
In some states where evidential tests are required, there are further obstacles. Drivers in New Mexico can be tested only if they are suspected of DWI, so a zero-tolerance citation can result only indirectly — for example, when a suspected underage DWI offender's BAC is below the legal limit by the time the test is given.
New York and California represent extremes in the amount of required paperwork. Both issue administrative license suspensions to zero-tolerance offenders, but in New York the paperwork is so lengthy that police find enforcement rarely is worthwhile. In contrast, police in California use a streamlined form.
"Police have many priorities and limited time. They're more likely to spend their time on enforcement they feel is most productive," says Institute research vice president Susan Ferguson. "California's zero-tolerance law respects these constraints, so police are more likely to enforce it."
Detection is a common problem
The detection of offenders is a universally weak link in enforcement. The procedures to find underage drivers with low BACs are no different from procedures to find DWI offenders with higher BACs. Police stop drivers who show signs of driving impairment or violate traffic laws. Then the officers look for behavioral or environmental cues to determine alcohol use.
Because young drivers with low BACs may not show signs of impairment, they can easily escape detection both on the road and during routine traffic stops. Add the fact that underage youths don't always drink where regular patrols would find them, and the chances of detection get even slimmer. Those who are identified usually have higher BACs and are cited for DWI, not zero tolerance.
Risks warrant enforcement
Detection is difficult, but no less critical. "Underage drivers with low BACs may drive well enough to elude detection, but that doesn't mean they aren't a danger on the road," Ferguson says. "In fact, studies show young drivers are much more at risk of a fatal crash than older drivers with the same blood alcohol concentration."
To increase the chances of detecting zero-tolerance violators, police patrols and sobriety checkpoints should be conducted close to where underage people drink. By increasing the perception of enforcement, high-visibility efforts like checkpoints also serve to deter would-be offenders. Unfortunately, researchers have found that police don't often use these strategies.