In every U.S. jurisdiction drivers younger than 21 may be arrested if they have any measurable alcohol in their blood, not just if it's enough to arrest them under DWI laws. Prompted by the threat of federal sanctions, state legislators put these zero tolerance laws on the books, but the results vary from state to state. Those in Washington are impressive.
An Institute study found 51 percent more arrests of 16-20-year-old drivers for alcohol violations in Washington state after the zero tolerance law took effect in 1994, compared with before. The biggest arrest increase was among young people who weren't driving illegally under the state's DWI law but did have measurable alcohol (0.02 percent or more) in their blood. Arrests more than doubled of drivers with BACs of 0.02-0.079 percent (the threshold for DWI is 0.08 in Washington and every other state). This increase is important because, while young drivers aren't as likely as older people to drink and drive, their crash risks increase more when they do, even at low BACs.
Results for recidivism aren't as impressive. More than 1 of 4 of the drivers younger than 21 who were arrested for alcohol violations in Washington state subsequently were arrested again. Those with higher BACs (0.10 percent or more) at the first arrest were even more likely to commit second offenses.
Drivers in Washington may be tested based on suspicion of violating either the DWI or the zero tolerance law. However, the policies in many other states aren't as strong. At the extreme is New Mexico, where the zero tolerance law is practically unenforceable (see "Many teens are unaware of zero tolerance laws," June 30, 2001). Young drivers are subject to testing only if they're suspected of DWI. Once tested, a driver may be charged under zero tolerance if the BAC is lower than 0.08 but still at least 0.02 percent. This reduces the chances that police will stop and arrest underage drivers to begin with.
Even in states like California, with its strong zero tolerance law, enforcement may not be a priority. Reasons aren't clear, but it could be that this simply isn't considered a serious offense. Whatever the reasons, lax enforcement has contributed to limited awareness of zero tolerance laws.