Sarah Kliff passes along new research suggesting that being a designated driver is “[e]asy in concept but apparently a bit difficult in execution”:
About one-third of designated drivers have at least one drink while carrying the title, according to a new paper in the Journal of Studies on Alcohol and Drugs. Twenty percent, breath tests showed, had a blood alcohol level higher than 0.05, enough to impair their driving skills. … As the researchers note, this study has limitations: It was done at a set of college bars with a relatively homogeneous population. It doesn’t speak to designated driving in other situations. Still, it does suggest that there’s at least a decent-sized segment of the population that doesn’t have a strict idea of what it means to be the designated driver.
J.K. Trotter notes the novelty of the “designated driver” concept as a possible explanation:
The concept of “designated driving” is actually a fairly recent invention — it originated in northern Europe before spreading to North America in the late 1980s, via Harvard’s famous Alcohol Project — so it’s conceivable that kinks still need to be worked out. But millions of Americans have been educated about the effects of alcohol, thanks in no small part to the lobbying power of Mothers Against Drunk Driving. Indeed, the Florida study’s authors suggest that their findings “identify the need for consensus across researcher, layperson, and communication campaigns that a [designated driver] must be someone who has abstained from drinking entirely.”
Nancy Shute explains why “not legally drunk” is a bad metric for DDs to use:
In Europe, a designated driver is widely considered to be the less inebriated driver, not an abstainer. And surveys of drivers in the U.S. have found that they think it’s fine for the designated driver to drink, as long as her or his blood alcohol level is below the legal limit.
But when people’s driving skills while drinking are tested in laboratories, they start getting messed up much earlier than many people think. Some studies have found driving skills impaired with a blood alcohol level of 0.02 percent — much lower than the 0.08 percent that’s the current legal limit across the U.S. At 0.05 percent, pretty much everyone’s unable to drive very well.