No, the world is not cleanly divided between designated drinkers and designated drivers. There is some serious overlap; the kind that puts many people at risk. In fact, a University of Florida study found that 35 percent of designated drivers had quaffed alcohol and most had blood-alcohol levels high enough to impair their driving. A University of Florida news release reports that when researchers interviewed and breath-tested more than 1,000 bar patrons in the downtown restaurant and bar district of a major university town in the Southeast, they found that half of the designated drivers recorded a blood-alcohol level higher than .05 percent — a recently recommended new threshold for drunken driving. The non-driving participants had significantly higher levels than the designated drivers, but 35 percent of the 165 self-identified designated drivers had been drinking. Seventeen percent of all those drivers tested had blood-alcohol levels between .02 and .049 percent, while 18 percent were at .05 percent or higher. Read more from the University of Florida.