If you don't know when to say when, a cop will be happy to tell you. In most states, it's illegal to drive with a blood-alcohol concentration (BAC) of 0.10 percent or more, the level the average 170-pound man reaches after drinking a six-pack of beer in two hours.
The Clinton administration wants to take away one of those beers. It supports legislation, a version of which was approved last year by the Senate, that would withhold highway money from states that do not adopt a BAC cutoff of 0.08 percent, which is the standard in 16 states. "If all states lower their BAC to .08," President Clinton has said, "it will result in 600 fewer alcohol-related deaths each year."
But according to a recent report from the General Accounting Office, it's not clear that making this switch would save any lives, let alone 600. "Overall," the GAO says, "the evidence does not conclusively establish that .08 BAC laws, by themselves, result in reductions in the number and severity of alcohol-related crashes." The report calls the figure cited by Clinton "unfounded" and emphasizes that, as the authors of one study put it, "it is important to interpret estimates of lives saved due to any single law with considerable caution."
The major difficulty in trying to assess the impact of a 0.08 BAC standard is the need to control for other factors, such as increased enforcement, public awareness campaigns, and license revocation laws, that tend to coincide with the shift to a lower limit. The GAO notes various other methodological weaknesses in the seven studies that have been conducted so far, including the choice of comparison states and the indexes used to measure alcohol-related accidents.
The report, available at www.gao.gov/new.items/rc99179.pdf, concludes that the National Highway Traffic Safety Administration has exaggerated the strength of the evidence. In December 1997, when only four studies had been published, the agency declared that "recent research...has been quite conclusive in showing the impaired driving reductions already attributable to .08." Three studies later, according to the GAO, we still have not reached that point.