A sober approach to drunk driving

The downside of a tighter DUI standard

May 23, 2013|Steve Chapman


The NTSB is dissatisfied with the rate of progress against drunken driving deaths. It makes much of the fact that the percentage of traffic deaths involving intoxicated motorists has been stuck at between 30 and 32 since 1995. But that figure masks improvement.

Between 1982 and 1994, the total number of people killed in crashes involving a driver who was impaired dropped by 37 percent. In the time since, the figure has declined by 26 percent. Things are getting better — just not as quickly as before.

The earlier progress came after states lowered the blood alcohol content for driving under the influence from 0.10 to 0.08, raised the drinking age and adopted a "zero tolerance" rule for drivers under age 21. With the most potent changes already in place, public safety improvements have gotten a bit harder to come by.

One study found that lowering the BAC standard has saved some 360 lives a year. So the agency concludes that we should lower it all the way to 0.05, which it figures would save 500 to 800 lives per year.

From the standpoint of individual behavior, that would be a significant change. A 180-pound man could be legally impaired if he had three drinks in an hour (versus four drinks today), while a 140-pound woman could earn a set of handcuffs with just two drinks in an hour (compared with three under the current rule).

The NTSB says 0.05 makes sense because driving performance is affected even before a motorist reaches 0.08. That's undoubtedly true. But all sorts of factors affect driving performance, from medications and lost sleep to missed meals and electronic distractions. Not every possible impairment warrants criminal punishment.

As it happens, drivers whose BAC is higher than 0.01 but lower than 0.08 account for only 5 percent of all highway deaths. The agency estimates that a motorist with 0.05 BAC is 38 percent more likely to crash than one who is stone-cold sober. That sounds like a lot until you realize that someone with a 0.08 BAC is nearly three times more likely to be involved in a wreck than an abstainer. At 0.10, the risk is nearly five times greater.


Under a tighter BAC, the same number of cops will be chasing a lot more offenders. An officer who is busy arresting someone with a 0.05 level, who poses a small danger, will not be able to arrest someone with a 0.10 or 0.15 level, who poses a huge danger.

Forgotten in these number-crunching exercises is the effect on the trivial matter of human spontaneity and enjoyment. NTSB may place a zero value on the pleasures of social drinking, but social drinkers don't. In any cost-benefit analysis, the loss of a largely harmless pleasure deserves inclusion.

Not only that, but the cost of a stricter policy is greater than it may appear. When you lower the limit, you deter not only forbidden levels of consumption but permissible levels. Why? Because most people don't care to be anywhere close to the line.

They don't travel with Breathalyzers and want to be absolutely sure of not being arrested for DUI — which carries not only legal penalties but social disgrace. If this were a constitutional right, we'd be talking about a "chilling effect."


The NTSB acknowledges that last policy would save some 1,100 lives per year — far more than a lower BAC would save. It also has the virtue of disabling the few guilty without inconveniencing the many innocent.

In a free society, reaching zero carries too high a cost. Better to settle for making progress.



Twitter @SteveChapman13