How Drunk Is Too Drunk to Drive?

Our podcast "The Suicide Paradox" featured sociologist David Phillips, who spoke about his research on copycat suicides (a phenomenon he calls "the Werther Effect"). More recently, Philips has been studying drunk driving. Particularly, he's been looking at drivers who are merely "buzzed" -- with 0.01 percent blood alcohol concentrations (BACs) -- and has found that the severity of life-threatening motor vehicle accidents increases significantly at BACs far lower than the current U.S. limit of 0.08 percent. In an email, Philips describes his latest research on buzzed drivers:

My current research, just published in Injury Prevention, shows that even minimally buzzed drivers (with BAC=0.01%) are 46% more likely to be blamed for an accident than are the sober drivers they collide with. This indicates that there is no safe level of alcohol for drivers: any amount of alcohol markedly increases the risk to drivers and their passengers. We reached this conclusion after examining an official, U.S. dataset of more than 570,000 car crashes. The findings have implications for drivers, passengers, police, judges, lawyers, insurance companies, advocacy organizations (like MADD) and regulatory agencies.

Is Driving Drunk Rational?

I doubt this statement will shock you or light up the blogosphere, but drunk driving is bad. Our own Levitt has looked at the costs, and found that those who have had even one drink are seven times more likely to cause a fatal crash, while for those over the legal BAC limit the risk is multiplied by 13. This equates to a cost to society of more than 40 cents per drunk mile driven (2013 dollars), implying that a fine of $10,500 would be appropriate if drunk drivers were to bear the full cost of their actions.

The good news is that we have made tremendous progress. According to the National Highway Traffic Safety Administration, road fatalities due to drunk driving have dropped from 21,113 in 1982 to 9,878 in 2011. The decrease is even more remarkable given that total miles driven almost doubled during that period. So the drunk driving fatality rate per billion miles traveled has dropped from 13.4 to 3.4 in the last 30 years.

Some of this is due to general improvements in driving safety, such airbags and increased seatbelt use. But this is only a part of the equation. A suite of policies specific to alcohol has also been implemented, with considerable success. These have been recently analyzed by Susan A. Ferguson and Koyin Chang, Chin-Chih Wu, and Yung-Hsiang Ying, among others. Successful policies have included toughening laws and their enforcement, such as reducing permissible blood alcohol content (BAC) levels, especially for underage drinkers. Sobriety checkpoints are a very effective enforcement mechanism, particularly if properly publicized. Other policies that have been found to be effective are higher alcohol taxes (very), and to a lesser extent laws banning open alcohol containers in cars and higher legal drinking ages.