December 24, 2006
Drunk Driving
Fatalities from Drunken Driving--BECKER
One of the most disturbing aspects of the holiday season is the sharp rise in automobile fatalities, in part due to drunk driving from overdrinking at parties and other celebrations. The United States has almost 40,000 deaths per year from automobile accidents, and about 40 percent are due to drunk driving. This exceeds the annual number of deaths from major diseases like prostate and breast cancers, and drunk driving deaths are also concentrated among young persons, while deaths from most diseases come at much later ages.
That the number of deaths per mile driven is not fixed but varies greatly with different conditions is seen from the wide differences among countries in the number of deaths per passenger vehicle. The United States is at the high end, and in 2004 had about 1.8 road traffic deaths per 10,000 vehicles, compared to less than 1 per 10,000 vehicles in Sweden and Norway, 1.1 in Germany, and 1.0 in the United Kingdom. A few countries in the more economically advanced nations have higher death rates than the United States, including S. Korea at 3.6, and Hungary at 3.9. A number of factors help explain these international differences, including the quality of the roads, speed limits, minimum driving ages, age distribution of the driving population, density of traffic, amount driven per vehicle (presumably higher in America), and other factors. I concentrate on accidents due to drinking.
The American approach to drunk drivers has been more laissez faire than other nations, with relatively light punishment for drunk driving, often even when it caused serious accidents. In the last couple of decades, however, under pressure from groups like Mothers Against Drunk Driving (MADD), states and the federal government have begun to crack down on drunk driving, and driving by youth. Largely in response to such pressure, the minimum drinking age in all states has been raised from what was typically age 18 to age 21. States also established more standardized criteria for what constitutes driving while drunk, and have lowered the minimum level of blood-alcohol concentration that is taken to indicate driving while drunk from 0.10 per cent to 0.08 per cent. More checkpoints and patrols have been put on the road to give sobriety tests to suspected drunk drivers.
As a result, alcohol-related fatalities fell dramatically from 1982 to 1994. But the trend has stalled since that year, and alcohol-related driving fatalities have bottomed out at about 17,000 per year. When adult drivers cause their own accidents or that of their passengers because they were drunk, one can reasonably assume they and their passengers are capable before they get drunk of determining what risks to take, such as whether to drive, speed, how much alcohol to absorb, and other factors that increase their risk of an accident. But drunk drivers often kill or injure persons in other cars, or pedestrians, and in this way they impose what are called negative externalities on these innocent victims. This is the main case for public policies to reduce drunk driving and other externality-causing driving behavior.
One approach is to tax gasoline and perhaps cars to cut down the amount of driving. Another way is to tax alcohol to cut down the amount of alcohol consumed. But these are very blunt policy instruments because they punish also people who drive without driving while drunk, or people who drink even in large quantities without driving or otherwise endangering others. By punishing only people who are discovered to be driving while drunk, or who get into accidents because they were drunk, or who are much more likely than others to drive while drunk, such as teenagers, one avoids much punishment of drinkers or drivers who do not risk the lives and property of others, and concentrates punishments on those who either are likely to, or actually did, impose external costs on others. At the same time, this would discourage, perhaps greatly, the tendency to drive after heavy drinking.
My colleague, Kevin M. Murphy, prepared estimates for the United States for the year 2000 of the total cost imposed by drunk drivers who get into accidents on drivers and passengers in other cars, and on innocent pedestrians. These costs include estimates of the statistical value of the lives lost (see my post on September 3, 2006 for a discussion of this concept), the value of medical expenses for those injured, and the value of the property lost. The total of all these external costs from drunk driving in the year 2000 is about $15 billion, with the great majority of this total coming from the $5 million value placed on each of the more than 2,000 innocent persons who lost their lives in that year because of drunk driving.
About 1.4 million persons in that year were arrested for drunk driving. Given the calculations in the previous paragraph, this means the cost imposed on others from driving while drunk amounts to about $10,000 per person arrested for drunk driving. This is a large amount, and provides a first order guidance to the punishment that should be imposed in some form on the drunk drivers arrested: large fines, suspended licenses, and jail terms in some cases. Such large punishments would match the damages done from drunk driving, and at the same time would encourage many persons to avoid driving while legally drunk. To show this with a little algebra, suppose that g per cent of all drunk drivers (=N) are arrested, and let that be the same for everyone- presumably it is higher for those who actually cause accidents. Let the punishment to those arrested be d per person, which is Murph''s $10,000 figure, where d=D/gN, and D is total damages from all accidents caused by drunk driving. Then the total punishment to those arrested =gNd=D, which is the right number in order to have drunk drivers pay for all the damages to others that they cause.
On incentives to drunk drivers, the expected damages per drunk driver =gd=gD/gN=D/N= damages per drunk driver=p D/pN, which is what it should be, where p is the assumed common probability that a drunk driver gets into an accident. The assumption of a probability common to all drunk drivers of causing an accident is clearly not perfectly accurate, but far better than the assumption that all persons who drink are equally likely to harm others. Morover, the size of the punishment might not be the same for all those arrested, but could depend on alcohol-blood levels, the recklessness of the driving behavior, and the severity of the accident if they had been in an accident, past offenses, and other factors that try to relate punishment to the magnitude of the "crime" committed and the degree of individual responsibility.
To my knowledge, no state in the United States imposes anything approaching such serious punishments on persons arrested for drunk driving. In fact, they are generally much too lenient, and do not treat this as the serious crime that it is. Countries like Sweden are much harsher in their punishment of persons arrested for drunk driving. Driving with a blood alcohol level exceeding only 0.2 parts per thousand may lead to prison terms of up to six months, and the driver's license is usually suspended. Driving with a blood alcohol level of over 1.5 may lead to one year of prison. My experience there and in Norway is that these deterrents work very well, and induce people who are planning on drinking any significant quantities to be careful not to drive afterwards. Several econometric articles by H.L. Votey indicate that punishments by fine, revoking of driving licenses, and imprisonment are important in explaining the lower tendency in Sweden to drive while drunk and the lower rates of accidents due to drunk driving, although some of the results are disputed by H. Lawrence Ross.
The American approach to drunk driving is surprisingly soft, often including the treatment of drunk drivers who seriously injure or kill innocent persons because of reckless driving. Given the sharp increase during the past 20 years in the severity of punishments for felonies, and the over 2 million persons in jails or prisons, this reluctance to try to cut down the disgraceful number of highway deaths due to driving while drunk is anomalous and disturbing.
Drunk Driving--Posner's Comment
This topic could be thought a continuation of our last week's topic, the trans fat ban in New York City. We are again dealing with safety regulation. The case for punishing drunk drivers may seem clearer than the case for banning trans fats in restaurant meals because the externality is more pronounced and consumer competence is not in issue, but the appearance is deceptive. Becker's proposal for heavier penalties for drunk driving could be criticized as paternalistic, because it regulates an input rather than an output. If there are 1.4 million annual arrests for drunk driving, and if we assume realistically that this is only a fraction of the actual incidents of drunk driving, yet only 2,000 innocent people are killed by drunk drivers, then it follows that most drunk driving is harmless. Why then punish it with arrests and severe penalties? Why not just punish those drunk drivers who cause deaths or injuries to nonpassengers? In fact we do punish such drivers, under such rubrics as reckless homicide (if the victim dies) or reckless infliction of bodily injury. And the punishments are severe. Why punish the 99+ percent of drunk driving that is harmless? Indeed, if the penalties for reckless homicide are optimal, the implication is that the number of deaths from drunk driving, 17,000 a year, is also optimal.
This is actually a plausible inference. If there are only 2,000 nonpassenger deaths (other than that of the drunk driver himself) caused by drunk driving every year (and how many of the accidents in which a drunk driver is involved are actually caused by the drinking?), then the probability of being killed by a drunk driver is very small, and the value of life estimate that I used in my post on the trans-fat ban should be usable here as well to conduct a cost-benefit analysis of drunk driving. The probability of a drunk driver's killing someone must also be small, given the number of drunk drivers implied by the arrest statistics. Suppose the annual probability that a drunk driver will kill a nonpassenger is.001 (as it would be, given the 2,000 victim figure, if there are 2 million drunk drivers, which is a very modest extrapolation from the arrest figure, since many drunk drivers are not caught). Then the expected injury cost from drunk driving is $7,000 (.001 x $7 million). (This corresponds to Becker's $10,000 figure, which seems to me too high, as it disregards the drunk drivers who are not arrested. Notice that if only a third of drunk drivers are arrested each year, the expected-cost figure drops to $3,333.) This implies that a driver who derives at least $7,000 in utility per year from drinking while driving (more commonly, shortly before driving) is behaving optimally and should not be punished at all.
The larger issue that the drunk-driving question raises is the choice between ex ante and ex post regulation. Health inspections of restaurants and, yes, a ban on trans fats are examples of ex ante regulation. Such regulation prevents dangerous activity rather than waiting for the danger to materialize and using the legal system to punish the injurer. The tort system is an example of ex post regulation. If you drive recklessly but don't injure anybody, you have not committed a tort. Tort law comes into play only when an injury occurs. The theory is that an optimal tort penalty for the injury deters tortious conduct, not perfectly--or there would be no tort cases--but well enough.
Criminal law is a mixed bag. Crimes that result in injury are punished, usually quite severely, but much preparatory conduct--attempts and conspiracies--is punished as well, even when no harm results (the failed attempt, the abandoned conspiracy). Arrests for speeding--and for drunk driving--are examples of ex ante regulation. The economic argument ex ante regulation is that ex post regulation is often inadequate. This is obvious in the trans-fat situation--it would be impossible to figure out which victims of heart disease owed the disease, and to what extent, to which restaurants. In the case of reckless homicide, the answer is less clear. Suppose drunk driving is inefficient--the drunk driver derives less utility than the expected accident cost--and so we want to deter it by punishing the drunk driver who kills or injures a nonpassenger. Suppose the value of life is $7 million and 10 percent of the drivers are not apprehended. Then the optimal penalty would be a fine of $7,780,000 ($7 million √∑.9). Few drivers could pay that, so the trick would be to impose an equivalent disutility on them by nonpecuniary means, such as imprisonment.
This is not to suggest that punishing drunk drivers who are arrested, the method that Becker endorses, can't achieve the correct deterrence. But punishing just the ones who kill might be more efficient--there wouldn't be as much need for policemen, there would be fewer trials and prison terms, and probably many drunk drivers are quite harmless, for it is unlikely that everyone who drives while drunk has an equal probability of causing an accident. In general, heavy punishment of fewer people is chaper than light punishment of more people.
Thus, only if ex post punishment failed to deter optimally would there be a strong case for punishing drunk drivers who are not involved in accidents with nonpassengers (assuming drunk driving is inefficient, the assumption questioned earlier in this comment)--or at least a strong case based on the simple model of rational choice that underlies my analysis. Maybe drunk drivers systematically underestimate the effect of drinking on the likelihood of an accident, or believe that they can fully compensate for the danger by driving more slowly, or exaggerate the degree to which they can hold their liquor, or exaggerate their driving skill. Maybe their drunk-driving behavior is addictive, and they do not realize, before starting to drink, that they won't be able to avoid drinking before they drive. These might be grounds for ex ante regulation--even for regulations anterior to arrest, such as stiff alcohol taxes.