Should We BAC Down?

Drunk driving doesn’t grab our attention like the oil slick, perhaps because the damage comes in a steady drip instead of (literally) one big gusher. But the costs we pay for the interaction between alcohol and driving are large, in terms of lives lost, medical care, property damage, enforcement, and more.

There are definitely ways we could save lives through additional policies to control DUI. But some may be more effective than others, and all would come at a cost in terms of a pleasure that many of us enjoy and even rely on. So which trade-offs might be worth making?

Here’s one possibility: cutting the legally permissible BAC from .08 to .05. James C. Fell and Robert B. Voas have done an extremely helpful study that reviews the research on this potential policy change.

The beauty of studying BAC limits is that we have lots of neat natural experiments; over the years many places have lowered permissible alcohol levels, so we can see what has happened when they did.

For example, at the start of the 1970s some states had no formal legal BAC limit, and most that did set it at .15. Eventually, most states moved to .10. Starting in 1983, states began to reduce this to .08 and since 2002 all states have been at that level.

This change has been accompanied by a precipitous drop in accidents involving alcohol: in 1982 there were 1.64 alcohol-related road fatalities per 100 million miles driven, and in 2008 there were only 0.40.

Granted, we can’t attribute all or even most of this to reduced BAC limits. Lots of different anti-drunk driving measures were taken during that time, like better education and harsher penalties. Besides, travel in general got safer thanks to better cars and roads.

Scholars do, however, try to take these things into account and can tease out what the BAC limits do, independent of other factors.

What happened when states went down to .08? Approximately 20 scholarly analyses have found strong evidence lives were saved. The median study found that, thanks to the .08 limit, fatal crashes involving alcohol dropped by about 7 percent.

For reference, we had about 12,000 fatalities from crashes involving alcohol in 2008, so this very roughly implies an annual savings of well over 800 lives.

Other studies have reached very similar findings. D. Eisenberg found that the more strict limit cut total traffic fatalities by 2.6 percent, implying at least 1000 lives saved annually, and A.S. Tippetts, R.B. Voas, J.C. Fell and J.L. Nichols found that if all states had the .08 limit in 2000 over 900 lives would have been saved that year.

Since the drop to .08 was effective, what if we took the next step, to.05?

At least 100 studies show that driving with a BAC below our current limit of .08 — but above above .05 — is quite dangerous (see this review from H. Moskowitz and D. Fiorentino). For example, P.L. Zador, S.A. Krawchuk and R.B. Voas found that drivers with a BAC between .05 and .07 have 4 to 10 times the risk of being in a fatal crash compared to sober drivers.

Cutting the limit to .05 would be far from unprecedented. At least 52 nations have done it, including Brazil, China, India, Russia, the Nordic countries, Argentina, France, Germany, Italy, Greece, Spain, Taiwan, Thailand and Turkey. And none of their civilizations are collapsing, with the possible exception of Greece’s, and that for unrelated reasons.

Several studies have found that countries experienced positive results when they went down to .05. For example, J. Henstridge, R. Homel and P. Mackay reported that fatal crashes dropped 18 percent in Queensland, Australia and eight percent New South Wales (even controlling for other anti-DUI measures).

What would the effects be in this country? To the best of my knowledge no projections exist. But in 1998, a very thorough study by R.E. Mann, S. Macdonald, G. Stoduto, S. Bondy and A. Shaikh looked at what the effects of a national 0.05 limit would be for Canada, a country with driving and DUI levels in the same ballpark as ours.

They concluded that the adoption of a .05 BAC limit would cut motor-vehicle crash fatalities by 6 to 18 percent. To make an admittedly very back-of-the-envelope calculation, taking their most conservative estimate and applying it to the current US fatality rate indicates that perhaps 2,400 lives would be saved by this policy.

But at what cost? Well, we’d have to drink less. Determining how many drinks result in a particular BAC is extremely hazardous, since much of it has to do with factors like weight and metabolism. But to be on the safe side, drivers, particularly lighter ones, would have to limit themselves to a single drink before climbing behind the wheel.

Are hundreds or quite possibly thousands of lives a year worth this sacrifice? One could certainly make the case that the answer is “no,” given that there are millions of us who enjoy alcohol very much. Certainly there are plenty of other policy arenas where we trade off death for pleasure (smoking, motorcycle riding, junk food consumption), although most of those don’t jeopardize others the way drunk driving does. In any event, I’ll leave it up to you to decide if you’d be willing to turn that second beer into a root beer.


...your crusade, not the legal BAC limit.


I'd perfer a differnt solution:

If you have a BAC over .05 and happen to injure someone, it is treated as a premeditated murder/attempted murder.

Otherwise the .08 remains the same. People who pass sobriety tests at .15 shouldn't have to live by the same rules as people who fail at .03.

Tom G

While I would support this, if we are going to make the trade-off of using resources fighting for better drunk driving laws, increasing the certainty a drunk driver (using the current bac definition) is caught is by far the best way to go


At some point, the limit reaches an 'unconstitutional' level. I wonder if it would be possible to go lower than .08 legally. Not an expert myself, just a thought.


How about we have a drunk driving section on our licenses. You go in for a special test to see at what BAC your driving skills fall below some pre-determined standard of quality. You are allowed to drive at that BAC. If you haven't had the test (a test you should also be forced to pay for) your acceptable BAC is 0.

Mark Brucker

I think another way to address this problem and many others would be mileage-based insurance. Currently people who drive few miles subsidize those who drive a lot. Mileage-based insurance would mean that those who are most dangerous pay the most per mile to drive. Which would give them a very strong incentive to cut down on mileage and to try to reduce their risk rating. So it ought to cut down most on mileage by those who create the greatest danger. While also cutting down in driving in general and therefore crashes, pollution, deaths, injuries, etc. And therefore cutting insurance costs a lot-about $300 per driver in one forecast. A couple of studies estimate the potential savings in California alone at over $20 BILLION a year when taking into account total savings.


How about different offenses for different vehicles?

The cost imposed on the rest of society is much lower if I hit another vehicle with my 500lb motorcycle, than a fullsize car or a truck.

I'd bet there's an order of magnitude greater externality associated with a drunk cager collision vs. a drunk biker collision.

(Yes, I am aware that my own costs in that collision may well have been ultimate--but I got no problem suffering for my own stupid)

Timothy Brownawell

And yet it's still legal for me to stay at work until 3am and then drive home while changing the radio station every time a commercial comes on.



I'm all for adhering to the constitution and retaining our rights, but I'm not aware of the section wherein driving is considered a right, much less impaired driving. If driving were a right we wouldn't have to get a license to do it.

@Norm and @Alex

Both interesting, and good ideas.

One other idea, coming from someone who doesn't drink at all due to personal and religious reasons, is to progressively punish drunk drivers who injure others based on whether the victim was a drunk driver themselves. For example, if Tom is drunk and kills Jim and Bob he gets two different punishments; one moderate punishment for Jim because Jim himself drove occasionally while intoxicated, thus putting others at risk himself. On the other hand, Bob's death would result in a greater penalty because Bob never drove when intoxicated and thus had never himself put others at unnecessary risk.

Of course this would be far too complicated to put in place and impossible to track, but to a non-drinker it seems only fair.



I think the thought experiment should take the BAC to 0.0. If you have a drink, you can't drive. Clearly deaths due to alcohol would not go down to zero, in fact, I bet we'd still see something close to 10,000 deaths a year due to alcohol.

Reducing the BAC in light of that possible result would seem to point out that we're not solving the problem of many drivers who will drink and drive regardless of the law. We need to come up with an approach that reduces that figure, like a BAC sensor built into the steering wheel.


Having never been able to play around with a breathalyzer, I am pretty unsure what .08 BAC feels like. Also, when I am out with friends, we drink from pitchers of beer or mixed drinks that the bartender prepares - I don't know how many "drinks" I am having.

I have no idea when I become too drunk to legally drive. And rather than try to do all the math necessary, I have long since just started walking (Australian issues aside) or using public transportation on nights when I plan to drink.


To the best of my knowledge, driving with any alcohol in your blood is not a constitutional right.

No one is saying don't drink. It is not about drinking or enjoying alcohol. It is about one person's behavior posing such a huge risk (death) to so many others. Drink til your in a coma for all I care, just do not threaten the lives of othres with a 2000+ pound metal weapon when you do.


I would fully support lowering it to .05.

Post #2, treat anything over .05 as premeditated/attempted murder, is fair, isn't it?


My problem with this, since they have recently changed the BAC limit here in Ontario, Canada from .08 to .05, is that I have no idea when I'm over that limit.

Over the years I developed a sense of what I think .08 is (never knew for sure) and now they want me to stay below .05?! How is it possible for someone to know whether they are over the limit or not until one gets pulled over?

There needs to be a way for people to self verify their BAC for this to really work. I find it super annoying that the government has changed this value that is practically unknowable. For me, my BAC is an arbitrary value. I've never been pulled over and tested, so how can I even have a frame of reference for what .05 feels like? Or how many drinks over what period time is safe?

PS I'm not looking for the "the only way to be sure is to have zero drinks" answer.


Does the Pareto Principle play a role here? It would seem (if I understand it correctly) that 80% of the DUI problem is caused by 20% of the drunk drivers.

That would mean, would it not, that some drivers are repeat offenders.


You don't get multiple times to endanger innocent lives and be a threat to society. If you do it once, you ought to be jailed for years. But to be caught twice.... Well, as far as I'm concerned, any judge that lets off a DUI offender who has been convicted before (or for that matter, was let off on a technicality) should be shot or, barring that, made to leave office. The judge has become aided and abetted a criminal who endangers the innocent.

Very simply, once is bad enough. But to be given MULTIPLE changes...well, shame on us!

Al V.

I read a recent article that stated that in Norway, the punishment for driving with ANY alcohol (defined as .02 BAC) in your system is 1 year hard labor, and everyone in the car loses their license for a year.

What's the objective here? Is it to eliminate drunk driving completely? Reduce the allowable BAC and increase the punishment will reduce the incidence, but how far do we want to go? At the extreme, public execution of anyone over .02 BAC would provide the maximum deterrent, but is deterrence the only objective?

There's also a social cost of taking people away from their families and jobs if we overdo it, as we've seen in this country with our over-zealous drug laws.


Let's let the market economy rule the BAC too!

Let's deregulate the whole thing:

1)Lift all BAC restrictions for driving.

2)In the occurrence of accidents, analyze BAC, sleep drowsiness, drug use, etc. Make those statistics public.

3) Finally, give the insurance businesses discretionary power to investigate our drinking habits etc, and to establish premiums based and impose fines and penalties on undesired behaviors.

That will give individuals big incentives to stay sober, or drink responsibly.

An insurance company could, for instance, foreclosure your home if you drink, or drive half-asleep. To close the gap, give the police the authority to check your insurance when they stop you, and collect information on behalf of insurers.

Tell me, haven't similar deregulated approaches supported by our authorities worked like a charm in other industries?


how about we fulfill the liberal fantasy of full intrusion on our lives, lower the limit to .00 and put ignition interlocks (BAC testers) on every car. we might as well ban parking lots at bars because nobody can drive home legally after even 1 drink. the govt can then subsidize the construction of hotels in these former parking lots as people will be spending a lot more time sleeping it off before they go home. these hotels will also employ some of the restaurant/bar employees who would be out of work due to reduced alcohol consumption.

in all fairness, eating, listening to the radio and talking on the cell phone while driving will be treated like DUI, since those distractions have a similar effect on driving ability.


"there are plenty of other policy arenas where we trade off death for pleasure ... although most of those don't jeopardize others the way drunk driving does."

driving jeopardizes more lives than drunk driving, so why not just make it harder for people to obtain their licenses? if you have to work harder (and/or pay more) to get it, you'll [i assume] be more conscientious about losing your license.

people are going to continue to drink, and some will drive drunk. but if we have smarter drivers i think the drunk driving problem (along with other driving problems) will be mitigated.


If we really want to cut down on drunk driving, why don't we start by mandating that bars/taverns have on site breathalyzers? Look at the comments above, no one quite knows what the difference is between .08 and .05, does changing the limit really matter when its still up to impaired people to ask themselves "have I had too much," and make some coinflip guess?