Are Low BAC Drivers a Problem for Traffic Safety?

Are low BAC drivers causing a high proportion of traffic crashes? Setting the maximum legal blood alcohol concentration is a matter of public policy debate. It’s often heated. Research can replace much speculation and emotion with facts.

It’s often suggested that the maximum legal BAC be reduced by 38%. That is, down to 0.05. This is opposed by both the hospitality industry and a large proportion of drivers and others. This includes many safety experts. How serious are the problems caused by low BAC drivers?

The Study

Research was designed to answer that question. It used quasi-experimental propensity score matching techniques. This was in combination with multilevel modeling. The researchers reported significant findings


Low BAC drivers are involved in a very small proportion of crashes. They are not at fault in many of these. In those cases, their BAC is irrelevant to the crash.

low BAC driversLow BAC drivers are at a slightly higher risk of crash-involvement than those with no BAC. So such drivers are a problem. However, this increased risk from low BAC is much lower than that of any one of a number of other factors. These include age, distraction, speed, high BAC, and drug use.

Public Policy

It is never wise to drive with any BAC. But this research strongly suggests that changing public policy priorities might be wise. More effective use of time, money, and other resources could save more lives.

That’s a goal on which everyone should be able to agree.


Stringer, R.J. Are buzzed drivers really the problem: a quasi-experimental multilevel assessment of the involvement of drivers with low blood alcohol levels in fatal crashes. Criminal Justice Policy Review 0887403416637187, first published on March 17, 2016 as doi:

Resources on Lowering the Legal BAC.

Alexander, J. BAC: How low should it go? The 0.05 BAC debate. The Post-Star.

Chapman, S. Why Government Shouldn’t Lower the BAC Bar for Drunk Driving.  It’s a utopian goal requiring excessive compulsion in the pursuit of unattainable perfection.

MADD Founder: Don’t Lower the Legal BAC Limit. Candace Lightner says criminalizing .05 BAC level would be ‘a waste of time.’ U.S. News & World Report. Newsgram.

USA Today Editorial. Don’t lower blood alcohol content to .05%: Our view. USA Today.