John Hult offers a good thorough discussion of the ins and outs of the National Transportation Safety Board's recommendation that states lower the blood-alcohol threshold for DUI charges to 0.05%. The policy and enforcement folks Hult talks to don't sound enthusiastic. But Judge Larry Long tells Hult that back in the 1970s, he had trouble getting juries to convict drunk drivers for exceeding the then-BAC limit of 0.15.

I like this summary of the question from Hult:

We all know people who think they’re okay after a few drinks. We all know people who have a higher tolerance and seem unaffected after drinking enough to lay another person out. Some of us have heard stories about Uncle Joe So-And-So who drank 12 beers a night at Yakadee Smack’s Downtown Pub for 20 years and drove home all the time but never hurt anyone.

Setting the bar at a certain level is society’s way of saying it doesn’t matter how lucky Mr. So-And-So has been. Once a person gets X amount of alcohol in their system, the science says it’s too risky for that person to get behind the wheel.

Let’s put it this way: It’s conceivable that there are people out there who, under the right circumstances, could drive away from a place at midnight with no headlights on and still make it home without a wreck. That doesn’t mean the person gets a pass on a law that says you need to drive with your headlights on after hours.

So that’s what the debate is about on a broader level, but changes to the legal limit have serious, real-world consequences in court [John Hult, "Is a .05 blood alcohol limit a possibility in South Dakota?" Amicus Lector, 2013.05.17].

As a teetotaler, I'm not the guy you want making the rules. I would suggest that if you're driving, you're not drinking. Period. There is no compelling reason to have any alcohol in your system when you're operating the deadliest household equipment in the country. When alcohol is the third-leading cause of preventable death in the U.S. and traffic collisions are seventh, we're justified in drawing a pretty strict line between alcohol and driving.