Friday, August 26, 2022

Does Lowering BAC Limit To 0.05% Actually Save Lives?

We at Twenty-One Debunked have long supported lowering the legal BAC limit for DUI/DWI to 0.05%, with nuance and graduated penalties, based on what we thought was rock-solid research supporting such a move from the current 0.08% limit in most of the USA.  However, a pair of more recent British studies casts serious doubt on whether such a move will actually save any lives at all by itself.

The study, in the prestigious medical journal The Lancet of all places, looks at a sort of natural experiment where Scotland lowered their BAC limit from 0.08% to 0.05% in 2014, while England and Wales kept it at 0.08% throughout.  The results?  Scotland saw no significant absolute difference in weekly traffic crashes after the change compared with before, and even saw a statistically significant 7% increase in crashes relative to England and Wales.  Similar results were found when looking only at serious, fatal, or single-vehicle nighttime crashes, hence the results were robust as well.  And all of this was after adjustment for several possible confounders.  The study also found that, contrary to what some might predict, no overall change in per capita alcohol consumption in Scotland either, and only a 0.7% decrease in on-premise alcohol consumption.  Can you say, "Whoops!"?

(And no, the study was NOT funded by the alcohol industry or any of its front groups.  Sorry.)

Thus, it seems that while lowering the BAC limit from 0.15% to 0.10% and then to 0.08% long ago probably did save a significant number of lives (though the exact number is debatable), further lowering it from 0.08% to 0.05% has very diminishing returns at best.  And it can perhaps even backfire at worst. The Australian success story was far more likely due to very tough enforcement of DUI laws in general (including, but not limited to, their legendary random breath testing (RBT) program), while the Continental European success story was likely due to the same, plus world-class public transportation as well.

So why are the above results so lackluster then?  Well, as Darren Grant noted in his famous study debunking the effectiveness of zero tolerance BAC laws for people under 21, it should really come as no surprise to an economist, who is used to thinking on the margin.  While driving impairment indeed begins long before reaching 0.08% or even 0.05%, it rises exponentially with each drink.  Thus, higher BACs are exponentially more dangerous than lower ones.  And the decision to have one's next drink based on trying to stay within the legal limit, even if a lower limit had the same deterrent effect at that limit, would have exponentially less effect that the decision not to cross a higher threshold.  (If anything, it's even MORE exponential for younger drivers, not less.)  And apparently once when the limit goes down to 0.05% or lower, any additional lifesaving effect over and above lowering the limit to 0.08% simply gets lost in the statistical noise.  That is especially true if the penalty is the same for crossing a lower threshold, since there is literally no marginal deterrence effect against each additional drink beyond that threshold.

(Grant also did a sort of sequel to that study in 2016, again drawing similar conclusions.)

We already know that the vast, vast majority of DUI casualties are concentrated among extremely high BAC drivers, usually 0.15%+ (average 0.16%) and often ones who do so repeatedly and frequently.  These drunk drivers are sometimes called "hardcore" drunk drivers, and are the most resistant to changing their behavior.  And most of those are in fact alcoholics to one degree or another.  They would, of course, laugh at the idea of a BAC limit being lowered to 0.05%, or at the very least, wouldn't exactly agonize over it.  This is all common knowledge, and not at all controversial, except of course among MADD and similar zealots.

Thus, if we as a society decide to set the BAC limit at 0.05%, or indeed any number below 0.08%, there should be steeply graduated penalties, with 0.05% (or 0.02% for young or novice drivers) being a mere traffic violation with a modest fine and short-term license suspension, and no criminal record, 0.08-0.10% being a misdemeanor with a steeper fine and longer license suspension or revocation, 0.10-0.15% being misdemeanor with an even steeper fine and even longer license revocation and mandatory jail time, and 0.15%+ being a felony with permanent or semi-permanent license revocation, very steep fines, vehicle forfeiture, and a stiff prison sentence.  Repeat offenses of 0.08% or higher would carry the same penalties as a 0.15%+ BAC, as would driving above 0.08% with a child under 16 in the vehicle.

We also know that swiftness and certainty of punishment, or the perception of such, is a far greater deterrent than severity.  Thus, automatic administrative penalties, separate from any criminal penalties, are found to be more effective that any criminal laws on the books, most notably in the Canadian provinces of British Columbia and Alberta.

Of course, we would be remiss if we did not discuss the stunning success of special DUI/DWI courts.  These are diversion programs that allow DUI offenders to plead guilty and complete coerced treatment and enforced abstinence from alcohol instead of jail or other penalties.  And they work quite well, with far lower recidivism rates than for those who do not enter such programs.  There are two types of DUI offenders these days:  1) relative normies who simply make dumb decisions and can be "scared straight", and 2) hardcore drunk drivers.  And DUI courts actually get to the root of the problem for the latter.

But first, we need to get these ticking time bombs off of the roads before they kill or maim innocent people.  Australian-style RBT is one blunt way to do it, but that would not likely pass constitutional muster in the USA. And even then, the long-run effects of Australia's RBT were not very different than those of American-style sobriety checkpoints when studied in the 1980s.  Tougher and sustained enforcement in general really seems to be the key.  And that can of course be done more effectively and cost-effectively with roving and saturation patrols, that look for signs of actually impaired drivers on the roads.  Especially in the many states that do not allow sobriety checkpoints to take place, they HAVE to rely on DUI patrols instead.

(Twenty-One Debunked recently came up with an ingenious idea to turn roving and saturation police patrols against DUI into a COPS-like reality TV show called "Operation Rovin' Eyes", complete with ride-alongs for community members as well.)

Seasoned drunk drivers know how to avoid the checkpoints with ease.  But with roving and saturation patrols, they will soon learn (either the easy way, or the hard way) that you can run, but you can't hide.  "Roving eyes...are watching YOU!" would be a good slogan to publicize the program.  The "fish in a barrel" method, that is, parking a police car outside bars, clubs, or parties and catching would-be drunk drivers before they get on the road, would also be a great complement to such patrols as well.

And while we're at it, let's get all of the garden-variety reckless, negligent, and distracted drivers off the road as well.  The same patrols will of course get them too.

It's time to stop tilting at proverbial windmills, and finish the job for good.  So what are we waiting for?

P.S.  The drinking age in the UK is 18, in case you didn't already know.  Kinda like most of the world.

UPDATE:  What about weed?  Unlike with alcohol, Twenty-One Debunked does not support any per se limits for cannabis, only rational prima facie ones that are rebuttable, similar to what Colorado has.  The complex pharmacokinetics and lack of correlation between blood THC levels and actual impairment renders any per se legal threshold to be inherently unscientific, and there is still zero evidence that such per se laws save any lives or improve public safety at all.  While cannabis can indeed impair driving, and a fortiori when combined with alcohol, it is best to focus on those drivers that are actually impaired, rather than to snare perfectly sober drivers in the dragnet due to mere trace amounts of THC in one's system.

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