WASHINGTON — Getting liquored-up and getting behind the wheel hasn’t been cool for 20 years at least — and the general public opprobrium has had demonstrably positive effects. According to the National Highway Traffic Safety Administration (NHTSA), the number of “alcohol-related” traffic deaths has dropped by more than 50 percent since the early 1980s — 0.63 per 100 million vehicle miles traveled (VMT) in 2001 vs. 1.64 per 100 million vehicle miles traveled in 1982.

The question is, are tighter penalties for drunk driving — and more vigorous enforcement — deserving of the credit for this reduction in carnage? Or is it more a consequence of mass enlightenment that drinking to excess and driving don’t mix? Groups such as Mothers Against Drunk Driving (MADD), which actively pushed for ever-more-strict laws and penalties in state legislatures around the country, argue the former.

It’s probably a mix of both.

At some point a general epiphany seemed to occur to most people that made them think twice about getting behind the wheel after more than a couple drinks. The flip side, of course, is the prospect of rolling up on a “sobriety checkpoint,” flunking the Breathalyzer test — and getting a night’s pass to accommodations in the county clink.

It’s interesting how we’ve swung from one extreme to the other in the space of just two decades. Before the early 1980s, having “one for the road” was a common closing time thing to do. Remember movies like Cannonball Run with Dean Martin driving a Ferrari with one hand on the wheel and the other clutching a Chivas over ice? That was considered funny in those days.

Imagine the reaction today.

That brings us to the issue of political correctness as applied to the drunk-driving issue. It’s one thing to object to the idiots who put their own and others’ lives at risk by operating a motor vehicle when they’re impaired by alcohol. Clearly, those people should feel the weight of the state descend upon them. But we’re now at the point of “defining drunkenness down” by lowering legal standards for impairment to the point of absurdity — and of employing random tactics such as “sobriety checkpoints” that subject people who have done nothing to even warrant suspicion to a once-over by armed agents of the state.

MADD has gone on the record arguing in favor of establishing an almost zero-tolerance policy for any trace of alcohol in a person’s bloodstream — writing it into law that Blood Alcohol Content (BAC) levels of .06 or even .04 be sufficient to incur a charge of driving under the influence.

Most states have set the maximum allowable BAC level at .08 — the point after which it can be proved scientifically that most people suffer some degree of impairment in the form of diminished reaction times and so on. However, there is no evidence that minimal BAC levels of .06 or less — which can be reached after a normal-sized person has had a single drink with dinner — correlate with a greater likelihood of having an accident as a result of diminished capacity.

It’s one thing to lock up the person who is weaving all over the road — quite another to arrest a person at a sobriety checkpoint simply because he has trace amounts of alcohol in his blood.

Mothers Against Drunk Driving — a fervent backer of sobriety checkpoints — deploys heavy-handed rhetoric to shout down any who don’t share the group’s almost manic enthusiasm for the crusade: “Opponents of sobriety checkpoints tend to be those who drink and drive frequently and who are concerned about being caught,” according to MADD — although no evidence is given to support this slander. (Italics added.)

However, one can legitimately object to the use of random stops by police absent probable cause without also endorsing or excusing “drunk driving” — just as one doesn’t have to be a “tax cheat” to object to random IRS audits — or “support criminals” because one believes that police should be required to secure a warrant before conducting a wiretap or search of anyone’s home.

Getting “drunks off the road” is entirely beside the point.

The question is whether it’s in keeping with a free society to treat everyone as a criminal a priori — and whether it’s proper to adopt an “ends justify the means” philosophy that is the reverse of the principles enshrined in our founding documents. There is arguably no principle more fundamental to the life of a free society than that a person should not have to deal with the law until and unless he has done something to transgress it — or given cause for reasonable suspicion that he may have.

The anti-drunk-driving groups have done a great service in helping to enlighten the general public — and making it socially unacceptable to drive while drunk. But knowing when to say “when” applies just as equally to social and legal policy. Just because we went on a bender in the past doesn’t mean neo-prohibitionism is the answer today.

Reasonable people favor reasonable laws.