Whatever its success in economics, the supply-side approach to drug abuse is a bust. Seal the borders. Arrest traffickers. Buy out, burn out or otherwise persuade Turks to grow peanuts instead of poppy.

For politicians this is the preferred approach, but unfortunately it does not work. After enormous expense and effort and much corruption, about 90 percent of foreign drug shipments get through to the United States. The 10 percent loss puts a crimp, but not much more, in the smuggling business. At most, it may raise prices.

What to do? As long as the United States remains a black hole for drugs, supply will persist. If we are ever going to get a handle on the drug problem, it is going to have to be from the demand side. How? How to stop not just pushers but users? Three ways.

The traditional approach uses the law. Throw the book at users. Punish possession with the courts -- and jail.

In principle, the Prohibition-style approach works, but you need two things: big jails and a strong stomach. Big jails, because there are so many drug users. Twenty million use marijuana regularly, five to six million use cocaine.

And a strong stomach to impose appallingly disproportionate sanctions for mere possession. A little over a decade ago, there were nearly 800 people in Texas jails with an average sentence of about 10 years for marijuana possession. Seems like a long time. Today our jails are too small and our stomachs too delicate for such meascordingly, the use of the law to punish and deter drug use has been in steady decline.

Hence the modern approach, the soft sell: "public education." It can work. It did, with remarkable swiftness, with regard to tobacco. In 1965, 43 percent of the population smoked. Twenty years of relentless deglamorization later, only 32 percent smoke.

The cultural change with tobacco, however, was not just a triumph of public relations. It came about through considerable coercion -- namely, the banning of cigarette advertising from television and radio. Take away the most glamorous portrayal on the most glamorous medium, and then antismoking propaganda can take hold.

How to deglamorize drugs? In a culture drenched in drugs, a few public service announcements are just not going to do the trick. As with tobacco, a successful campaign will require a measure of free speech restriction. Anyone for censoring marijuana-toking or cocaine- sniffing out of movies?

No? So what is left? What lies between jail and antidrug videos? Testing. Last month a presidential commission recommended drug testing for federal employees and strongly urged it for state and local government and the private sector.

Business seems to like the idea. About a quarter of Fortune 500 companies already have on-the-job drug testing, and that fraction will be up to a half by next year. They say it increases efficiency, job safety and productivity. But if efficiency, job safety and productivity are your real concern, then you test those employes who appear stoned on the job, or are falling down for reasons unknown, or are otherwise acting inefficiently and unproductively. You don't screen en masse.

Screening en masse has a different, larger reason. Whatever the motive of the individual employer, it is becoming society's preferred form of demand-side drug control. It carries the threat of a real, material sanction -- a sanction that hits you where it hurts, but doesn't quite put you in jail. It jeopardizes your job, but not your liberty. And is administered not by guys in blue suits with guns, but in white coats and gloves -- on orders not from a judge but from your boss. It violates the Fourth Amendment just the same, but seems so much more innocent. "Just checking."

Drug testing is an attempt to improve behavior, not production. It is not about economic efficiency. It is an extraordinary experiment in law enforcement.

And it is the coming approach to demand-side drug control. On the whole, it is the most sinister, as is all social control exercised by non-law enforcement agencies. The more disguised and benign such control, the more insidious. In fact, such techniques are a specialty of totalitarian societies. They rule not by the overt terror of the secret police -- most tin-horn dictators do that and they fall like flies, anyway -- but by far more subtle control: the local block committee, for example, run by a neighbor who controls your ration card and thus your speech.

Urine testing on the job is not of the same order of malignity, but it is the same idea. The time to stop it is now. It is, I admit, the most promising -- indeed, the only remaining -- means of drug-enforcement. But its price is very high.

In a culture that loves its drugs, the choice is as clear as it is unfortunate: liberty or drug enforcement. Choose liberty. Better to tolerate a loose trim on the Chevy that rolls off the Monday assembly line than to make Americans plead for their jobs, (plastic) cup in hand, before the state and its agents.