The United Nations and national governments the world over, including Canada's, are actively promoting an epidemic. They are infecting people by the tens and hundreds of thousands. God knows how many will die.

A report released this week by the Global Commission on Drug Policy isn't quite that blunt, but it comes close. "The global war on drugs is driving the HIV/AIDS pandemic among people use who drugs and their sexual partners," it concludes. "Throughout the world, re-search has consistently shown that repressive drug law enforcement practices force drug users away from public health services and into hidden environments where HIV risk be-comes markedly elevated. Mass incarceration of non-violent drug offenders also plays a major role in increasing HIV risk. - The war on drugs has also led to a policy distortion whereby evidence-based ad-diction treatment and public health measures have been downplayed or ignored."

Among most drug policy re-searchers and public health officials, that paragraph is no more controversial than saying smoking causes lung cancer. But the members of the Global Commission include former presidents of Brazil, Mexico and Colombia. And George Schultz, the U.S. secretary of state in the Reagan administration. And Paul Volcker, the near-legendary former chairman of the U.S. Federal Reserve. And Canada's Louise Arbour, a former Supreme Court justice and former UN High Commissioner for Human Rights. It's extraordinary to have people of that back-ground and stature agreeing in public that, as the report put it, "the war on drugs has failed and millions of new HIV infections and AIDS deaths can be averted if action is taken now."

But, as excellent as the report is, it omits a critical piece of the puzzle.

Why do users take drugs by intravenous injection?

After all, drugs can be swallowed, inhaled or smoked. Each of these methods is inherently more pleasant than sliding a sliver of cold steel into a vein. What's more, each of these methods is less likely to result in overdose. Each is less likely to result in abscesses or bacterial infections of the heart. And each involves little or no risk of transmitting blood-borne diseases like hepatitis and HIV.

So why do people use the most unpleasant and dangerous method?

If you look around today, you would say it's just part of the illicit drug culture. If you hook up with someone who injects, that's how you learn to take drugs, and, in time, you become habituated to it. Users may even come to feel affection for the little rituals involved in preparing the needle. So that's why they do it.

But that answer simply pushes the question back a little further: When and why did the most unpleasant and dangerous method of taking drugs become widespread?

In the 19th century, currently illicit drugs were legal. Some-times people mixed them with alcohol or tea and drank them.

Sometimes they smoked them. And occasionally they injected drugs, especially morphine, a more-potent derivative of opium.

But drugs weren't injected in-to the veins. Instead, following the medical practice of the day, these were subcutaneous (below the skin) injections. "No one seems to have injected morphine intravenously until the 20th century," writes historian Richard Davenport-Hines in The Pursuit of Oblivion: A Global History of Narcotics.

We know roughly where and when it started. It was 1925. In Terre Haute, Indiana. That's the earliest known account of intra-venous drug use. From there, the habit spread like a virus. In 1935, almost half the addicts ad-mitted to an American drugtreatment hospital were doing it. By the early 1950s, injection had become so routine that when a heroin panic swept North America - immortalized by Frank Sinatra in The Man With The Golden Arm - the needle symbolized the threat.

So what caused this dramatic change in users' behaviour? Drugs were criminalized.

Banning drugs didn't wipe them out. It merely shifted their sale to the black market. That had two immediate effects.

First, the available drugs tended to come in more potent forms for the simple reason that smuggling a highly potent drug is easier than smuggling the same drug in less potent form. Imagine having to choose between smuggling a case of vodka or several kegs of beer and you get the idea. As a result, opium was increasingly replaced by morphine and its even more potent chemical cousin, heroin.

The other thing the switch to the black market did was raise the price by as much as 10 times or more. Inevitably, users be-came very concerned about the efficiency of the method by which they took the drug: They had to get the "the most bang for the buck." So forget eating or drinking the drug. That's the most inefficient method. Smoking is better. So is inhaling.

But the most efficient method of all, by far, is intravenous injection.

Out went opium smoking and the other, safer 19th-century methods of drug consumption. In came heroin injection.

Something like this pattern can be seen whenever drugs were banned.

Opium had been smoked in Thailand for centuries. But in 1959, at the insistence of the United States, the Thai government banned it. Heroin injection appeared and spread al-most immediately, so, when AIDS arrived in the 1980s, it raced from one needle to an-other, producing one-third of new infections.

Now I have to confess that I've plagiarized myself here. I wrote almost everything in this column a decade ago. But that underscores the point, doesn't it?

All of this has been known for years. Even decades. The science writer Edward Brecher laid out much of it in 1972.

But entire generations of politicians have simply refused to examine the evidence and re-consider their policies. Even on something as relatively simple as the efficacy of Insite, the Vancouver injection site, Stephen Harper, Dalton McGuinty, Jim Watson and a long list of other politicians have steadfastly re-fused to take a serious look the evidence and talk about it. It's hard to imagine any of them having the intellectual honesty and political courage to call for a royal commission into the whole bloody mess.

But who knows? Sometimes, even when it's least expected, change happens. Maybe the Global Commission on Drug Policy is a straw in the wind.

I sure hope so. Nothing would be more depressing than writing this column again a decade from now.