Today, Chinese authorities regard opium as a singularly bad thing. On this issue, mainstream opinion is as black and white as a panda. But, in Hong Kong, there has been a public debate - with shades of grey and layers of complexity - both historically and currently.

It was the communist revolution that erased opium from mainland China. Mao Zedong , with his political apparatus that reached into every hamlet and home, was able to lay the beast low. He used a mixture of carrot and stick. Addicts were not condemned, but offered medical help and rehabilitation. But those who were unco-operative were sent to labour camps or imprisoned. Dealers were summarily executed, often without trial.

China was clean for 40 years, until the demise of Maoism. But gradually, opium has returned. Now China is one of the world's most important opium growers, and its addict population exceeds 800,000. Although Beijing still regularly executes drug traffickers, demand in its freewheeling economic society finds willing suppliers prepared to take the risk. As a Chinese proverb puts it: 'If you open a window, sunlight comes in, but so do mosquitoes.'

Government attitudes in China have not changed. But the market is a match for the government, as it is almost everywhere. The black market grows by the decade, and suppression - unless it is utterly totalitarian - leaves enough loopholes for the determined to wriggle through.

The zeal for suppression has become counterproductive, building up the wealth and criminal reach of the drug barons. They have become so powerful that they often have a political influence that distorts and even threatens good governance. By all accounts, their influence is growing in most parts of the world, and the various types of control - from Europe's tolerance of soft drugs but toughness on hard ones, to China's rigorous policy on executing dealers - are clearly not working.

At least in Hong Kong, there is a reasonably informed and intelligent debate. On the mainland, as in many parts of America and Europe, debate is barely tolerated. In Hong Kong, it is understood that opium is not heroin and hashish is not crack.

Heroin addiction is in another league from opium. Hard drugs may be forbidden today in Britain and Hong Kong, but at least, unlike in America, there is no longer any debate about its medicinal uses. This is why it is probably best, if you have to die from some painful cancer - as my mother did - to do it in a hospice in Britain. It is one of the few countries to allow the use of heroin as a pain suppressant: it's the strongest painkiller of them all. The truth is that neither China, with its millennia of centralised government, nor the United States, with its technological prowess, is a match for the drug traders. The tough policies of China, Malaysia, Singapore and Thailand - who execute minor traffickers - have rarely touched the big barons.

We either do what Mao did - allow our governments to be totalitarian on this issue and implement a scorched-earth policy - or we legalise opium and other drugs to break the back of the underworld trade. We then deal with addiction by educational and medical means.

It is the current, and almost universal, in-between approach that is so unsatisfactory and dangerous.

Jonathan Power is a London-based journalist