When Rosie Boycott, the then editor of The Independent on Sunday, launched her campaign for the decriminalisation of cannabis in 1997, the decision caused a furore.
At the start of the campaign, Ms Boycott wrote: "Certainly, no one has ever been disfigured by a joint. The truth is that most people I know have smoked at some time or other in their lives. They hold down jobs, bring up their families, run major companies, govern our country, and yet... cannabis is still officially regarded as a dangerous drug."
Just a few months later, on Saturday 28 March 1998, thousands of supporters gathered in Hyde Park. Ms Boycott was pictured pushing a wheelchair-bound MS sufferer who used the drug to ease the symptoms of his condition. The campaign had secured the support of celebrities such as Sir Paul McCartney, Martin Amis, Harold Pinter, Nick Hornby, Peter Gabriel and Anita Roddick. They were joined by scientists, lawyers, academics, doctors and artists.
The following year the British Medical Association and the House of Lords Scientific Committee both agreed that cannabis had medical properties, and in 2004, the then Home Secretary David Blunkett effectively relaxed the laws over cannabis by reclassifying it as a class C drug.
When the IoS launched its campaign, the main focus of concern was over drugs such as ecstasy. Although there had been those who had started voicing concerns over cannabis use, a lack of scientific research meant that the dangers went largely unheeded.
But with the growing number of studies being published linking skunk cannabis to disorders such as psychosis and schizophrenia, the debate has moved on. Although the actual numbers of people taking cannabis seem to have levelled off, that still means more than 1.5 million Britons have used the drug.
However, concern is increasing among experts about the mental health risks, particularly in the case of teenage users who are smoking home-grown skunk that they say has about as much relation to the cannabis of years gone by as shandy does to brandy. As we report on our front page, more than 10,000 teenagers needed treatment for cannabis addiction last year.
In 2001, the Advisory Council on the Misuse of Drugs had already concluded that there could be a link between cannabis use and the onset of psychotic illnesses. Although conclusive evidence does not exist, several studies have suggested that there may be a further association between smoking cannabis in adolescence and mental illness in later life.
Some of the most prominent supporters of the campaign are now reassessing their stance. Professor Colin Blakemore, head of the Medical Research Council, said: "Yes it is certainly true that there is more evidence of the link between heavy cannabis use and cases of psychosis in certain vulnerable individuals, particularly younger people, than there was 10 years ago. I am not sure that the legalisation of one iconic drug like cannabis is necessarily the way forward. We should instead focus our attention on overhauling the whole classification system.
"The link between cannabis and psychosis is quite clear now; it wasn't 10 years ago. When discussing drugs you have to have special concern for young people."
Paul Flynn MP, another of the original supporters of the campaign, said: "My view is exactly the same. Prohibition doesn't work. It's much worse to have the market controlled by dangerous criminals than for it to be properly controlled."
Others are not so sure. Professor Nick Heather of Northumbria University said: "I would not have the confidence to join a campaign such as that now."
Some, such as Carmen Calill, author and founder of Virago Press, are now opposed to legalisation. "I wish people wouldn't do it, but I don't want to stop them. I do want to stop politicians having anything to do with it, though, so on balance I am now against its legalisation," she said.
But Caroline Coon, artist and founder of Release, said: "The prohibition of drugs like marijuana is immoral in principle and unworkable in practice. Precisely because drugs can be dangerous, they should be licensed and controlled and brought within the law."
The drug receptors
Cannabinoids act on a specific protein receptor in the brain, interfering with concentration, memory and pain perception
The pleasure zone
Tetrahydrocannabinols (THC), the active constituent of cannabis. THCs can pass across the biological barrier that separates the brain from the bloodstream, and in doing so penetrate the central nervous system. Here, they act on the natural proteins or receptors that control nerve impulses passed from one part of the brain to another
The body map
Brain: short-term memory loss; increased risk of psychosis or schizophrenia
Lungs: increased risk of lung cancer
Heart: raised pulse rate puts pressure on heart
Liver: lower blood pressure can affect internal organs
What we said then - and what we know now
Today, The Independent on Sunday calls for the personal use of cannabis to be decriminalised. The paper's campaign will continue until the law is changed and possession of marijuana for personal use is no longer an offence
'IoS' leader 1997
The time has come to reverse one of the positions with which this newspaper was identified. The more the facts can be driven home about the differences between old-style hash and modern skunk, and the risks to mental health, the better
'IoS' leader TodayReuse content