BBC Scotland's Morag Kinniburgh reports on the professor's call

Professor Donald Macleod is the second religious figure in Scotland to agree with Liberal Democrat leader Charles Kennedy's call for a Royal Commission to investigate drugs legislation.

Just days ago, the Most Rev Richard Holloway - Bishop of Edinburgh and Primus of the Scottish Episcopal Church - said he was in favour of an open debate and attacked what he described as the hysterical attitude towards drugs.

Prof Donald Macleod: Drugs policy "hopeless failure"

Prof Macleod, writing in the West Highland Free Press, described current drugs policies as hopeless failures.

He said they had not reduced demand, supply, crime or the number of deaths linked to drugs.

He said: "I do think it is quite illogical and hypocritical to be trying to criminalise cannabis and at the same time to be advertising and indeed packaging alcohol."

The professor believes the list of tolerated drugs should be reviewed as part of a thorough policy rethink.

He rejects the argument that using soft drugs lead to hard drugs because this omits alcohol and tobacco.

Royal Commission

The debate surrounding the legalisation of cannabis was back on the political agenda when Mr Kennedy, just days into his new role as leader of his party, said he wanted a Royal Commission to look at the whole treatment of drugs in Britain.

A commission into drugs has been Lib Dem policy for many years after being passed at the party's annual conference, but former leader Paddy Ashdown played down the issue.

Senior Scottish churchman Bishop Holloway has also made clear his views on the issue of using cannabis.

He says he wants young people to be taught how to use recreational drugs responsibly.

Richard Holloway: Call for responsible use

Bishop Holloway, who has admitted trying cannabis, said: "It seems to me that as long as it is handled in a responsible way and we teach our young people to live moderately and use these recreational substances moderately, then that is a wise policy."

But Prof Macleod's comments were condemned by the Scottish Conservatives.

Deputy leader Annabel Goldie said: "Representing as he does a church whose trenchant disapproval of alcohol is legendary, it seems bizarre to say the least that Prof Macleod should be supporting the legalisation of a substance which is now notorious for destroying families and has been, in many cases, the lead in to addiction to hard drugs.