The NSW upper house is considering the medical use of cannabis. This reflects increasing recognition of the benefits of marijuana use in some cases, and comes after dramatic changes in the US where 18 states now allow it in certain circumstances - a milestone in undoing the catastrophic experiment known as drug prohibition.

In the 19th century there was little distinction between medical and non-medical uses of drugs. Australians had the highest consumption of ''patent medicines'' in the world. Preparations containing alcohol or opium were freely available from chemists and grocers. Cough medicines were laced with opium, morphine, or (later) heroin. Joy promised ''immediate relief in cases of asthma, cough, bronchitis, hay-fever, influenza and shortness of breath''. They were marijuana cigarettes.

By the time cannabis use expanded in Australia in the 1960s, a climate of moral hysteria was already entrenched. Credit:AP

Although outrageously hyped, such products satisfied a multitude of needs, physical and mental. They were used in the relief of all manner of pains, they calmed and they comforted. Little distinguished therapeutic use relaxation, relaxation from habit, or habit addiction. In 1868 Marcus Clarke even experimented with cannabis to see if it had beneficial effects on his creative imagination. It's hard to tell.

Attitudes to marijuana changed in this country during the first half of the 20th century. It did so under two main influences. First, American puritanism led to the rigorous control of one drug after another.