In 1925, there was an international conference on drugs which focused particularly on opium. But it also looked at Cannabis sativa. Egypt was the chief mover in persuading other nations that Cannabis sativa should be banned.
Egypt had a long history of using Cannabis as a drug. As a Muslim country, it also had a long history of attempting to prohibit its use. And Egypt in the 1920s, like the United States, was a great producer of cotton, a rival textile to hemp.
In the United States, the prohibition of Cannabis (dubbed "marijuana") occurred in 1937, following a long campaign by newspaper publisher William Randolph Hearst. It came in as the prohibition on alcohol was lifted.
Alcohol was, of course, the whites' preferred drug. Marijuana, as Hearst reiterated in his many papers, made blacks disrespectful and violent towards whites, and gave black males "ideas" about white women. He enlisted the support of racist white organisations in his campaign. And his friend Harry Anslinger, the director of the Bureau of Narcotics, did not lose his job when alcohol was legalised: there was this convenient new prohibition to enforce.
Some of the other characteristics of this plant may also provide clues to the motives that condemned Cannabis.
In its Latin name, sativa may be translated as "satisfying". And indeed it did satisfy a wide range of human needs in much of Eurasia (it probably was native to India, southern Siberia, southern Russia and China) for aeons, before making its way via trade routes to Africa and Europe. It was part of the great common of useful and easy to grow food plants of the old world.
It has long, tough fibres in the stems — this makes it an ideal source of textile material.
It also contains a number of alkaloids that have powerful pharmaceutical properties.
These two characteristics are found both in true Cannabis, and in the native American equivalent, Apocynum cannabinum (meaning Cannabis-like Apocynum). The common names of these plants are, respectively, Indian hemp and American hemp. American hemp has never been prohibited. On the other hand, it does not ever seem to have been cultivated and may well be less easy to grow than Cannabis sativa.
From these two characteristics came practical uses: it is estimated that, as a source of textile fibre, Cannabis was used for at least 10,000 years. It is as old as pottery, older than metal-working. String, rope, sacking — all were of hemp, or hemp mixed with other fibres.
To get the best and longest fibres, the plants are grown close together. Cannabis sativa can reach 4-5 metres in height. When full-grown, the stalks are cut and water-rotted, then beaten to release the fibres. These stalks contain only small traces of the alkaloids.
The cultivation of hemp as a source of fibre spread across Asia, Africa and Europe. Italy was a major source of hemp imported to England, for example, for use in clothes, tents, sails, linen, drapes, quilts, sheets and towels. It was not until the invention of the "cotton gin" (meaning cotton engine) in the 1820s that cotton became as economical as hemp for textile fibre.
Not as old as its use in textiles is the use of Cannabis for paper, but the Chinese have made paper from hemp fibre for 2000 years. Until 1883, most European paper was made from recycled hemp fibre — rags and worn-out sails. At the time of Cannabis prohibition, paper manufacturers had invested heavily in processes and machinery for converting wood to paper cheaply. Also in the 1930s, machinery for processing hemp was developed which would have made raw hemp fibre an even cheaper source of paper pulp than wood. Surely there is, in this paper connection, the long shadow of William Randolph Hearst?
The seeds of Cannabis sativa, like the stalks, contain no significant quantities of alkaloids. Before 1800, hempseed oil was the most common lighting oil in the world. It was also used for cooking and later for engine lubrication. Paint and varnish used always to contain either hempseed or linseed oil. In 1935, the United States used 58,000 tons of hempseed oil. After hemp prohibition, DuPont petrochemicals inherited this market.
As a source of food, hemp is coarse but highly nutritious. The pressed seeds make a high-protein cake for animals or humans. The seeds can be sprouted and eaten, or ground into flour.
As a source of combustible fuel, Cannabis sativa is the fastest-growing source of biomass on the planet. It releases no sulphur or lead when burned, and grows better with more ultraviolet radiation.
It is only the leaves, flowering tops and exuded gum on the hairs of these that contain significant amounts of the alkaloids for which prohibition was imposed. To encourage the production of these, the plants are spaced widely and encouraged to branch.
The medicinal and mood-altering properties of the plant have also been known since ancient times. Its many names include "Cementer of Friendships", "Leaf of Delusion", "Increaser of Pleasure", "Poor Man's Heaven". For these effects, the leaves were smoked or infused as "tea"; the sticky gum from the flowering tops was combined with honey or baked into cakes and eaten.
The drug was used to treat a wide range of physical and psychological disorders, by the Chinese, the Indians and the ancient Greeks. It was noted from earliest times that the drug heightened or intensified mood: thus it was effective in inciting fanatics to murder (our word "assassin" is derived from the word "hashish"), as well as in augmenting calm.
The drug was not much used in northern Europe, perhaps because the leaves quickly lose their potency with storage, until the return of Napoleon's armies from Egypt and the establishment of the British in India. Eminent French and British doctors reported on its effectiveness in relieving pain without the undesirable side effects of alcohol or opiates. It became, after alcohol and opium, the most common ingredient in patent medicines in 19th century Western Europe.
Surely, the makers of alcoholic beverages and the producers of tobacco and cigarettes would not have been displeased to have easily grown and cheaply available competition eliminated by this ban. The nascent pharmaceutical industry, whose new drugs like aspirin were being heavily promoted, would also have stood to profit by the change.
So it may be that the health and moral grounds on which, ostensibly, the cultivation of Cannabis sativa was prohibited are firmly underpinned by the profit motive of a number of commercial interest groups. It is dubious that the prohibition has been in any way beneficial to anybody except these interest groups and criminal profiteers. It is likely that its prohibition has deprived many of the world's poor of a useful subsistence crop.