The Opium Convention of 1912, where a treaty was signed by China, Britain and ten other countries to prohibit opium use and trade, marked the start of the still-ongoing international effort to control the consumption of addictive-drugs through prohibition. The idea that opium was dangerous to both individual and societal well-being was a consequence of the popular but erroneous perception that unrestrained opium trade by Britain in the nineteenth-century had reduced the once-great Chinese civilization to an emaciated and hopeless population of opium addicts smoking themselves to death.
Opium was the most effective painkiller known to mankind before the discovery of modern medicines and had been imported into China for this medicinal property since the seventh century. With their better means of production that resulted in higher yields, the British traders supplied much more opium to China than the country had hitherto imported, thereby bringing the price of opium down to where even the poor Chinese could afford its regular consumption. This facilitated opium becoming a commonly-used panacea against the symptoms of a wide number of ailments and diseases. Medicinal use of opium also increased concurrently in Asia, the Middle East and Europe and the drug remained popular till modern medicines became cheaply available in the twentieth century. During the nineteenth century, the per capita consumption of opium was much greater in Britain than in China, but the British users did not suffer adverse effects on either their health or longevity. Moreover, there is ample evidence that most users of opium, including the Chinese, used it in moderation and only occasionally, such as when in pain.
The implementation of the 1912 treaty in China led to the public humiliation and imprisonment of tens of thousands of ordinary opium users. As most of these users were already ill, some with contagious diseases, the crowded prison cells became the breeding grounds of epidemics and had high mortality. Further, opium could now be obtained only in black market; scarcity and illegality made it expensive. A search for cheaper alternatives led most opium users to morphine and heroin, psychoactive substances that were much more addictive and were deleterious to health. The prohibition thus proved to be a cure that was worse than the disease.
(Adapted from the article written by historian Frank Dikotter www.opendemocracy.net and the book Narcotic Culture www.ncbi.nlm.nih.gov)