The International Opium Convention, signed at The Hague on January 23, 1912, was the first international drug control treaty. The United States convened a 13-nation conference of the International Opium Commission in 1909 in Shanghai, China in answer to increasing criticism of the opium trade. The treaty was signed by Germany, the United States, China, France, the United Kingdom, Italy, Japan, The Netherlands, Persia, Portugal, Russia, and Siam. The meeting provided that “The contracting Powers shall use their best endeavors to control, or to cause to be controlled, all persons manufacturing, importing, selling, distributing, and exporting morphine, cocaine, and their respective salts, as well as the buildings in which these persons carry such an industry or trade.”
The Convention was implemented in 1915 by the United States, Netherlands, China, Honduras, and Norway. It went into force internationally in 1919 when it was included into the Treaty of Versailles. A revised International Opium Convention was signed on February 19, 1925, which went into effect on September 25, 1928. It introduced a statistical control system to be supervised by a Permanent Central Opium Board, a body of the League of Nations. Egypt, with support from China and United States, recommended that a prohibition on hashish be added to the Convention, and a sub-committee proposed the following text:
The use of Indian hemp and the preparations derived there from may only be authorized for medical and scientific purposes. The raw resin, however, which is extracted from the female tops of the cannabis sativa L, together with the various preparations of which it forms the basis, not being at present utilized for medical purposes and only being susceptible of utilization for harmful purposes, in the same manner as other narcotics, may not be produced, sold, traded in, etc., under any circumstances whatsoever. India and other countries objected to this language, citing social and religious customs and the prevalence of wild-growing cannabis plants that would make it difficult to enforce. Accordingly, this provision never made it into the final treaty. A compromise was made that banned exportation of Indian hemp to countries that have prohibited its use, and requiring importing countries to issue certificates approving the importation and stating that the shipment was required “exclusively for medical or scientific purposes.”