The removal of cannabis and cannabis resin from Schedule IV of the Single Convention on narcotic drugs, 1961 is a change in international law that took place in 2021, on the basis of a scientific assessment by the World Health Organization.
Since the adoption of the United Nations' Single Convention on Narcotic Drugs in 1961, cannabis and cannabis resin had been listed in Schedule IV, the most tightly restricted category, reserved for drugs that are "particularly liable to abuse and to produce ill effects" and whose "liability is not offset by substantial therapeutic advantages." Its initial placement in this category was not based on science, and no international scientific assessment had been undertaken until 2018. The removal of cannabis and cannabis resin from that Schedule entered into force in 2021, after a vote on December 2, 2020, by the UN Commission on narcotic drugs. Since 2021, cannabis and cannabis resin remain listed in Schedule I of the Single Convention, alongside extracts and tinctures of cannabis.
Cannabis in the Single Convention
Cannabis, resin, and extracts and tinctures
The Single Convention is the main international treaty related to Cannabis sativa L. and its products. In its Article 1, the Single Convention defines "cannabis" as the "flowering or fruiting tops of the cannabis plant (excluding the seeds and leaves when not accompanied by the tops) from which the resin has not been extracted, by whatever name they may be designated;" while "cannabis resin" is defined as "the separated resin, whether crude or purified, obtained from the cannabis plant." At the adoption of the Convention in 1961, cannabis and cannabis resin were listed in both Schedule I and Schedule IV.
Schedule I includes substances that are highly addictive and highly liable to substance use disorders, or that are convertible into controlled drugs, while Schedule IV lists "certain drugs listed in Schedule I that are highly addictive and highly liable to abuse and rarely used in medical practice." Schedule IV is a "stricter subset of schedule I, that specifies extra control measures."
Cannabis plant, cannabis leaves, and cannabidiol
The "cannabis plant" is defined as "any plant of the genus Cannabis" but has never been listed in any Schedule. Only cannabis and cannabis resin are listed in the Schedules of the Single Conventions. Since "drugs" are defined as those substances listed in the Schedules, "cannabis plant" is not considered a drug according to the Single Convention.
The "leaves" of cannabis plants are in a similar case: while it is not listed in the Schedules, and is therefore not a "drug" in the meaning of the Single Convention, "cannabis leaves" are subject to some light measures of control under Article 28 of the convention.
Since only "cannabis," "cannabis resin," and "extracts and tinctures of cannabis" are listed in the Schedules of the Single Convention, some analysts and governments consider that cannabidiol (CBD) is not a "narcotic drug" in the meaning of the Single Convention, while others such as the International Narcotics Control Board consider that actual CBD products are in fact extracts of cannabis and should therefore be considered as Scheduled.
Tetrahydrocannabinol
delta-9-THC (tetrahydrocannabinol, or dronabinol) is not listed in the Schedules of the Single Convention but in the Schedules of a distinct treaty: the Convention on Psychotropic Substances of 1971. It has its own scheduling history: delta-9-THC was downgraded from Schedule I to Schedule II of the 1971 Convention in 1991, while other isomers of THC (such as delta-8-THC, delta-10-THC, etc.) remained in Schedule I.
History
Inclusion in Schedule IV
Although treaties preceding the Single Convention "contained the first provisions related to cannabis prohibiting the export of cannabis resin to countries that prohibited its use [...], however, no international attempts were made to control the traditional use of cannabis."
In 1961, the UN Economic and Social Council convened a Plenipotentiary Conference of 73 nations for the negotiation and adoption of the Single convention on narcotic drugs. That meeting was known as the United Nations Conference on Narcotic Drugs.