The removal of cannabis and cannabis resin from Schedule IV of the Single Convention on narcotic drugs is a change in international law that took place from 2019 to 2021, on the basis of a scientific assessment by the World Health Organization.

Since the United Nations adoption of the 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. Following the 2 December 2020, vote by the United Nations Commission on Narcotic Drugs, the removal of cannabis and cannabis resin from that Schedule entered into force in 2021. 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.

Under Article 3 of the Single Convention, the World Health Organization is mandated with assessing substances for their inclusion or move in, or withdrawal from the Schedules of the international drug control conventions. Within the WHO, the Expert Committee on Drug Dependence (or ECDD, previously called Expert Committee on "Habit-forming Drugs" and on "Drugs Liable to Produce Addiction") is tasked with the scientific evidence-based assessment of substances. But even before the Single Convention, the committee had this mandate under previous drug control treaties.

The ECDD first included cannabis on its agenda at its 3rd meeting (1952), and then again at its 4th (1953), 5th (1954), and 11th (1960) meetings, before the plenipotentiary conference was convened. They repeatedly concluded that "there is no justification for the medical use of cannabis preparations" and that "there should be an extension of the effort towards the abolition of cannabis from all legitimate medical practice." The assessments have been criticized for their lack of scientific methodology, and reliance on doubtful sources such as reports from South African police at times of the apartheid regime. On the basis of the conclusions drawn by the ECDD, the United Nations Conference on Narcotic Drugs decided to list cannabis and cannabis resin in Schedules I and IV, while listing "extracts and tinctures" only in Schedule I.

In 1970, a letter between U.S. Assistant Secretary of Health Roger O. Egeberg and U.S. congressman Harley O. Staggers suggests that many stakeholders saw the classification in Schedule I and IV of the convention as provisional:"Some question has been raised whether the use of the plant itself produces 'severe psychological or physical dependence' as required by a schedule I or even schedule II criterion. Since there is still a considerable void in our knowledge of the plant and effects of the active drug contained in it, our recommendation is that marijuana be retained within schedule I at least until the completion of certain studies now underway to resolve the issue." Text originally presented at the 12th International Conference on Drug Policy Reform.The "certain studies" refers to the anticipated findings of the National Commission on Marijuana and Drug Abuse. The Commission released a 1972 report favoring decriminalization. However, findings of the commission had no impact on the international scheduling of cannabis.

Previous demands for rescheduling There has long been some controversy over whether cannabis is "particularly liable to abuse and to produce ill effects" and whether that "liability is not offset by substantial therapeutic advantages", as required by Schedule IV criteria. Already in 1973, the Commentary on the Single Convention edited by UN Secretary-General pointed out that "should the results of the intensive research which is at the time of this writing being undertaken on the effects of [cannabis and cannabis resin] so warrant, they could be deleted from Schedule IV, and these two drugs, as well as extracts and tinctures of cannabis, could be transferred from Schedule I to Schedule II."

Since the discovery of the endocannabinoid receptor system in the late 1980s, which revolutionized the scientific understanding of the psychopharmacological effects of cannabis, and the important progresses in research related to the medical uses of the plant, questions as to the validity of the placement of cannabis and cannabis resin in Schedule IV increased, seen as representing "a historical anomaly [that] should be reviewed at the earliest opportunity".

In the United States, there has been a number of lawsuits over whether cannabis' Schedule IV status under the Single Convention requires total prohibition at the national level (such as NORML v. Ingersoll 497 F.2d 654 in 1974 or NORML v. DEA 559 F.2d 735 in 1977). In the 2000s, members of the European Parliament such as Kathalijne Buitenweg criticized the Single Convention's cannabis scheduling regime. In 2011, a Canadian Senate committee report noted that:"The argument for placing cannabis in [Schedule IV] was that it was widely abused. The WHO later found that cannabis could have medical applications after all, but the structure was already in place and no international action has since been taken to correct this anomaly." The United Nations Committee on Economic, Social and Cultural Rights emphasised in 2020 that the placement of cannabis in Schedule IV had not been validated by any scientific assessment.

Mandates for a scientific assessment In fall 2016, NGOs sent open letters to WHO Director-General Margaret Chan, urging her to include cannabis as a review agenda item at the next ECDD meeting.Ghehiouèche, F. (2016). Summary: Mailing action to ask for an amendment of the agenda of the Expert Committee on Drug Dependence 38th meeting. One of the NGOs which sent the letter was in official relation with the WHO, making of its demand a mandate for the ECDD to comply with. Nonetheless, in previous years, several bodies entitled to mandate a scientific review of cannabis by the ECDD had already requested it to do so:"the CND in 2009 (CND Resolution 52/5), the INCB in 2014, the ECDD itself in 2015, from the Czech republic in 2016 at the 69th World Health Assembly"In addition, the Caribbean Community also requested an ECDD review of cannabis, although in a report that was only published in 2018, after the review process had started.

Scientific assessment by the World Health Organization The scientific assessment was initiated in December 2016 with the announcement at the Commission on Narcotic Drugs by ECDD secretary, Dr Gilles Forte. The ECDD vowed to pre-review cannabis "within the next eighteen months from the 38th meeting" which was held in November 2016.

Review process The scientific assessment of substances is divided in two steps: pre-review and critical review. According to the WHO:"The purpose of the pre-review is to determine whether current information justifies an Expert Committee critical review. The categories of information for evaluating substances in pre-reviews are identical to those used in critical reviews."As compared with the original assessments of cannabis from the 1950s "hastily drawn up on the back of an envelope, the methodology, quality of work and mechanisms for the review of substances considered for international control have evolved substantially" when the ECDD started to collect data towards a pre-review. The ECDD dedicated special attention to the assessment of various products from the Cannabis plant, which were divided as follows:

Cannabis plant and cannabis resin Extracts and tinctures of cannabis Delta-9-tetrahydrocannabinol (THC) Cannabidiol (CBD) Isomers of THC.

A total of 3 ECDD meetings were involved with the assessment:

From 6 to 10 November 2017 (39th meeting), the ECDD undertook a pre-review of CBD. From 4 to 7 June 2018 (40th meeting), for the first time, the ECDD dedicated a meeting only to the assessment of cannabis-related substances, with: the critical review of CBD, the pre-review of the 4 other products and substances. From 12 to 16 November 2018 (41st meeting), the critical review of the remaining 4 cannabis products and substances.