Introduction

The 2020s decade was opened by a change in the legal status of Cannabis sativa L. and some of its products, after half a Century of stand-still: on 2 December 2020, the Commission on Narcotic Drugs (CND; the prime policymaking body of the United Nations (UN) responsible for Cannabis -related matters) voted upon scheduling recommendations of the Expert Committee on Drug Dependence (ECDD) of the World Health Organization (WHO).
The ECDD is the only body with a treaty mandate to carry out scientific assessment of drugs and recommend scheduling changes (WHO, 2018); its recommendations sketched a number of changes in the legal control applying to “medical cannabis” under the international drug control Conventions (Mayor, 2019; Riboulet-Zemouli and Krawitz, 2022). But that change was only the latest development in a complex and convoluted history of multilateral controls applied to medicinal Cannabis , plant and products.
Research has seen, in recent decades, a renewed interest in the historiography of the placement of Cannabis within the framework of international drug control and its different legal instruments. In particular, scholarship has focused either on (1) the inception (the lead to the International Opium Convention of 1925 (C25) which incorporated some provisions related to “Indian hemp”[1]/haschish  alongside coca/cocaine and poppy/opium; Collins, 2021; McAllister, 2000; Mills, 2016) or (2) the immediate period leading to the adoption of the Single Convention on narcotic drugs in 1961, in the aftermaths of the second world war (WWII). Surprisingly, however, the two decades running between 1925 and the end of WWII have received very little scrutiny.
This 20-year gap in the history of Cannabis control became apparent in 2014, during the early preparations of the ECDD cannabis assessment process, when a particular episode surfaced and was labelled as an apparently key moment of that history:
“Cannabis and cannabis resin has not been scientifically reviewed by the Expert Committee since the review by the Health Committee of the League of Nations in 1935 […] which recommended that preparations obtained from cannabis extract or tincture were placed under control of the second Opium Convention” (WHO, 2014, p. 3).
This quote, extracted from the preparatory documentation of the 2014 ECDD meeting, only presents one single reference to back the 1935 event:The Genesis of International Control of cannabis – 1912 to 1978 , an internal document published by the International Narcotics Control Board (INCB) on 12 May 1978, with reference number E/INCB/W.22. Regrettably, this document is not listed (let alone conserved) in INCB or UN archival records.[2]
That “review by the Health Committee” of the League of Nations (LoN) in 1935 was arguably an important moment since it “recommended that preparations obtained from cannabis extract or tincture were placed under control.” But it has disappeared from the records.
Although some direct mentions of the 1935 review are found in late compilations of the works of the LoN (1945a, p. 187), the 1 860 bibliographical references about Cannabis compiled by UN Secretary-General in 1965 includes no mention of it (CND, 1965, p. 45). In the Bulletin on Narcotics , published by the UN, the article “Principal League of Nations Documents Relating to Narcotic Drugs” (1952) fails to reference any such event in 1935, similarly to important authors like Itsván Bayer and Hamid Ghodse (1999); only “The cannabis problem: A note on the problem and the history of international action” (1962) details that:
“Preparations made from extract or tincture of cannabis were not mentioned in the 1925 Convention, but in 1935 were brought within the control of the Convention by a decision of the Health Committee of the League of Nations under article 10 of the Convention.”
Note the difference between “a review” and “a decision” of the Health Committee…
By contrast, documents and meetings of the “Sub-Committee onCannabis sativa ” (a subsidiary organ under the “Advisory Committee on the Traffic in Opium and Other Dangerous Drugs” of the LoN) are extensively referenced. Most reviews of the early history of Cannabis control focus on this organ (Bewley-Taylor et al, 2014; Kozma, 2011b; The cannabis problem…, 1962). Yet, this Sub-Committee was not the organ invested with the mandate to review substances and recommend measures of control as appropriate (as the ECDD is nowadays): under the C25, such a task was mandated to the Office International d’Hygiène Publique of Paris (OIHP),[3] which informed the decisions of the LoN’s Health Committee. Yet, few publications reflect the role of –or indeed even mention– the OIHP.
Beyond the 1935 episode, the important drug control treaty functions discharged by the OIHP have been generally overlooked by observers, analysts, and historians. Key publications celebrating a Century of global drug control fail to mention the Office even once (Pietschmann, 2009; UN Office on Drugs and Crime, 2008).
After 2014, in the context of the assessments of Cannabis -related substances by the ECDD between 2016 and 2019 (Riboulet-Zemouli and Krawitz, 2022), additional mentions of the 1935 episode were made by scholars (Bewley-Taylor et al., 2016; Curran et al, 2016, p. 5; Danenberg et al, 2013 p. 177) and civil society stakeholders alike (International Drug Policy Consortium, 2018; Kazatchkine, 2016), without much clarity as to the content or outcome of what happened in 1935, however. In 2018, the authors of the present study found the minutes of the 1935 review meeting; they reproduced excerpts of it in a contribution to the 40th WHO ECDD meeting, commenting:
“The myth of an assessment of Cannabis under the LoN has justified the WHO shirking its responsibilities in the face of draconian measures of control, relying on a supposed previous ruling to avoid making decisions on a difficult subject” (Krawitz and Riboulet-Zemouli, 2018, p. 7).
This article seeks to document the context, stakeholders involved, content, and outcome of the 1935 review , and to ascertain the functions, mandates and dynamics of the world’s drug control organisation as it related to Cannabis and its products, in and around 1935.
To do so, after describing the approach used, the study introduces the legal regime of the time and the OIHP in the first subsection of the findings, before moving to a complete overview of the multifaceted organisational structure; the third and fourth subsections respectively analyse in detail the 1935 and 1938 episodes; a fifth subsection reviews the consequences over international works related to Cannabis after WWII, before discussing the findings in conclusion.