Cannabis prohibition timeline

TL;DR

• 1925: Geneva Convention added cannabis under Egyptian pressure.
• 1937: US Marihuana Tax Act (Anslinger).
• 1961: UN Single Convention placed cannabis in Schedule IV (strictest).
• 2020: UN removed cannabis from Schedule IV following the WHO-ECDD recommendation.

1925 – 1961: the foundations

The 1925 inclusion of 'Indian hemp' was the global starting point. The 1961 Single Convention cemented cannabis as a Schedule IV substance — on par with heroin (Bewley-Taylor 2014).

2020: the UN rethink

On 2 December 2020 the UN Commission on Narcotic Drugs voted 27-25 to remove cannabis from Schedule IV — a historic if limited step that eases medical research.

The Swiss perspective on the history of prohibition

Switzerland looks back on an independent development in cannabis legislation, which was heavily oriented towards international agreements but also took pragmatic, independent paths. The Narcotics Act established the legal framework regulating the handling of psychoactive substances. In the late twentieth century, social debates led to a more nuanced perspective. A decisive step was setting the limit of less than one percent total THC, which clearly sets Switzerland apart from the more restrictive legislation of many European neighbouring countries and enabled a legal market for CBD products.

In recent years, Swiss drug policy has moved further towards harm reduction and scientific evidence. Since August 2022, medical cannabis can be prescribed directly by the medical profession without an exceptional permit from the Federal Office of Public Health, which significantly facilitates patient access. In parallel, the legally anchored pilot trials in various Swiss cities allow for the controlled dispensing of recreational cannabis. These scientifically monitored projects are intended to provide sound data for a future, regulated dispensing policy, while a strict zero-tolerance policy continues to apply in road traffic.

• Setting the limit for legal hemp at less than 1 percent total THC.
• Facilitated access to medical cannabis preparations since August 2022.
• Conducting time-limited pilot trials for regulated dispensing in Swiss cities.
• Strict unfitness to drive in road traffic from a limit of 1.5 micrograms of THC per litre of blood.

The administrative mechanisms of global control

The global prohibition regime established itself through a close-knit network of international treaties that demanded strict implementation in national law from signatory states. By classifying cannabis into the most restrictive control schedules, member states were bound under international law to limit the cultivation, trade, and possession of the plant exclusively to medical and scientific purposes. Compliance with these requirements was henceforth monitored by international control bodies, which for decades exerted enormous diplomatic pressure on countries considering reforms or decriminalisation.

These administrative hurdles blocked not only the legal market but also scientific research into the plant. Because researchers had to undergo extremely strict licensing procedures to obtain and use cannabis for research purposes, knowledge about the mechanism of action of cannabinoids remained incomplete for a long time. This lack of clinical trials was in turn used by regulatory authorities as an argument to maintain the restrictive classification. Only the gradual liberalisation in some countries made it possible to slowly break this regulatory cycle.

• Obligation of nation states under international law through the UN drug conventions.
• Monitoring of national legislation by global control bodies.
• Decades of obstruction of medical research by bureaucratic hurdles.
• Preservation of prohibition due to the lack of standardised scientific data.

The change in the 21st century and the socio-cultural shift

At the beginning of the twenty-first century, the global prohibition model began to increasingly show cracks. Driven by patient associations, new scientific findings, and the obvious failure of repressive measures to curb the black market, the first states began looking for alternative paths. The realization that the criminalisation of consumers causes significant social costs without effectively reducing consumption led to a reassessment. The first regions began to decriminalise the possession of small quantities and to focus on prevention and youth protection.

The transition from pure decriminalisation to state-controlled regulation marks the most modern phase of this development. While decriminalisation merely suspends the prosecution of consumers, regulation aims to monitor the entire supply chain from cultivation to sale under state supervision. This enables seamless quality control, the determination of active ingredient content, and the exclusion of contaminants. Modern regulatory approaches therefore increasingly view cannabis as a health policy issue rather than primarily a matter for law enforcement agencies.

• A shift away from purely repressive measures towards harm reduction approaches.
• Distinction between the decriminalisation of consumption and the regulation of the market.
• Focus on state quality controls to protect consumers from contamination.
• Increasing establishment of health policy prevention programmes instead of penalties.

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