How Colonialism Wrote the Rules of Global Cannabis Law

October 2, 2026

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Walk into a courtroom in Lagos, Nairobi, or Kingston and ask why cannabis is illegal there, and you'll rarely get an answer rooted in local medical findings or a homegrown public health campaign. More often than not, the law on the books traces back to a conference room in Geneva in 1925, or further back still, to a petition a colonial government filed in 1923 on behalf of an empire that no longer exists. Most countries never debated cannabis on their own terms. They inherited a verdict.

That verdict has a surprisingly specific point of origin: a request from Jan Smuts's South African government to add cannabis to an international schedule of habit-forming drugs, years before most of the world had any unified drug policy at all. The petition became the direct ancestor of prohibition statutes across dozens of countries that copied colonial legal codes wholesale at independence and never got around to rewriting them. The irony sits right at the center of the story -- the same administrations pushing criminalization abroad were often cultivating, taxing, or exporting the plant themselves, and when they commissioned their own research into its effects, as Britain did in India in 1894, the findings undercut the very policy they went on to pursue anyway. A hundred years later, South Africa closed its own loop, legalizing in 2024 almost exactly a century after its government first asked the world to ban the plant it would eventually bring back home.

The 1923 Petition That Changed Everything

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Jan Christiaan Smuts governed South Africa through a period of intense anxiety about labor, race, and social control, and in 1923 his administration brought that anxiety to the League of Nations. The ask was narrow on paper -- add cannabis to the list of habit-forming drugs subject to international oversight, alongside opium and its derivatives -- but the framing behind it was unmistakable. South African delegates described dagga use as a corrosive habit among Black and Indian laborers, the kind of vice that threatened productivity and order on mines and farms, not a question of pharmacology or public health in any clinical sense.

Egypt and Turkey picked up the same argument and pushed it further at the international level, warning that hashish consumption was spreading social decay through their populations. Together these delegations built enough momentum that cannabis landed on the agenda of the 1925 International Opium Convention in Geneva, where it was formally added to a controlled drug schedule for the first time in the history of international law. No scientific commission had been convened to study the plant beforehand. The decision moved through diplomatic channels, shaped by the same men who ran colonial administrations back home.

Britain felt the pressure to align its own statutes and passed the Dangerous Drugs Act of 1929, criminalizing cannabis throughout England and setting an expectation that colonial territories would follow the metropole's lead. Many did, sometimes within a few years. What's striking is how openly racialized the original South African debate had been -- officials weren't shy about naming which groups they meant to control, and the language of the petition reads less like a health document than a labor-management memo with legal teeth attached.

Profiting From the Plant While Banning Its Use

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Colonial administrators rarely saw a contradiction in condemning cannabis use while eyeing cannabis cultivation as a resource worth developing. Henry Morton Stanley, mapping and administering territory in the Congo Free State, catalogued cannabis among the crops he believed local populations could be organized to grow and sell at scale, treating it as a potential export commodity in the same breath he complained about his own porters smoking it along the expedition route. The plant was valuable going out and suspect coming in -- a split that shows up again and again across different empires.

British, French, and Portuguese territories all followed some version of this pattern. Hemp fiber and cannabis as a trade good carried real economic weight, worth encouraging through taxation schemes or licensed cultivation. Smoking or chewing it, meanwhile, got filed under native vice, something to be policed rather than studied, unless the study was convenient to commission and then convenient to ignore.

That's exactly what happened with the British Indian Hemp Drugs Commission of 1894, one of the most thorough drug studies of the entire colonial period. Investigators compiled 3,281 pages of findings built on testimony from nearly 1,200 witnesses -- doctors, religious figures, farmers, law enforcement officers, and users themselves -- across the Indian subcontinent. Their conclusion was blunt by the standards of the era: moderate use of cannabis produced practically no ill effects, and the case for broad prohibition didn't hold up against the evidence collected.

The British government shelved it. Rather than loosening restrictions in response to its own commission's findings, colonial policy in India hardened over the following decades, and by the time international pressure from Geneva arrived in 1925, nobody in the imperial bureaucracy seemed inclined to revisit a report that had already been sitting on a shelf for decades.

Ganja, Indenture, and Jamaica's Long Road Back

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Cannabis reached Jamaica through a very specific historical channel: indentured laborers brought from India after the abolition of slavery in the British Caribbean, arriving through the mid-19th century and bringing ganja with them as part of daily and religious life. For decades it moved through Jamaican society largely outside the reach of formal law, used across communities descended from both African and Indian laborers.

That changed with the Ganja Law of 1913, pushed through with backing from the island's white planter class and the Council of Evangelical Churches, which treated the plant as a threat to social order in terms that echoed the language coming out of South Africa and Geneva around the same period. The law criminalized possession and cultivation outright, and enforcement fell disproportionately on poor and working-class Jamaicans.

The timing mattered enormously for Rastafari, a faith that took shape in Jamaica and incorporated ganja as a sacrament central to meditation and worship. Because the 1913 law was already on the books, Rastafari practitioners were criminalized from the movement's earliest years simply for practicing their faith as intended, a legal bind that persisted through most of the 20th century regardless of how the movement's cultural standing shifted internationally.

Substantive reform didn't arrive until the Dangerous Drugs Amendment Act, passed by Jamaica's Parliament on February 6, 2015, and granted royal assent on March 20, 2015. The law decriminalized possession of small amounts and, notably, carved out explicit exemptions for Rastafarian religious use, something that had been denied for over a century. The gap between the original criminalization and that reform runs close to a hundred years, a span during which the colonial administration that wrote the 1913 law was long gone, but its statute kept functioning exactly as designed.

South Africa's Hundred-Year Loop

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South Africa's path to cannabis law didn't begin with Smuts's 1923 petition to Geneva -- it began with local ordinances in Natal and the Cape Colony that criminalized dagga use among African and Indian laborers years earlier. Those colonial-era rules fed directly into the country's first nationwide prohibition, enacted in 1922, a full year before the government took the matter to the League of Nations and helped shape international law around it.

Enforcement only tightened from there. Under apartheid, cannabis law became part of a broader architecture of social control, culminating in a 1971 statute sometimes described at the time as the toughest anti-drug legislation anywhere in the Western world. Possession carried severe penalties, and enforcement patterns tracked closely with the same racial lines the original colonial ordinances had drawn decades before.

The legal landscape didn't start shifting until 2018, when the Constitutional Court ruled in the Prince case that prohibiting private adult use and cultivation of cannabis violated the right to privacy under South Africa's post-apartheid constitution. That ruling forced lawmakers to act, though it took until 2024 for the Cannabis for Private Purposes Act to formally take effect, arriving almost exactly one hundred years after the 1922 ban it ultimately undid. The law made South Africa the first country on the African continent to re-legalize adult-use cannabis.

The loop isn't fully closed yet. As of early 2026, South Africa's Justice Ministry is still working through implementing regulations for the Act, with a public comment period that closed March 5, 2026. A legal challenge brought by activist Jeremy Gordin Prince, questioning the procedural validity of how the Act was passed, is scheduled for a hearing in July 2026. Separately, the country raised its legal hemp THC threshold tenfold, to 2%, under the Plant Improvement Act effective December 1, 2025 -- though commercial cannabis sales remain tightly restricted to medicinal licensing administered through SAHPRA, leaving a gap between what's legal to grow at home and what can actually be sold.

A Centenary Nobody Celebrated the Same Way

South Africa and Jamaica both took roughly a century to move from colonial-era cannabis prohibition to legal reform, highlighting the long-lasting grip of imperial drug policies across former British colonies.

2025 marked a hundred years since the Geneva Opium Convention first put cannabis under international control, an anniversary that activists and drug policy researchers started informally calling the Centenary of Cannabis Prohibition. Unlike most centenaries, nobody marked it with anything resembling a unified commemoration, because the legal landscape it produced never unwound evenly.

South Africa had just legalized adult-use cannabis the year before. Jamaica had made its move a decade earlier, in 2015, carving out room for Rastafari practice and decriminalizing small-scale possession. Meanwhile a long list of former colonies across Africa and Asia continue to enforce statutes that are, in structure, nearly identical to what colonial administrators wrote a hundred years ago -- same possession thresholds in spirit, same framing of cannabis as a social contaminant rather than a plant with documented medical and economic uses.

Line these jurisdictions up and the pattern isn't about drug science at all. Countries that got early, aggressive access to cannabis research -- like the 1894 Indian Hemp Drugs Commission -- didn't act on more lenient findings any faster than countries that never commissioned a study in the first place. What predicts a country's current cannabis law isn't its public health data; it's which colonial government wrote the first version of that law, and which communities that government was trying to police when it did. Nigeria, Kenya, and large parts of former French West Africa still carry restrictions dating to administrations that left power sixty or seventy years ago. The throughline across a century of divergent outcomes is control, not evidence, and the places that have moved away from it did so only after sustained domestic legal fights rather than any international reconsideration of the 1925 framework itself.

None of this unfolded as a grassroots public health movement responding to local evidence. It unfolded as a diplomatic export -- decided in a Geneva meeting room in 1925, drafted in colonial legal offices from Pretoria to Delhi to Kingston, and handed down to communities that had been using the plant for generations without anyone bothering to ask them first. The 1894 Indian commission proved that colonial governments were capable of gathering real evidence when it suited them. They just weren't obligated to act on it, and mostly didn't.

South Africa's arc from 1923 petitioner to 2024 legalizer is the clearest proof that these laws can be undone, but the timeline is sobering. It took a full century, an apartheid regime's collapse, and a Constitutional Court willing to root cannabis policy in a right to privacy that didn't exist when the original ban was written. Jamaica's reform took almost exactly as long, and it still only partially addressed what the 1913 law criminalized in the first place.

What's left is a patchwork rather than a resolved chapter. South Africa is still finalizing the regulations meant to make its own legalization function, with a court challenge pending over how the law was even passed. Dozens of other former colonies haven't touched their statutes at all. The Geneva legacy isn't history yet -- it's a set of open legal questions still being argued, country by country, roughly a hundred years after a handful of diplomats decided the matter without consulting anyone who actually grew or used the plant.