A Century of Cannabis

Cannabis has had a tumultuous journey over the past 100 years, evolving from a widely used medicinal and industrial crop to a heavily regulated and, more recently, reconsidered product. We examine the significant milestones in cannabis history over the past century, focusing on the UK’s changing relationship with this versatile plant. Each decade has contributed uniquely to shaping public perception, scientific understanding, and legal frameworks for cannabis.

1920s–1930s: Early Prohibition and the Decline of Cannabis Use

The 1920s marked the beginning of global cannabis prohibition. The UK signed the International Opium Convention in 1925, which included cannabis for the first time. This decision was influenced by international pressure, particularly from countries with colonial interests where cannabis use was widespread. While cannabis had been used medicinally in the UK since the 19th century, this new classification began its decline.

By the 1930s, global sentiment towards cannabis had shifted further. The United States’ Marijuana Tax Act of 1937 reinforced negative perceptions of cannabis, portraying it as a dangerous drug. Although this legislation was not directly applicable to the UK, it significantly influenced British attitudes. During this period, industrial hemp farming also began to wane as alternative materials like cotton and synthetic fibres became more accessible.

1940s: Wartime Hemp Revival and Post-War Decline

The outbreak of World War II brought a brief revival of hemp cultivation in the UK. With shortages of essential materials, the government encouraged farmers to grow hemp for ropes, parachutes, and other wartime supplies. This initiative highlighted hemp’s industrial potential, but it was short-lived.

In 1942, cannabis was officially removed from the British Pharmacopeia, signalling its complete loss of status as a recognised medicine. This decision reflected broader shifts in medicine, with synthetic drugs like aspirin and barbiturates replacing traditional plant-based remedies.

After the war, industrial hemp production quickly declined, overshadowed by the rise of synthetic materials like nylon. The UK’s focus turned to economic recovery, and cannabis, both as a medicine and an industrial crop, faded into obscurity.

1950s: Reinforcing Prohibition and Anti-Cannabis Campaigns

The 1950s were marked by an intensification of global drug control efforts. The United Nations, driven by the United States and other major powers, launched campaigns to restrict cannabis use further. These efforts culminated in the UK introducing stricter regulations on cannabis cultivation and use.

During this period, cannabis became increasingly associated with criminality and moral decline. British society, influenced by media portrayals and government propaganda, began viewing cannabis as a dangerous substance. This era laid the groundwork for the punitive legal frameworks that would dominate the following decades.

1960s: Counterculture and the Beginning of Advocacy

a decade of cultural revolution, with youth movements challenging traditional norms and embracing alternative lifestyles. Cannabis became a symbol of counterculture, popularised by musicians, artists, and activists. In the UK, figures like The Beatles openly discussed their cannabis use, sparking widespread debate.

On the scientific front, Israeli chemist Raphael Mechoulam made groundbreaking discoveries by isolating and synthesising THC, the primary psychoactive compound in cannabis. This research laid the foundation for understanding the plant’s medicinal properties, though it would take decades for governments to acknowledge these findings.

The UK government maintained its hardline stance, despite growing public interest in the potential benefits of cannabis. In 1961, the UK signed the Single Convention on Narcotic Drugs, reinforcing international commitments to prohibit cannabis.

1970s: Misuse of Drugs Act and Escalating Enforcement

The 1970s marked a turning point in the UK’s legal approach to cannabis. The Misuse of Drugs Act 1971 classified cannabis as a Class B drug, criminalising its possession, cultivation, and distribution. This law formed the backbone of UK drug policy for decades.

Despite this, public interest in cannabis continued to grow. Advocacy groups began calling for decriminalisation, arguing that the plant’s risks were overstated. Meanwhile, global events like the US War on Drugs influenced UK policy, leading to harsher enforcement and increased penalties for cannabis-related offences.

The infamous Operation Julie commenced in 1973 showcased the government’s determination to crack down on drug use. This operation dismantled a major cannabis and LSD smuggling network, resulting in high-profile arrests and reinforcing the stigma surrounding cannabis.

1980s: Heightened Prohibition During the “War on Drugs”

The 1980s were defined by the global escalation of the War on Drugs. In the UK, this translated to increased funding for drug enforcement and stricter penalties for cannabis offences. The Controlled Drugs (Penalties) Regulations 1985 imposed harsher sentences for possession and distribution, aligning with international trends.

Despite these measures, the 1980s also saw significant scientific advancements. Researchers discovered the endocannabinoid system, explaining how cannabis interacts with the body to produce its effects. This discovery provided a biological basis for cannabis’s medicinal potential, though it had little immediate impact on policy.

Cannabis advocacy remained marginal during this period, as public opinion was heavily influenced by anti-drug campaigns. However, small groups of activists continued to push for reform, laying the groundwork for future movements.

1990s: Early Medical Cannabis Trials and Growing Advocacy

The 1990s marked the beginning of significant changes in cannabis policy worldwide. In 1996, California legalised medical cannabis, inspiring reform movements globally. In the UK, advocacy for medical cannabis gained momentum, supported by emerging research on its potential to treat conditions like chronic pain and epilepsy.

In 1998, the UK-based company GW Pharmaceuticals was founded. The company began developing cannabis-based medicines, including Sativex, which would later be approved for treating multiple sclerosis. These developments marked the UK’s first formal steps towards recognising the therapeutic value of cannabis.

Public opinion began to shift during this decade, with increasing awareness of the plant’s medical applications. However, cannabis remained firmly classified as a controlled substance under the Misuse of Drugs Act, and recreational use continued to be criminalised.

2000s: Cannabis Policy Shifts and Medical Recognition

The early 2000s saw the UK government tentatively reconsidering its stance on cannabis. In 2004, cannabis was downgraded to a Class C drug, reducing penalties for possession. This move reflected growing recognition that cannabis posed less risk than other Class B drugs, such as amphetamines. However, this reclassification was reversed in 2009 amid political pressure and concerns about the rise of high-potency strains like “skunk.”

The 2000s also saw progress in medical cannabis. In 2001, the UK began clinical trials for Sativex, marking a major step in legitimising cannabis-based medicine. By the end of the decade, Sativex was approved for treating multiple sclerosis, though access remained limited.

Advocacy for decriminalisation and medical access continued to grow, driven by organisations like Release and Transform. These groups argued for a more evidence-based approach to drug policy, challenging the government’s punitive stance.

2010s: The CBD Boom and Medical Legalisation

The 2010s were transformative for cannabis in the UK. The wellness industry embraced CBD, a non-psychoactive compound in cannabis, which became widely available in shops and online. CBD’s popularity highlighted the potential for cannabis-derived products beyond recreational use, spurring regulatory discussions.

In 2018, the UK legalised medical cannabis following high-profile cases like those of Billy Caldwell and Alfie Dingley, two children with severe epilepsy who benefited from cannabis-based treatments. This decision marked a historic shift, though access to medical cannabis remained tightly controlled and expensive.

The UK CBD market continued to grow, with the Food Standards Agency (FSA) introducing the Novel Foods process to regulate products. This decade also saw increasing calls to reform industrial hemp laws, particularly regarding the low THC limit of 0.2%, which hindered the industry’s competitiveness.

2020s: Advocacy, Regulation, and Industry Growth

The 2020s have been defined by rapid industry growth and increasing advocacy for comprehensive cannabis reform. The COVID-19 pandemic highlighted the importance of wellness products, boosting CBD sales and renewing calls for economic recovery strategies that included cannabis industry development.

The UK clarified its 1mg THC per product rule for CBD in 2023, providing a clearer regulatory framework for businesses. At the same time, advocacy for industrial hemp reform intensified, with farmers pushing for higher THC thresholds to align with international standards.

Efforts to reform the Proceeds of Crime Act (PoCA) gained traction, as legal cannabis businesses faced challenges in securing banking and financial services.

Conclusion

The past century has seen cannabis journey from a widely used medicine and industrial crop to a heavily regulated substance and, more recently, a product of renewed interest. Each decade has brought unique challenges and opportunities, shaping public perception, scientific understanding, and legal frameworks. As the UK enters 2025, the cannabis industry continues to push for reform, advocating for a regulated market that balances public health, economic opportunity, and individual freedom. With growing public support and scientific evidence, the next decade could see cannabis fully integrated into the UK’s legal and economic landscape.

Published 11th March 2025