Wednesday, 5 August 2026

Medical Cannabis in the UK: Legalisation, Unequal Access and Human Rights, an article by Lydia Kitchen

 

Medical Cannabis in the UK: Legalisation, Unequal Access and Human Rights

Lydia Kitchen

Drug Science

Wednesday 05 Aug 2026

Lydia Kitchen is a PhD candidate in Law at the University of Leicester. Her research examines human rights, healthcare decision-making and structural inequality, with a particular interest in drug policy and access to treatment.

Since 2018, cannabis-based products for medicinal use have been available on prescription in the UK. However, NHS access remains exceptionally limited. NHS figures reported to Parliament show that fewer than five patients have received prescriptions for unlicensed products, while more than 1.4 million people are estimated to use cannabis for medical purposes. Private clinics are the main lawful route outside the NHS, but many cannot afford the ongoing costs. People outside the prescription system may still rely on cannabis to manage their health and risk criminalisation.

My recent article in Amicus Curiae, Barriers to Medical Cannabis in the UK: Human Rights Implications of Criminalization and Inequitable Access, examines the gap between legal recognition and practical access from a human rights perspective. It considers whether criminalisation can be justified when people use cannabis therapeutically but cannot obtain a prescription. The central issue is who the system protects and who it leaves exposed to criminalisation. Income, disability and gender can shape access to a prescription, while racial inequalities in drug law enforcement affect who bears the consequences of remaining outside it. A legal distinction shaped by these inequalities becomes increasingly difficult to justify.


Legalisation Without Meaningful Access

In 2018, the law changed to allow specialist doctors to prescribe cannabis-based products for medicinal use. This created a lawful route to treatment, although access remains tightly restricted. A small number of licensed cannabis-based medicines are available through the NHS for certain forms of severe epilepsy, chemotherapy-induced nausea and vomiting, and spasticity caused by multiple sclerosis. Private treatment largely involves unlicensed products, including cannabis flower and oils, which are closer to the forms commonly used outside the prescription system. They can be prescribed lawfully, but NHS access is almost non-existent because NICE guidance shapes NHS prescribing and does not recommend them for routine use.

NICE follows established evidence standards that place substantial weight on randomised controlled trials. These remain important, but cannabis can be difficult to assess through this model. Unlike single-compound medicines, cannabis-based products contain varying combinations of active compounds and may affect patients differently, while psychoactive effects can reveal whether participants received the active treatment. Real-world evidence can therefore complement clinical trials. Drug Science’s Project Twenty21 collected longitudinal data from more than 4,500 patients prescribed cannabis for a range of conditions, yet evidence of this kind still carries less weight in NICE guidance.

A 2019 NHS England review identified gaps in specialist education, governance processes, funding and supply as barriers to NHS prescribing. Private clinics remain the main lawful route to unlicensed products, but access requires specialist assessment, medical records, a diagnosis and evidence that conventional treatments have been tried. This can be especially restrictive for conditions such as endometriosis, which takes an average of nine years and four months to diagnose in the UK. Patients may therefore manage symptoms for years before meeting these requirements.

For those who qualify and can sustain the costs, a prescription provides lawful access and protection from possession offences. Without one, possession remains an offence under the Misuse of Drugs Act 1971. Therapeutic use alone is not a defence, so two people may use cannabis for similar health reasons while only the prescribed patient is protected from criminal sanction.


How Limited Access Deepens Inequality

Limited access does not affect everyone in the same way. Private prescriptions can cost hundreds of pounds each month once medication, consultations and clinic charges are included. For people whose health affects their ability to work or creates additional costs, private treatment may be particularly difficult to sustain. Those needing ongoing treatment may therefore be among the least able to pay for lawful access.

Outside the prescription system, criminalisation compounds that disadvantage. A conviction can affect employment, housing and social inclusion. There is also the immediate stress of relying on something illegal to manage a health condition. Patients prescribed cannabis have reported that, despite legal protection, prohibition still produces stigma and anxiety around using medication in public.

These harms are not distributed equally. Research in England and Wales has consistently documented that Black people are disproportionately stopped and searched, prosecuted and convicted for drug offences, including cannabis possession. The ability to pay privately therefore shapes access to legal protection within an already unequal enforcement system.

People with disabilities and chronic illnesses may face lower incomes and additional costs. Those growing cannabis for medical reasons have described how failures in conventional care, criminalisation and reliance on illicit markets can overlap. Women face related barriers because endometriosis and fibromyalgia disproportionately affect them, while diagnosis can take years and effective treatments remain limited. If lawful access depends on diagnosis and previous treatment, existing healthcare inequalities can influence who receives legal protection.

Intersectionality helps explain how income, race, gender and disability can interact so that one person faces several barriers at once, affecting both access to a prescription and exposure to criminalisation. Equality cannot be understood simply as applying the same criminal law to everyone. A rule may appear neutral while placing a heavier burden on groups already disadvantaged. Where lawful protection is unequally accessible, treating everyone outside the prescription system in the same way can reinforce those inequalities.


Autonomy, Equality and Criminalisation

Restricted access and continued criminalisation raise questions about autonomy and equality under the European Convention on Human Rights. Although the Convention does not create a specific right to medical cannabis or guarantee access to a chosen treatment, the current framework must still comply with the rights it protects.

Article 8 protects private life, including personal autonomy, self-determination and bodily integrity. Criminal law is a serious form of state interference in decisions about managing a health condition. The risk of arrest or prosecution can affect how cannabis is obtained and used, discourage disclosure to healthcare professionals and add to the anxiety of managing a condition outside the law. However, Article 8 is not absolute. Governments may interfere with private life to protect public health, but any interference must be lawful, necessary and proportionate. The 2018 reforms make blanket criminalisation harder to justify because the law now recognises cannabis as a legitimate medical treatment. Someone outside the prescription system can still be criminalised without considering why they use cannabis or why a prescription was unavailable. Concerns about unregulated cannabis remain relevant, but they must be weighed against the harms of criminalisation and less restrictive alternatives.

Article 14 prohibits discrimination in the enjoyment of Convention rights, including Article 8. This includes indirect discrimination, where an apparently neutral rule has disproportionately harmful effects. A prescribed patient and someone outside the prescription system may be managing comparable health problems, yet only one is protected from criminal sanction. Access to a prescription can depend on income, diagnosis, previous treatment and the ability to navigate specialist private healthcare. These barriers interact with disability, gender and socioeconomic disadvantage, while those outside the lawful system also face racial inequalities in drug enforcement. The European Court of Human Rights gives particular weight to discrimination involving disability and health status, recognising that vulnerable groups may require stronger protection. Where access has been shaped by structural disadvantage, criminalisation cannot easily be treated as an individual choice not to comply with the law.

Governments have considerable discretion over health policy and public spending, making it difficult to argue that human rights law requires universal NHS provision. Human rights principles nevertheless strengthen the case for Parliament to reform the law. Decriminalising possession is narrower than universal NHS provision and offers the most realistic starting point for a rights-based approach.


Formal Decriminalisation and Wider Reform

Here, decriminalisation means removing possession for personal use from criminal law. It would not create a commercial market or remove controls on production and supply. Some police forces already use diversion schemes and other out-of-court responses for low-level possession. These may prevent prosecution, but the offence remains. Protection therefore depends on local practice and police discretion, creating inconsistency and legal uncertainty.

Legislative reform would provide clearer and more consistent protection. Stevens, Eastwood and Douse propose repealing sections 5(1) and 5(2) of the Misuse of Drugs Act 1971. The London Drugs Commission has recommended removing cannabis from that Act so possession would instead fall under the Psychoactive Substances Act 2016, where it is generally not an offence outside custodial settings.

A narrow medical exemption would risk reproducing barriers already present in the prescription system. People may use cannabis for several reasons or recognise its therapeutic value before receiving a formal diagnosis, so medical and recreational use do not always divide neatly. Requiring proof of medical need would disadvantage those whose conditions are difficult to diagnose or whose symptoms have not been taken seriously. Decriminalising possession would avoid making legal protection depend again on medical documentation and healthcare access.

Reform must also address how personal possession is distinguished from supply. Someone using cannabis regularly for a chronic condition may keep a larger quantity to reduce costs, maintain a reliable supply or limit contact with the illicit market. Fixed quantity thresholds could expose therapeutic users to supply allegations even where the cannabis is intended for personal use.

International experience highlights the importance of health and social support alongside legal reform. Portugal, for example, removed criminal penalties for possession of small quantities of drugs for personal use in 2001, alongside investment in treatment, harm reduction and prevention. In the UK, decriminalisation would not expand NHS prescribing or make private treatment affordable. Wider NHS access, better education for healthcare professionals and the police, and further research would still be needed. Reform should also consider expunging previous cannabis possession convictions to address past harms. Decriminalisation would nevertheless be an important first step, preventing people excluded from lawful medical access from also being criminally punished.


Beyond the 2018 Reforms

The 2018 reforms recognised cannabis as a legitimate medical treatment, but legal protection is limited to those able to obtain a prescription. People using cannabis for similar health reasons can therefore face starkly different legal consequences when cost, delayed diagnosis or other healthcare barriers prevent access. The central problem is the relationship between restricted access and continued criminalisation. Decisions about managing illness engage autonomy, while unequal access and enforcement place a heavier burden on those already disadvantaged. Where people unable to obtain lawful treatment remain exposed to criminal sanction, the current framework does not provide equal protection in any meaningful sense.

Decriminalising possession for personal use would remove one of the clearest harms of the current system. Wider reform is still needed to improve NHS access and affordability, support further research and build public and professional understanding. The 2018 reforms should be judged by the protection they provide in practice. Access and criminal justice policy must be addressed together so that people are not punished because lawful treatment was beyond their reach.


Saturday, 1 August 2026

Cannabis Did Not Always Produce THC and This Study Shows How Evolution Figured It Out

Cannabis Did Not Always Produce THC and This Study Shows How Evolution Figured It Out

Tibi Puiu

ZME Science

Friday 31 Jul 2026

Ancient enzymes reveal how evolution shaped cannabis chemistry, and how scientists may harness it.

Cannabis did not evolve THC with a single, elegant molecular stroke.

Instead, the plant appears to have stumbled toward it by “experimenting” chemically, copying useful genes, and slowly refining a messy process into the precise cannabinoid assembly line we recognize today. According to a new study from Wageningen University & Research, the familiar compounds THC (tetrahydrocannabinol), CBD (cannabidiol), and CBC (cannabichrome) emerged from such an evolutionary period of biochemical improvisation.

By resurrecting long-extinct enzymes and testing them in the lab, researchers have reconstructed how cannabis acquired the ability to make its signature molecules (including those that can make you high). This is the first experimental evidence for how cannabinoid biosynthesis originated and diversified within the cannabis lineage.

The results also hint at something unexpected: the oldest versions of these enzymes may be better suited for modern biotechnology than their highly specialized descendants.

When Cannabis Enzymes Did Not Pick Sides

In living cannabis plants, cannabinoid production looks tidy. Different enzymes handle different jobs. One mostly produces the precursor to THC. Another focuses on CBD. A third leads to CBC.

But evolution rarely starts with tidy systems.

The Wageningen team shows that the earliest cannabis-specific enzyme involved in cannabinoid biosynthesis was a generalist. Rather than making a single product, it converted the same starting molecule into several different cannabinoid acids at once.

That starting molecule, known as CBGA, is sometimes called the “mother cannabinoid.” Modern enzymes push it down narrow chemical paths. The ancestral enzyme did not. It generated a mixture: THCA, CBDA, and CBCA together.

Rebuilding Enzymes from Deep Time

To uncover this history, the researchers used ancestral sequence reconstruction, a technique that allows scientists to infer ancient proteins from modern DNA.

They compared cannabinoid-related genes from cannabis with those from close relatives such as hops. Using evolutionary models, they predicted what key enzymes must have looked like millions of years ago. Then they synthesized those genes and expressed them in yeast, effectively bringing ancient plant enzymes back to life.

This approach let them test not just what the genes looked like, but what they actually did.

The results revealed a clear sequence. Enzymes predating cannabis showed no ability to process CBGA. The first enzyme unique to cannabis could process it, but did so broadly, producing multiple cannabinoids. Only after later gene duplications did enzymes emerge that strongly favored THC or CBD pathways.

This pattern — generalists first, specialists later — is common in evolution. It gives organisms room to explore chemical possibilities before natural selection locks in the most useful ones.

Copying Genes, Inventing Chemistry

Gene duplication seems to have been key in the cannabis plant’s journey towards molecular specialization.

When a gene duplicates, one copy can maintain its original function. The other gains freedom to mutate. Sometimes that freedom leads nowhere. Sometimes it leads to entirely new chemistry.

Cannabis appears to have used this evolutionary trick repeatedly. Duplications of a single ancestral enzyme allowed different copies to drift toward different cannabinoid products. Over time, those copies became increasingly specialized.

This challenges earlier assumptions that CBD-like compounds came first. Instead, the ancestral enzyme already produced THC precursors alongside others, suggesting that psychoactive chemistry emerged early — and only later became finely tuned.

For the plant, these compounds were unlikely to matter because of their effects on humans. More likely, they played roles in defense, stress response, or microbial resistance. Chemical diversity itself can be an advantage when threats are unpredictable.

Ancient Enzymes, Modern Advantages

The study’s evolutionary insights come with a practical twist.

The resurrected ancestral enzymes turned out to be easier to work with than modern ones. In yeast cells, they expressed more readily and functioned more robustly.

“What once seemed evolutionarily ‘unfinished’ turns out to be highly useful,” says Robin van Velzen in a Wageningen University & Research press release. “These ancestral enzymes are more robust and flexible than their descendants, which makes them very attractive starting points for new applications in biotechnology and pharmaceutical research.”

This matters because demand for medically relevant cannabinoids keeps rising, while plant-based production remains slow and variable. Biotechnological approaches—such as using microbes instead of crop fields—promise consistency and scale, but enzyme performance often limits progress.

Ancient enzymes may offer a shortcut.

Rethinking Rare Cannabinoids like CBC

One cannabinoid stands out in the study: CBC.

CBC has drawn scientific interest for potential anti-inflammatory and pain-related effects, yet it appears only in small amounts in most cannabis plants. According to the researchers, this scarcity stems from enzyme specialization that favored other pathways.

“At present, there is no cannabis plant with a naturally high CBC content. Introducing this enzyme into a cannabis plant could therefore lead to innovative medicinal varieties,” van Velzen says.

In the lab, the team engineered intermediate enzyme forms that produced CBC with striking specificity. That opens two possible futures: cannabis plants redesigned to favor rare cannabinoids, or microbes engineered to produce them efficiently.

What Evolution Still Keeps Hidden

Despite the clarity and elegance of the experiments, gaps remain.

The researchers note that limited genomic data from hop leaves open the question of whether early cannabinoid activity arose just before or just after cannabis split from its relatives. Evolutionary reconstructions also cannot perfectly capture the order of ancient mutations.

Still, the study marks a shift. It moves cannabinoid evolution from speculation to experimental testing.

By replaying evolution in the lab, scientists can now see how cannabis chemistry took shape. In this view, THC is not just a cultural artifact or a pharmacological tool. It is the product of evolutionary trial and error, refined over millions of years. And some of the most promising tools for tomorrow may come not from cannabis’s present, but from its deep molecular past.

The findings appeared in the Plant Biotechnology Journal.

https://www.zmescience.com/science/news-science/cannabis-evolution-of-thc/

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