Weed was made illegal through a combination of international drug-control agreements, political decisions, public-health concerns, racial and anti-immigrant prejudice in some countries, sensational media coverage and changing attitudes towards recreational drug use.
There was no single worldwide decision that suddenly made cannabis illegal. Different countries introduced controls at different times and for different reasons.
In Britain, international drug-control agreements played an important role in cannabis restrictions introduced in the 1920s.
In the United States, prohibition developed through state laws, political campaigns and federal restrictions.
Cannabis laws have continued to change since then. Medical cannabis became legally available under strict conditions in the UK in 2018, while recreational cannabis remains illegal in 2026.
Modern statistics also show an important distinction between cannabis prohibition and cannabis use.
Cannabis remains the most commonly used illegal drug in England and Wales, although official figures do not show that its use is simply increasing every year.
Why Was Weed Made Illegal in the First Place?
Cannabis became illegal gradually rather than because scientists discovered one particular danger that immediately convinced governments to ban it.
During the 19th century, cannabis was used medically in Britain and other countries. Hemp varieties of the cannabis plant were also grown for practical purposes such as fibre and rope.
Attitudes began changing during the early 20th century as governments developed international systems for controlling psychoactive substances.
Several influences contributed to cannabis prohibition:
- International Drug Agreements: Governments increasingly cooperated to restrict substances considered capable of causing intoxication or dependence.
- Public-Health Concerns: Officials worried about the possible physical, psychological and social consequences of recreational drug use, much as modern health guidance distinguishes between substances and their particular risks, including the reasons behind avoiding alcohol with certain antibiotics.
- Political Pressure: International agreements encouraged participating countries to introduce compatible domestic laws.
- Racial And Anti-Immigrant Prejudice: Particularly in the United States, cannabis became associated with Mexican immigrants and other minority communities.
- Media Campaigns: Sensational stories sometimes connected cannabis with violence, insanity and crime without strong supporting evidence.
- Changing Medical Practice: Cannabis became less important in mainstream Western medicine as pharmaceutical treatments became more standardised.
- Social Attitudes: Recreational intoxication increasingly became treated as an issue requiring government control.
These influences differed between countries, which is why the history of British cannabis prohibition cannot simply be explained by events in the United States.
Why Did Britain Make Cannabis Illegal in 1928?
Cannabis was brought under stricter British drug controls in 1928 following international efforts to regulate the substance.
Britain already had the Dangerous Drugs Act 1920, but cannabis was not originally the central target of that legislation. Early British drug controls were primarily concerned with substances including opium and cocaine.
International negotiations during the 1920s changed the position.
Cannabis was eventually added to Britain’s controlled-drug framework following commitments associated with international drug-control agreements. This is important because Britain was not responding to evidence of a huge domestic cannabis epidemic.
Cannabis use existed, but recreational cannabis was relatively uncommon in Britain compared with the visibility it gained several decades later.
The UK’s original cannabis restrictions therefore need to be understood in the context of international drug policy as well as domestic concerns about intoxicating substances.
What Role Did the 1925 International Opium Convention Play?
The International Opium Convention agreed in Geneva in 1925 became an important turning point in international cannabis regulation.
Egypt was among the countries pushing strongly for cannabis controls. Egyptian representatives argued that cannabis presented serious social and health problems and wanted international restrictions placed on its movement.
Cannabis was consequently incorporated into the developing international drug-control system.
Britain later implemented measures connected with those obligations, bringing cannabis under the Dangerous Drugs Act framework in 1928.
This means Britain’s cannabis prohibition was not simply copied from America’s later policies. UK restrictions appeared before the famous American Marihuana Tax Act of 1937.
International diplomacy therefore played a major role in explaining why cannabis became controlled in Britain.
Why Did the United States Make Marijuana Illegal?
The American story developed differently.
Cannabis medicines had previously been available in the United States, but attitudes changed during the early 20th century.
Cannabis use became increasingly associated in political and media reporting with Mexican immigrants following substantial Mexican migration into the United States.
Several American states began restricting cannabis before the federal government introduced nationwide controls.
Concern about drugs was mixed with wider fears about immigration, crime and changing social behaviour.
By the 1930s, federal officials were campaigning aggressively against marijuana, portraying it as a substance capable of causing violence, irrational behaviour and moral decline.
Those claims helped build public support for stricter controls.
How Did Racism, Immigration And Media Campaigns Influence Cannabis Laws?
Racial prejudice was an important element of early American cannabis politics.
Cannabis became strongly associated with Mexican immigrants, while its use was also linked in public discussion with Black jazz musicians and other minority communities.
Some newspapers and politicians promoted stories portraying marijuana users as dangerous or uncontrollable.
The term “marijuana” itself became increasingly prominent during this period, helping distinguish the feared recreational drug presented in political campaigns from the cannabis preparations that had previously appeared in medicines.
Popular culture reinforced these fears.
The 1936 film Reefer Madness, for example, portrayed cannabis as capable of driving users towards violence, mental breakdown and reckless behaviour.
Modern historical accounts generally regard many of these representations as exaggerated.
However, at the time they contributed to the political environment supporting cannabis prohibition.
Who Was Harry Anslinger And What Role Did He Play?
Harry Anslinger became one of the most influential figures in the history of American marijuana prohibition.
He served as commissioner of the Federal Bureau of Narcotics from 1930 and became a prominent campaigner against cannabis.
Anslinger promoted stories connecting marijuana with criminal behaviour, violence and social decline. Some of the rhetoric used during anti-cannabis campaigns also reflected the racial prejudices of the period.
His agency collected dramatic reports of crimes supposedly linked to marijuana and used them to support arguments for federal intervention.
The resulting campaign helped build political support for the Marihuana Tax Act of 1937.
Anslinger therefore did not single-handedly make marijuana illegal, but he played an important role in shaping American public opinion and federal cannabis policy.
What Did the Marihuana Tax Act of 1937 Do?
The Marihuana Tax Act of 1937 became a major milestone in US cannabis prohibition.
It did not simply declare cannabis illegal in the same way that later controlled-drug legislation would.
Instead, the law imposed strict taxation, registration and administrative requirements on people handling marijuana.
Failure to comply could result in criminal penalties, making lawful cannabis activity extremely difficult.
The Act significantly restricted medical and recreational cannabis at federal level and became the foundation for decades of stronger prohibition.
Its legal structure eventually faced a major challenge.
In 1969, the US Supreme Court ruled in Leary v. United States that important aspects of the Marihuana Tax Act conflicted with constitutional protections against self-incrimination.
The federal government subsequently replaced the system with the Controlled Substances Act of 1970.
Cannabis was placed in Schedule I under that legislation, producing the modern federal prohibition framework.
What Did the Wootton Report And Shafer Commission Say About Cannabis?
Government reviews in both Britain and the United States later questioned whether existing attitudes towards cannabis accurately reflected its risks.
In Britain, the Wootton Report was published in 1968.
The committee found that the dangers associated with cannabis had often been overstated. It did not conclude that cannabis was harmless, nor did it recommend completely unrestricted availability.
Instead, its findings suggested that the social consequences of cannabis use did not justify some of the extreme claims previously made about the drug.
A similar debate occurred in the United States.
The National Commission on Marihuana and Drug Abuse, commonly known as the Shafer Commission, published its findings in 1972.
It recommended moving away from criminal penalties for possession of small amounts of marijuana for personal use.
President Richard Nixon’s administration did not adopt the commission’s central recommendation, and federal prohibition continued.
These reports are important because they demonstrate that governments were receiving more nuanced scientific advice even while strict cannabis laws remained in place.
How Did UK Cannabis Laws Change From 1971 To 2009?
The Misuse of Drugs Act 1971 created the modern framework for controlling drugs in the UK.
Cannabis was placed in Class B when the system was introduced.
It is sometimes said that cannabis was first banned in Britain in 1971, but this is misleading. Cannabis had already been controlled decades earlier.
The 1971 Act reorganised and modernised the UK’s controlled-drug system rather than introducing Britain’s first cannabis prohibition.
Cannabis classification later changed several times.
In January 2004, cannabis was moved from Class B to Class C following government consideration of its relative harms.
The change reduced the maximum penalty attached to possession but did not legalise cannabis.
Concerns subsequently increased about stronger varieties of cannabis and possible mental-health risks.
The government decided to return cannabis to Class B, with the reclassification taking effect in 2009.
Cannabis has remained a Class B controlled drug since then.
Why Was Medical Cannabis Legalised in the UK in 2018?
An important change occurred on 1 November 2018 when certain cannabis-based products for medicinal use were moved to Schedule 2 of the Misuse of Drugs Regulations.
The change followed growing medical and public attention surrounding patients, including children with severe forms of epilepsy, who might benefit from cannabis-based medicines.
The reform created a legal route for qualifying cannabis-based medicinal products to be prescribed under tightly controlled circumstances.
It did not legalise cannabis generally.
The rules distinguish authorised medical treatment from recreational cannabis possession, production and supply.
Medical cannabis prescribing also remains much more restricted than prescriptions for many conventional medicines.
The change nevertheless represented a major shift because it formally recognised that certain cannabis-based products could have legitimate medical uses.
If Medical Cannabis Is Legal, Why Is Recreational Weed Still Illegal?
Medical cannabis and recreational cannabis are treated differently because UK law regulates substances according to their purpose, product and authorisation.
Similar distinctions between restrictions, safety guidance and outright prohibition can also be seen in questions about why Lemsip is thought to be banned, where regulatory concerns do not automatically mean a product is illegal.
Certain cannabis-based medicinal products can legally be prescribed under controlled circumstances.
That does not give someone general permission to possess ordinary cannabis.
Recreational cannabis remains a Class B controlled drug because the government continues to consider its health, social and criminal-market risks sufficient to justify prohibition.
The distinction works broadly like this:
- Medical Cannabis: Certain qualifying products can be legally prescribed within the regulated medical system.
- Recreational Cannabis: Unauthorised possession remains illegal.
- Cannabis Cultivation: Growing cannabis generally requires legal authority or licensing.
- Cannabis Supply: Unauthorised selling or supplying remains a criminal offence.
Legal medical use therefore represents a limited exemption within a wider system of cannabis control rather than full legalisation.
Is Weed Use Increasing in the UK?
Official statistics do not show cannabis use simply increasing every year.
The latest Office for National Statistics data available in 2026 covers the year ending March 2025 for England and Wales.
Cannabis remained the most commonly used illegal drug.
Around 6.5% of people aged 16 to 59 reported using cannabis during the previous 12 months.
Among people aged 16 to 24, the rate was higher at 12.5%.
However, neither figure represented a statistically significant increase compared with the year ending March 2024.
The longer-term picture among younger adults actually shows a decline.
Cannabis use among people aged 16 to 24 was 16.4% in the year ending March 2015, compared with 12.5% in the year ending March 2025.
So it would be inaccurate to say that cannabis use is consistently rising year after year.
What Does Official ONS Data Show About Cannabis Use?
The Crime Survey for England and Wales provides one of the most important official measures of illegal drug use.
For the year ending March 2025, the Office for National Statistics reported:
| Measure | Official Figure |
| Cannabis Use Among People Aged 16 To 59 | 6.5% |
| Cannabis Use Among People Aged 16 To 24 | 12.5% |
| Cannabis Use Among 16 To 24-Year-Olds In 2015 | 16.4% |
| Any Drug Use Among People Aged 16 To 59 | 8.7% |
| Any Drug Use Among People Aged 16 To 24 | 15.1% |
Cannabis has remained the most commonly used illegal drug covered by the survey since estimates began in the 1990s.
However, prevalence can move up or down between individual years.
Official survey figures should therefore be assessed over longer periods rather than assuming that one year’s movement represents a permanent trend.
Is Cannabis Use Increasing Among Young People?
The latest figures do not indicate a long-term increase among people aged 16 to 24.
In the year ending March 2025, 12.5% of people in this age group reported cannabis use during the previous year.
That was not significantly different from the previous year’s figure.
More importantly, it was below the 16.4% recorded in the year ending March 2015.
The wider ONS data on illegal drug use also show a substantial long-term decline among young adults compared with levels recorded during the late 1990s.
This means claims that cannabis use among young people is continually increasing should be treated cautiously.
How Often Do Cannabis Users Take It?
Looking only at how many people have used cannabis at least once during a year can hide substantial differences in frequency.
Official ONS figures for the year ending March 2025 found that 36.5% of cannabis users aged 16 to 59 had used cannabis more than once a month.
Around 10.4% of cannabis users reported using it every day.
The proportion using cannabis more than once a month was similar to the previous year’s estimate of 34.0%.
This distinction matters because someone who reports cannabis use once or twice during a year is counted alongside someone who uses it every day when annual prevalence is measured.
Frequency data therefore provide additional context about patterns of consumption.
They should not, however, automatically be interpreted as evidence of dependence. Frequency of use and clinical drug dependence are different measures.
Are Cannabis Seizures Increasing In England And Wales?
While population surveys do not show cannabis use increasing consistently, cannabis seizures rose substantially in the latest official Home Office figures.
During the year ending March 2025, police forces and Border Force recorded 194,682 cannabis seizures.
That was a 28% increase from 152,660 seizures during the previous year.
Cannabis accounted for more than 94% of Class B drug seizures.
Herbal cannabis seizures increased from 134,570 to 173,215, while cannabis resin seizures increased from 10,959 to 14,448.
The quantity of herbal cannabis seized also increased substantially.
Authorities seized approximately 137.21 tonnes of herbal cannabis, compared with 85.01 tonnes the previous year.
Much of the increase was driven by Border Force activity and several large seizures.
This does not mean cannabis use increased by the same amount.
The Home Office specifically warns that seizure statistics can be affected by enforcement activity, Border Force operations, recording practices and changes in drug markets.
A rise in cannabis seizures therefore shows increased interception of cannabis, not necessarily an equivalent rise in the number of people using it.
Is Weed Still Illegal In The UK In 2026?
Yes. Recreational cannabis remains illegal in the UK in 2026.
Cannabis continues to be controlled as a Class B drug under the Misuse of Drugs Act 1971.
Unauthorised possession can result in serious legal consequences. Supply, production and cultivation can carry substantially greater penalties.
The maximum penalty for Class B possession can reach five years’ imprisonment, while supply or production offences can carry a maximum sentence of 14 years’ imprisonment.
Certain cannabis-based medicinal products remain legally available under the regulated medical system.
This means the UK’s position in 2026 is not complete cannabis prohibition in every circumstance, but neither is it general legalisation.
Understanding that distinction is important because something facing regulatory controls is not necessarily completely prohibited, a distinction that also appears in discussions about whether basa fish is banned in the UK.
The law continues to distinguish tightly controlled medical use from unauthorised recreational possession, cultivation and supply.
Conclusion
Weed was not made illegal because of one event or one scientific discovery.
Cannabis prohibition developed through a mixture of international drug-control agreements, political decisions, health concerns, social attitudes and, particularly in the United States, racialised and anti-immigrant campaigns.
Britain brought cannabis under drug-control legislation in 1928 following developments in international drug policy.
The United States followed a different route involving state restrictions, Harry Anslinger’s federal campaign, the Marihuana Tax Act of 1937 and eventually the Controlled Substances Act of 1970.
Scientific and government attitudes became more nuanced over time.
Reports such as the Wootton Report and Shafer Commission questioned some of the earlier assumptions surrounding cannabis, while medical cannabis reforms eventually recognised legitimate therapeutic applications.
Despite those changes, recreational cannabis remains illegal in the UK in 2026.
Cannabis also remains the most commonly used illegal drug in England and Wales, although official statistics do not support the idea that use is rising every year.
The latest ONS figures show relatively stable recent prevalence and lower cannabis use among young adults than a decade earlier, even as official cannabis seizures have increased sharply.
Frequently Asked Questions
Why Was Weed Originally Made Illegal?
Weed became illegal because of a combination of international drug-control agreements, political pressure, health concerns, changing social attitudes and, particularly in the United States, racialised and anti-immigrant campaigns.
When Did Weed Become Illegal In The UK?
Cannabis was brought under British drug controls in 1928 following international developments associated with the 1925 International Opium Convention.
Why Was Marijuana Made Illegal In The United States?
American prohibition developed through state restrictions, anti-drug campaigns, racial and immigration politics and federal action culminating in the Marihuana Tax Act of 1937 and later the Controlled Substances Act of 1970.
Was Weed Banned Because It Was Considered Dangerous?
Concerns about health and behaviour contributed to prohibition, but they were not the only reasons. Politics, international agreements, social attitudes and prejudice also influenced cannabis laws.
Is Cannabis Use Increasing In The UK?
Not consistently. ONS figures for the year ending March 2025 showed no statistically significant annual increase in cannabis use among either 16 to 59-year-olds or 16 to 24-year-olds.
How Many People Use Cannabis In England And Wales?
The latest official prevalence data show that 6.5% of people aged 16 to 59 and 12.5% of those aged 16 to 24 reported cannabis use during the previous 12 months in the year ending March 2025.
Is Cannabis Still A Class B Drug In The UK In 2026?
Yes. Cannabis remains a Class B controlled drug in the UK in 2026, although certain cannabis-based medicinal products can legally be prescribed under regulated circumstances.
