When, How and Why did Cannabis become illegal? - American Propaganda

Recently the USA and other countries have changed their legislation regarding the legality of cannabis. As our society begins to change its opinion on cannabis, many people wonder why the herb became illegal in the first place.

There are many theories about the different factors that pushed the United States government to impose prohibition. If you are crazy about conspiracy theories, I invite you to type in Google "why weed is illegal" you will have something to keep you busy for at least a few days.

Today we learn:

  1. When did cannabis become illegal?

  2. Why did it get criminalized?

  3. The effect on Mexicans

  4. Prohibition around the world


Limitations to the use of medicinal, recreational, or industrial cannabis occurred in most American states around 1906.

Before that cannabis was used for the production of medicinal tinctures or even the industry for the manufacture of fibers for example.

Recreational use was already quite popular around 1850, where there were hash bars in the Middle Eastern style in most major American cities.

The biggest limitation on cannabis came through poison laws like the "Pure Food Drug Act" passed by Congress in 1906. This law required that certain drugs including cannabis be properly labeled.

From there, states started to pass their own regulations on the labeling of such substances such as cannabis.

Other regulations appeared to legislate on the sale of cannabis and its derivatives in Massachusetts in 1911, and in New York and Maine in 1914.

In 1925, the United States defended the regulation of Indian hemp (main cannabis containing THC) to the International Opium Convention. This convention limited the export of Indian hemp and its by-products (such as hashish) to countries that had already banned this substance.

Around 1930, the United States created the Federal Bureau of Narcotics to ban and control recreational drugs. The agency was headed by Harry J. Anslinger who, as we will see is often seen as the father of cannabis prohibition in the USA.

In 1932, the USA passed the "Uniform State Narcotic Act" which basically asked all American states to unite against the fight against drug trafficking and manage this traffic under common laws.

By the mid-1930s, all American states had enforced cannabis laws.

The possession or transmission of Cannabis for recreational use became officially illegal across the USA by federal law of 1937 "Marijuana Tax Act".

In 1970, the "Tax Act" was replaced by the "Controlled substances Act", which listed 5 different levels of substances, with level 1 as the most dangerous and the most addictive. Cannabis was listed at the first level.

The first level substances were described as having a very high addictive power, without medicinal properties, and very dangerous.


This is where the theories get very interesting and complex. Harry J. Anslinger, the head of the agency against narcotics, is often mentioned as one of the key men in the United States for the prohibition of cannabis.

Anslinger kept his post as commissioner general of the agency for 32 years (until 1962) and also represented the USA for two years on the commission on narcotics at the United Nations. Before his post at the agency against narcotics, he worked at the head of the "Department of prohibition" in Washington DC.

According to Johan Hari, author of the book "Chasing the Scream: The First and Last Days of the War on Drugs", Anslinger began to focus on cannabis after the prohibition on alcohol ended in 1933. Until then, Anslinger apparently said that he didn't see any problems with cannabis, mainly because it didn't hurt anyone and didn't make people violent.

However, Anslinger quickly changed his mind, noting (according to Hari) that he was the head of a huge agency and had nothing to do with it. So Anslinger began to warn people of the dangerousness of the effects of cannabis; first, you enter into a delirium of rage then suffer from erotic dreams and hallucinations, before arriving at the point of no return: dementia. He was well known for his ridiculous and racist outings about cannabis and its users.

Anslinger went so far as to demonstrate the power of "devil’s weed" with the case of Victor Licata, a boy who decimated his family with an ax.

This case, coupled with a doctor's claims that cannabis was dangerous (of the 30 doctors Anslinger contacted, 29 reportedly answered no) continued to ignite Anslinger's theses in the hearts of all Americans about the powers of "Devil's grass".

In 1936, the agency noticed an increase in the consumption of cannabis. This increase continued in 1937. At this point, Anslinger launched a campaign against cannabis ( Reefer madness! ), Taking advantage of media magnate William Randolph Hearst and his journal to demonize cannabis.

By 1937, cannabis had officially become an illegal substance across the United States through the Marijuana Tax Act.


In an article published on drug policy, Dr. Malik Burnett and Amanda Reiman developed interesting arguments on how Mexican immigration influenced the movement towards criminalization of cannabis in the early 1900s.

We will not explore in detail the arguments of Burnett and Reiman, we will just summarize their point because it seems interesting to us.

The Mexican revolution was a violent struggle and took place roughly between 1910 and 1920 and radically changed the Mexican culture and its government. The revolution engendered a massive exodus to the USA, especially to states like Texas and Louisiana, which brought with them new traditions and cultures.

One such tradition was the use of cannabis, which the Mexicans called "marihuana". As the media began to demonize Mexican immigrants (as happens in most countries during an influx of foreigners), the fact that Americans did not know what "marihuana" was was very practical.

Basically, Burnett and Reiman demonstrate that demonization was an extension of the demonization of Mexicans who arrived in the USA escaping the problems in their own country.

This strategy was nothing new; the same thing appeared in the USA, Australia, and many other countries when Chinese immigration arrived. The only difference was that the Chinese were demonized for bringing opium instead of cannabis.


Cannabis laws vary from country to country. However, cannabis became illegal in most countries in 1925 after the International Opium Convention, a follow-up to the first convention signed in 1912 at La Hague in the Netherlands.

The 1912 convention was essentially the first international treaty and was particularly concerned with the development of the opium trade. It was signed by Germany, the USA, China, France, the United Kingdom, Italy, Japan, the Netherlands, Persia, Portugal, Russia, and the Kingdom of Siam.

A revised international opium convention was held in 1925 in Geneva, Switzerland. To this convention, Egypt, China, and the USA asked for a ban on hashish should be added in the texts of the treaty, previously concerned with cocaine and opium.

A subcommittee asked for the text to be enlarged to ban the production, sale, and trade of hashish and other cannabis products and limiting the use of Indian hemp for scientific and medical purposes.

India and a few other countries protested this, arguing that certain social and religious traditions, as well as the prevalence of wild cannabis, would undermine the application of these restrictions.

Consequently, this text was not incorporated into the final treaty. However, the export of Indian hemp was banned in all countries where it was illegal.

Any country wishing to import Indian hemp had to prove that its use was for medical or scientific purposes only.

In the meantime, all countries were supposed to do everything they could to stop the international trade in Indian hemp and products like hashish.

In 1961, the convention was replaced by the “Single Convention on Narcotic Drugs” to become the first international treaty to ban cannabis.

Held and signed in New York, this treaty broadened the effects of previous treaties in order to limit new opiates and broaden the framework on cannabis.

The convention gave the narcotics commission and the World Health Organization the power to add, remove, or transfer drugs listed within the four tiers established by the treaty.

In the meantime, the international narcotics control board was responsible for enforcing controls against drug production, international trafficking, exemptions, and the United Nations Office on Drugs and Crime (UNODC) had as a task to focus on specific countries and their authorities to ensure compliance with conventions.


So there you have it, a detailed analysis of when, how, and why cannabis became illegal in the US and around the world.

As told earlier, there are many alternative theories about the reasons for prohibition in the meanders of the internet. If you're interested, we think a good old Google search will find the most popular for you.

In this post, we have tried to provide you with a basic history of the events that led to decriminalization. While cannabis is still a narcotic substance for the American federal state, we believe that it will not remain so for a long time.

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