A popular story says a newspaper owner, a chemical company and a banker had hemp banned in the United States in 1937. This part checks each claim in that story against the documents. Those documents include the 1937 hearings, patent records, a biography of the newspaper owner and a 1938 Popular Mechanics article. It also covers what historians see as the real causes and the government’s wartime hemp programme of 1942.
The law in question is the Marihuana Tax Act of 1937. President Franklin D. Roosevelt signed it on 2 August 1937, and it came into force on 1 October 1937. It did not ban cannabis outright. Instead, it used registration and very high taxes on anyone outside the registered system. That made legal trade close to impossible in practice.
This is United States legal history from 1937. It is not Thai law and does not apply in Thailand. The Thai rules are summarised in section 8 below.
This is Part 2. Part 1: The 1937 File: How the United States Banned Industrial Hemp — and Which Parts of the Famous Conspiracy Theory Survive Scrutiny
4. The Conspiracy Theory, Claim by Claim
The version told in cannabis writing is the Hearst–DuPont–Mellon theory. Jack Herer, an American cannabis activist, made it popular in his book The Emperor Wears No Clothes (first edition 1985).
The people in the story are:
- William Randolph Hearst, owner of a large US newspaper chain;
- DuPont, the US chemical company that developed nylon;
- Andrew Mellon, a banker who had headed the US Treasury until 1932;
- Harry J. Anslinger, head of the Federal Bureau of Narcotics (FBN), the agency that pushed for the Act.
The theory runs roughly like this:
- Hearst owned timber and newsprint businesses. Cheap hemp paper threatened them.
- DuPont had just patented nylon and needed hemp fibre out of the way.
- Mellon was DuPont’s banker and was related to Anslinger by marriage.
- A new decorticator was about to make hemp cheap to process. A decorticator is a machine that strips the fibre from the woody core of the stalk.
- Hearst’s newspapers ran a racist scare campaign, and the Act followed.
Here is how each claim compares with the documents.
| Claim | Verdict | What the documents show |
|---|---|---|
| Hearst papers ran sensational anti-marijuana stories | Supported | Even critics of the theory accept this. Much of the US press did the same. A widely quoted headline, “Murder Weed Found Up and Down Coast”, is said to date from January 1933. Nobody has traced it to a specific paper and date, so treat that wording as unconfirmed |
| The word “marihuana” hid what the plant was medically | Supported in effect | Woodward, the American Medical Association’s lawyer, told the committee the doctors learned of the bill late. One reason was the unfamiliar name (Part 1, section 3) |
| The FBN had its own reasons to want the law | Supported | The FBN was created in 1930. It faced budget cuts during the Great Depression and wanted a wider role |
| The Act ended commercial hemp growing in the US | Overstated | Hemp had been declining for a long time before 1937. The Act added a tax and paperwork burden. Production started again in wartime from 1942 (section 9) and fell again after the war |
| Hearst wanted to protect his business | Not supported | Hearst’s papers bought newsprint (the paper newspapers are printed on); they did not make it. In the 1930s they depended heavily on newsprint imported from Canada. Cheaper hemp paper would have cut Hearst’s costs, not threatened him |
| DuPont needed hemp gone to make way for nylon | Not supported | Wallace Carothers, the DuPont chemist behind nylon, filed patent applications from 1935. One example is US 2,130,523, filed on 2 January 1935. The patents were granted in 1937–38. US 2,130,523 and US 2,130,948 were both granted on 20 September 1938. No document links DuPont to drafting the Act or lobbying for it. Nylon’s first big market was stockings, where it competed mainly with silk, not hemp |
| A new decorticator was about to change hemp’s economics | Not supported as stated | George Schlichten built a machine in the 1910s. It never reached commercial-scale production before his death in 1923. The newer machines of the 1930s, described in 1938, were not commercially proven (section 5) |
| Mellon was behind it | Family link: supported. Banking motive: no evidence | Anslinger’s wife, Martha Denniston, was Mellon’s niece. No document links Mellon’s banking interests to the Act. Mellon had left the Treasury in 1932 |
| The 1938 Popular Mechanics article shows what was being lost | Not evidence of motive | The article appeared in February 1938, after the Act. Herer’s side says it was written in spring 1937, before the law passed. Even so, nothing shows that the people who wrote or backed the bill read it, feared it or acted on it (section 5) |
The pattern is consistent. The claims that hold up are about sensational press coverage, the choice of the word “marihuana” and the FBN’s own interests. The claims that fail are the ones about business motives.
When you meet one of these claims in a post or a video, find its row in this table. Then ask the person for the original document behind it, such as a newspaper with its date, a patent number or a hearing record.
5. The February 1938 Popular Mechanics Article
The article “New Billion-Dollar Crop” appeared in Popular Mechanics in February 1938. It is the document hemp campaigners cite most often. Popular Mechanics was a mass-market technology magazine, not a campaign publication. That makes the article useful evidence of how the technology press saw hemp at the time.
What the article says
- A newly available decorticator could separate the fibre from the stalk by machine. The article says this would make hemp profitable.
- The woody waste left after removing the fibre is more than 77% cellulose. Cellulose is the main material in plant cell walls and the raw material for paper.
- That cellulose could go into more than 25,000 products, “from dynamite to Cellophane”. Cellophane is a clear film made from cellulose.
- A government estimate says 10,000 acres of hemp (about 25,000 rai) would give as much paper as 40,000 acres (about 100,000 rai) of average land used for pulpwood.
- The crop could be worth several hundred million dollars a year to American farmers.
- The article also covers the drug question directly. It notes that the female flower contains a narcotic and suggests the worry about this was exaggerated.
The question of the date
The Act was signed on 2 August 1937 and came into force on 1 October 1937. The article appeared about six months later. Herer and other hemp campaigners reply that it was written in spring 1937, before the law passed, and printed late. That may be true. Even so, the article is still not evidence of a motive, for two reasons.
First, a forecast in a technology magazine does not prove that a newspaper owner, a chemical company or a lawmaker saw hemp as a threat. No document connects this article, or the machines it describes, to the people who wrote or pushed the bill.
Second, the article’s authors knew about the new regulation. The article ends with the hope that “federal regulations can be drawn to protect the public without preventing the legitimate culture of hemp”. That reads as a reaction to the new tax system, not as a warning about a hidden plot.
What the article does and does not prove
The article is good evidence of one thing. Well-informed observers in 1937–38 still expected hemp to grow as an industrial crop.
Several of its claims did not hold up:
- The “25,000 products” figure is really a claim about cellulose as a raw material. Any cellulose source could supply those products, not only hemp.
- The paper comparison is a second-hand government estimate, not a field study of yields.
- The decorticators were not commercially proven when the article appeared.
- During the war, mills did process hemp fibre on a large scale. After the war, however, the industry could not compete with other fibres.
Read the article in full; it is short. If you cite it, describe it as a record of what people expected at the time. Do not present it as a technical authority or as proof that hemp was deliberately suppressed.
6. What Historians Say Actually Caused the Act
The main historical accounts come from David Musto, author of The American Disease (1973), and from Richard Bonnie and Charles Whitebread, authors of The Marihuana Conviction (1974). They explain the Act as the result of several causes. None of these causes is a business conspiracy.
- Racial prejudice and moral panic, especially against Mexican and Black Americans. This had built up in local laws and newspapers for two decades before 1937 (see Part 1, section 2). It is the cause with the strongest support in the documents.
- The bureau’s own interests. The FBN was created in 1930. It faced budget cuts in the Great Depression and wanted a wider role. Federal control of cannabis gave it one.
- Real but mistaken public-health concern. At the time, very little was known about how the plant affects the body.
- Moral-reform groups, of the kind that had backed the ban on alcohol. Some accounts include them. Their role in the 1937 Act itself is less well documented than the first three causes.
If you write about why cannabis was banned, start from these four causes. Give the most weight to the first one, since it has the strongest documentary support.
7. Why the Conspiracy Version Keeps Spreading
A conspiracy is easier to tell as a story. It has villains, a motive and a moment when the decision was made. The documented causes are spread across many people. They include an agency seeking a bigger role, racism that was common at the time, campaigners pushing moral causes and lawmakers who paid little attention. Many harmful laws are made this way, and that is much harder to tell as a story.
Cannabis writers also have a practical reason to avoid the conspiracy version. Its main claims can be checked, and the documents do not support them. Each time someone repeats them and gets corrected, readers trust other cannabis writing less.
The documented record shows serious failures without any added drama:
- The Treasury drafted the bill, and the head of the agency that would enforce it pushed it through.
- Congress overrode a medical association’s evidence-based objection.
- It took 32 years, from 1937 to 1969, for the courts to find the law unconstitutional.
Before you share a historical claim about cannabis, find the original document behind it. If you cannot find it, label the claim “unconfirmed” in your post.
8. What This Article Is Not
It is not a defence of the 1937 Act. By any modern standard, the process was poor and the evidence behind it was worse. Woodward’s objections were well founded, and Congress overrode them.
It is not Thai law. Nothing in US legislative history affects what is allowed in Thailand. The Thai rules are:
- Cannabis flower is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568. The Notification was issued under the Thai Traditional Medicine Protection Act B.E. 2542 and has been in force since 26 June 2025.
- Flower may be sold only with a prescription on form PT 33 (ภ.ท.33), for no more than 30 days. Advertising flower and selling it online are prohibited.
- Two Ministerial Regulations of B.E. 2569 tightened licensing in 2026. The Ministerial Regulation on Cannabis or Hemp Extracts came into force on 26 April 2026. It allows licences for extracts above 0.2% THC only for three groups:
- Thai juristic persons that are not “foreign” under the Foreign Business Act B.E. 2542;
- state agencies;
- the Thai Red Cross Society.
- The Ministerial Regulation on Controlled Herbs (No. 2) came into force on 30 April 2026. It tightens the licence criteria for cannabis flower.
- The Cannabis Control Act is still a draft. The Cabinet approved it on 22 September 2026 and sent it to the House of Representatives.
Before you act on any rule, check the current position in Thailand’s Cannabis Rules, 2022 to 2026.
9. 1942: Hemp for Victory and the Government’s Own Reversal
Five years after the Act, the United States needed hemp again. Japan occupied the Philippines, which cut off supplies of abacá, also called “Manila hemp”. Abacá was the main fibre for ships’ ropes.
The Act stayed in force. The government registered wartime growers under the Act itself. It ran a production programme through the Commodity Credit Corporation, a US government agency for farm products, and War Hemp Industries, Inc. Growers were paid for seed and fibre. Production peaked in 1943–44.
The target for 1943 was about 300,000 acres (about 760,000 rai). In earlier years, the crop had covered about 13,000 acres (about 33,000 rai) or less. The area actually planted and harvested was lower than the target, and sources give different figures. Cannabis writing often quotes two more figures: “400,000 pounds of seed” (about 180 tonnes) and “42,000 tons of fibre a year”. Both come from Herer’s book and have not been verified.
The film
To recruit farmers, the US Department of Agriculture (USDA) made a short film in 1942, Hemp for Victory. It is an ordinary training film for farmers. It explains why the crop mattered and how to grow and harvest it. It also shows retting, which means leaving cut stalks to soak or lie in the field so microbes loosen the fibre from the woody core. The film is now in the public domain, so anyone may copy and show it.
Later, people who asked about the film were told by the USDA library and the Library of Congress (the US national library) that no such film existed. According to the commonly cited account, two VHS copies were given to the Library of Congress on 19 May 1989. The donors were Maria Farrow, Carl Packard and Jack Herer. The claim that the film was deliberately erased from official records has no supporting evidence. Poor cataloguing explains the gap, with no need for a cover-up.
What the wartime programme shows
This episode supports the historians’ conclusion in section 6. Once the fibre was needed for the war, the government worked around its own tax system to grow it. This suggests the Act was never aimed at the fibre.
Production fell again after the war. Abacá supplies returned, and synthetic fibres arrived in large volumes. The government stopped buying the whole crop. Without buyers and processing capacity, farmers stopped growing hemp.
Translator’s note: The US hemp crop collapsed when its guaranteed buyer disappeared, not because of a plot. If you plan to grow hemp for fibre or seed in Thailand, check the licensing rules first (Hemp vs High-THC Cannabis: Where Thai Law Draws the Line). Before you plant, get a buyer’s commitment in writing. Confirm where your stalks or seed will be processed. Start with a small plot for one season. It will show your real costs and yield before you expand. The hemp agronomy guide covers what decides yield in the field.
If Herer’s account convinced you, post the claim that convinced you below this topic. Other members can help trace it back to its original source. Some of his claims do hold up, so it is worth checking them one at a time.
Sources
- Taxation of Marihuana: Hearings before the Committee on Ways and Means, House of Representatives, 75th Congress, 1st Session, on H.R. 6385, 27–30 April and 4 May 1937 (includes the testimony of Dr William C. Woodward and H. J. Anslinger).
- US Senate, Committee on Finance, Report No. 900, 75th Congress (1937), on H.R. 6906: https://www.finance.senate.gov/imo/media/doc/75-900Rpt.pdf
- Leary v. United States, 395 U.S. 6 (1969).
- Richard J. Bonnie and Charles H. Whitebread II, The Marihuana Conviction: A History of Marihuana Prohibition in the United States (University Press of Virginia, 1974).
- David F. Musto, The American Disease: Origins of Narcotic Control (Yale University Press, 1973).
- W. A. Swanberg, Citizen Hearst (Scribner, 1961).
- Jack Herer, The Emperor Wears No Clothes (first edition 1985): the source of the conspiracy theory assessed above.
- “New Billion-Dollar Crop”, Popular Mechanics, February 1938.
- US Patents 2,130,523 and 2,130,948 (W. H. Carothers / E. I. du Pont de Nemours), Google Patents: US2130523A - Linear polyamides and their production - Google Patents ; US2130948A - Synthetic fiber - Google Patents
- USDA Economic Research Service, Industrial Hemp in the United States: Status and Market Potential (AGES-001E, 2000), section on the wartime programme.
- USDA, Hemp for Victory (film, 1942).
This is an educational article on US regulatory history. It is general information, not legal advice.