The Marihuana Tax Act of 1937: How Cannabis Became Illegal

In 1936, you could walk into an American pharmacy and buy a cannabis tincture for a headache, menstrual cramps, or insomnia. Cannabis had sat in the U.S. Pharmacopeia since 1850. By the autumn of 1937, possessing the same plant could land you in a federal penitentiary.

What changed in those eighteen months was not the plant. It was the story told about it.

The Marihuana Tax Act of 1937 is the moment cannabis became, for all practical purposes, illegal in the United States. It is also one of the most misremembered episodes in American drug history. It has real villains, exaggerated villains, and a conspiracy theory that has outlived nearly everyone involved. Let’s separate what actually happened from what we wish had happened. The truth is darker, and more instructive, than the myth.

Before 1937: Cannabis Was Medicine, Not Menace

For most of the 1800s, cannabis was unremarkable. American and European doctors prescribed cannabis extracts for pain, muscle spasms, migraines, and sleep. Major drug companies like Eli Lilly and Parke-Davis sold standardized cannabis preparations. Hemp, the fibrous cousin grown for rope and cloth, had been cultivated in the colonies since the 1600s. Nobody panicked.

Two things shifted public perception in the early 20th century. First, the Pure Food and Drug Act of 1906 began requiring labels on patent medicines, which slowly pulled cannabis out of the unregulated tonic market. Second, and more consequentially, the Mexican Revolution (1910-1920) drove hundreds of thousands of immigrants north into Texas, the Southwest, and Gulf states. They brought with them the recreational smoking of cannabis flower and a Spanish word for it: marihuana.

That word mattered enormously. Most Americans knew “cannabis” and “hemp” as familiar, even wholesome, things. Almost nobody connected those words to the unfamiliar, foreign-sounding “marihuana.” Reframing a known medicine under an exotic name was the first quiet act of the campaign to come, and it worked. By 1931, twenty-nine states had already banned cannabis, mostly through state laws driven by local fear of Mexican laborers and, in northern cities, of Black jazz musicians. (That jazz-club chapter is its own rich story, traced in cannabis in music: from jazz clubs to hip-hop.)

In other words, the racialized panic was building at the state level long before the federal government got involved. To understand how that panic went national, you have to meet the man who carried it there.

Harry Anslinger and the Federal Bureau of Narcotics

In June 1930, the federal government created the Federal Bureau of Narcotics (FBN). Its first commissioner was Harry J. Anslinger, a former railroad cop and Prohibition-era Treasury official. He was appointed by Treasury Secretary Andrew Mellon, who happened to be the uncle, by marriage, of Anslinger’s wife. Anslinger would run the bureau for thirty-two years, across five presidents. No single person shaped American drug policy more.

Here is the detail that popular history almost always leaves out: Anslinger did not start out crusading against cannabis. As late as 1929, he said publicly that cannabis “could not be compared with opium” as a federal problem. For his first four years, he treated marijuana as a regional nuisance and insisted control belonged to the states, not Washington. He repeatedly pushed states to adopt the model Uniform State Narcotic Act instead.

So what changed? Alcohol Prohibition ended on December 5, 1933. That repeal gutted the mission, and the budget justification, of federal enforcement agencies. Anslinger was a bureaucratic survivor first and a moralist second, and his bureau needed a new enemy. Between 1934 and 1936, he reversed himself entirely. The man who had dismissed marijuana spent the next several years building the case that it was a national menace requiring a federal law.

The historical record here is genuinely complicated. Good historians disagree about how much credit, or blame, Anslinger deserves. A 2025 reassessment in the journal Addiction argues he was actually overruled by his superiors and at first resisted a federal law for practical reasons [Becker, 2025]. One thing is not in dispute: the tool he reached for once the campaign began. That tool was fear, manufactured and racialized.

The Propaganda Machine: Gore Files, Hearst, and “Reefer Madness”

To turn a sleepy medicine into “public enemy number one,” Anslinger needed stories. He kept what came to be called the “Gore Files,” a collection of lurid crime cases he attributed to marijuana. The most infamous was Victor Licata, a Tampa teenager who killed his family with an axe in October 1933. Anslinger told the story as proof that cannabis drove users to homicidal madness. Tampa police records, which Anslinger had access to, noted Licata’s pre-existing psychiatric illness. He used the story anyway, because it was useful.

In 1937, Anslinger published “Marijuana: Assassin of Youth” in The American Magazine. It was pure fiction dressed up as fact, framing the drug as a corruptor of innocent white youth. The racial subtext was not subtle. The bureau’s messaging cast marijuana as a poison carried by Mexican immigrants and Black musicians, one that threatened white women and white children. That framing was the engine of the entire campaign, and it seeded stereotypes we’re still unpacking with data today.

The press amplified all of it. William Randolph Hearst’s newspaper empire, twenty-eight major dailies pioneering the sensationalist “yellow journalism” style, ran headlines like “Murder Weed Found Up and Down Coast.” These stories sold papers, and they fed Anslinger’s narrative back to legislators as if it were public demand.

Now, two important corrections, because Professor High deals in evidence, not vibes:

• “Reefer Madness” came after the law, not before. The notorious 1936 film (originally Tell Your Children) is the popular symbol of the prohibition push, but archival research shows it was a privately produced exploitation film. A producer wrote to Anslinger seeking an endorsement in May 1938, after the Tax Act had already passed. Anslinger declined, and the bureau later tried to suppress such films. The movie became famous as 1930s drug propaganda; it was not the cause of the 1937 law.
• The Hearst and DuPont “hemp conspiracy” is largely unproven. Activist Jack Herer’s 1985 book The Emperor Wears No Clothes popularized a tidy theory [Herer, 1985]. In it, Hearst (to protect timber and paper interests) and the DuPont chemical company (to protect newly patented nylon) orchestrated prohibition to kill industrial hemp. It’s a great story. But the evidence is thin. Hearst was a buyer of newsprint, not a seller. Nylon wasn’t sold commercially until 1939. And the Tax Act did not actually ban hemp fiber. No memo, meeting, or corporate directive has ever surfaced. The honest verdict is institutional interests aligning, not a proven plot.

The truth needs no embellishment. A racialized moral panic, amplified by sensational media and weaponized by a bureaucrat fighting for his agency’s survival, was enough.

The 1937 Hearings: Two Hours and One Honest Witness

The bill itself, H.R. 6385, was introduced on April 14, 1937, by Representative Robert L. Doughton of North Carolina, chairman of the powerful House Ways and Means Committee. As chairman, Doughton controlled the witness list and the schedule, a structural advantage that let the bureau stack the deck.

Hearings ran from April 27 to May 4, 1937. The total substantive testimony amounted to roughly two hours. Anslinger testified at length, presenting his crime cases and warning that the “traffic in marihuana” had become “the cause for the greatest national concern.”

The political pressure for the law, as historian David Musto documented, traveled up from local police to state governors to the Treasury, not down from a lone mastermind [Musto, 1972]. The opposition, meanwhile, came from essentially one man.

On May 4, 1937, Dr. William C. Woodward, legislative counsel for the American Medical Association, appeared before the committee. Woodward was a physician and a lawyer, and his testimony was the most substantive challenge the bill ever faced. He raised three devastating points:

1. The Bureau of Prisons had provided no evidence that marijuana was a significant factor in federal crime.
2. The Children’s Bureau and Office of Education had not been consulted about the alleged threat to youth.
3. The Treasury Department had drafted the bill “in secret for two years” without telling the medical profession, even though it would affect every doctor who prescribed cannabis.

Woodward also objected to the word marihuana itself, noting that physicians and the public knew the plant as cannabis, and that the unfamiliar term was being used to obscure what the bill actually targeted. The committee was hostile to him. Rather than engage his evidence, members questioned his motives.

Then came the moment that should be taught in every civics class. When the redrafted bill (H.R. 6906) reached the House floor, a member asked whether the AMA supported it. Representative Fred Vinson, who would later become Chief Justice of the United States, told the House that the AMA “support this bill 100 percent.”

That was false. The AMA had sent its counsel to testify against the bill. Woodward had spent hours objecting to it. By one accounting, the entire House floor debate lasted about ninety-two seconds. The bill passed by voice vote. President Franklin Roosevelt signed it on August 2, 1937, and it took effect October 1.

How a “Tax” Became a Ban

Here’s the clever, cynical mechanism. The Marihuana Tax Act did not, on paper, outlaw cannabis. Congress in 1937 doubted it had the power to ban a plant outright. So Treasury lawyers borrowed a trick from the National Firearms Act: regulation by impossible taxation.

The Act created two tax tiers. If you registered with the federal government and paid an occupational tax, transfers were taxed at $1 per ounce. If you were not registered, the tax jumped to $100 per ounce, roughly $2,100 in today’s money. To get the tax stamp, you had to fill out an order form identifying yourself, the other party, and the amount of marijuana involved. Copies went to the Internal Revenue Service and were made available to law enforcement.

See the trap? To legally buy cannabis, you had to confess, in writing, to a federal agency, to an act that was already a crime in every state. The stamps were almost never issued. The law didn’t say “cannabis is banned.” It said “comply or be prosecuted for tax evasion,” while making compliance functionally impossible. Everyone involved understood the distinction between “tax” and “ban” was a legal fiction.

The consequences were immediate and human. On October 1, 1937, the day the law took effect, the FBN and Denver police arrested Samuel Caldwell for dealing and Moses Baca for possession, among the first people prosecuted under the Act. Caldwell was sentenced to four years in Leavenworth. The era of federal cannabis prohibition had begun.

Aftermath: From Tax Stamp to Schedule I

The Act stood for thirty-two years. It withstood the 1944 La Guardia Committee report, which found that New York City’s marijuana use was far less dangerous than Anslinger claimed. It survived the postwar decades, even as Anslinger swapped his “violence” narrative for a “communist susceptibility” narrative and then a “gateway drug” narrative, deploying whichever story was politically useful.

What finally killed it was the Fifth Amendment, the very self-incrimination trap built into its design.

In Leary v. United States (1969), Harvard psychologist and counterculture figure Timothy Leary had been convicted under the Tax Act for marijuana found in his car at the Texas-Mexico border. His lawyers argued that the Act forced him to incriminate himself. To comply with the tax, he would have had to identify himself as someone holding a substance that was illegal under state law. The Supreme Court agreed, unanimously. Justice John Marshall Harlan II wrote the opinion striking the Marihuana Tax Act down as unconstitutional [Harlan, 1969].

Congress did not respond by legalizing cannabis. It responded by building a sturdier prohibition. In 1970, the Comprehensive Drug Abuse Prevention and Control Act, signed by President Nixon, replaced the tax-stamp scheme with the Controlled Substances Act (CSA), which classified marijuana as a Schedule I drug, the most restrictive category, reserved for substances deemed to have high abuse potential and no accepted medical use. That classification has remained essentially unchanged for over fifty years, even as a majority of states have legalized cannabis in some form. (For where that fight stands today, see our guide to cannabis legalization in the United States in 2026, the state-by-state map of where weed is legal, and the recent move toward rescheduling cannabis to Schedule III.)

Why This Still Matters in 2026

You might think a 1937 tax law is ancient history. It isn’t. The architecture of cannabis prohibition we live with today, the federal-state conflict, the Schedule I straitjacket, the racially lopsided enforcement, and even the punishing tax burden cannabis businesses still carry, was poured in that 1937 foundation and merely reinforced in 1970. Some of the era’s myths also calcified into “common knowledge,” like the notion that cannabis is inevitably habit-forming, a claim that research suggests is far more nuanced than the propaganda implied.

The 1937 Act is also a permanent case study in how bad policy gets made: define an unfamiliar word, attach it to a feared group, manufacture a public demand through sensational media, hold a brief hearing, ignore the one expert who shows up to object, and pass the law before anyone can read it. That playbook didn’t die in 1937. Recognizing it is the whole point of cannabis education, which is exactly why we think most cannabis education today is broken and worth fixing with evidence instead of slogans.

The plant didn’t change in 1937. The story did. Almost a century later, we’re finally getting back to asking what cannabis actually does, strain by strain and terpene by terpene, instead of what a railroad cop with a budget problem told us it did. That’s progress worth understanding. And it starts with knowing where the fear came from.

Key Takeaways

• Cannabis was legal medicine before 1937. It sat in the U.S. Pharmacopeia and on pharmacy shelves for decades.
• The word “marihuana” was a tool. An unfamiliar Spanish term hid the fact that the “menace” was just cannabis.
• Anslinger pivoted for survival. He dismissed marijuana for years, then turned on it after alcohol Prohibition ended in 1933 threatened his bureau.
• The propaganda was racialized, not corporate. The Hearst/DuPont “hemp conspiracy” is largely unproven; the racial moral panic is well documented.
• The “tax” was a ban in disguise. A $100-per-ounce stamp and self-incriminating order forms made legal cannabis impossible.
• Process beat evidence. Two hours of hearings, one honest witness ignored, and a roughly 92-second floor debate.
• It still shapes today. Leary v. United States (1969) killed the Act, but the 1970 Controlled Substances Act rebuilt prohibition as Schedule I, where cannabis largely remains.

Frequently Asked Questions

Did the Marihuana Tax Act of 1937 actually make cannabis illegal? Not technically, but effectively yes. The Act used a tax-stamp scheme: a $1-per-ounce tax for registered handlers and a punitive $100-per-ounce tax for everyone else, plus order forms that required self-identification to authorities. Because compliance was nearly impossible and the stamps were rarely issued, the law functioned as de facto prohibition. Read our overview of the modern legal landscape in cannabis legalization in the United States in 2026.

Was Harry Anslinger really the villain of cannabis prohibition? He was central, but more complicated than the cartoon. Anslinger initially opposed a federal law and treated marijuana as a state-level issue. After alcohol Prohibition ended in 1933 and threatened his bureau’s budget, he reversed course and ran a fear-driven, racially charged campaign. Recent historical scholarship (a 2025 Addiction paper by Hall and Yeates) argues his role was somewhat overstated and that bureaucratic pressure from above and below mattered too.

Was there a Hearst-DuPont conspiracy to ban hemp? This is the most popular myth, and it’s largely unsupported. Popularized by Jack Herer’s 1985 book, the theory claims Hearst (paper/timber) and DuPont (nylon) conspired to kill hemp. But Hearst bought newsprint rather than sold it, nylon wasn’t commercial until 1939, the Act didn’t ban hemp fiber, and no documentary evidence of coordination exists. Hearst’s sensational anti-marijuana coverage was real; the corporate conspiracy is not proven. This connects to a broader theme: why crowd-sourced and pop narratives so often mislead.

How was the Marihuana Tax Act finally struck down? In Leary v. United States (1969), the Supreme Court unanimously ruled that the Act’s self-incrimination requirement violated the Fifth Amendment. Congress replaced it the next year with the Controlled Substances Act of 1970, which placed cannabis in Schedule I, where it largely remains. See what cannabis rescheduling to Schedule III means for you.

Is cannabis a gateway drug, as Anslinger later claimed? The “gateway” framing was one of several narratives Anslinger deployed after his “violence” story lost traction. Modern science does not support a simple causal gateway. We break down the evidence in is cannabis a gateway drug?

Want More Cannabis History?

If this story hooked you, the rabbit hole goes deep. Start with the full history of cannabis from ancient medicine to modern science, then trace how the 1937 propaganda echoed through pop culture in from “Reefer Madness” to “The Dude”: cannabis in cinema. For a lighter chapter of cannabis lore, see the history of 420: how a number became cannabis culture. And to see how far the science has come since 1937, read from prohibition to precision: 80 years of cannabis science.

Sources

• Becker, H.S. et al. “Correcting popular misconceptions about the origins of the Marihuana Tax Act of 1937.” Addiction (December 2025). Link
• Musto, D.F. “The History of the Marihuana Tax Act of 1937.” Archives of General Psychiatry / Schaffer Library of Drug Policy. Link
• Leary v. United States, 395 U.S. 6 (1969). Supreme Court of the United States. Link
• Congressional Research Service. “The Evolution of Marijuana as a Controlled Substance and the Federal-State Policy Gap” (R44782). Link
• “Marihuana Tax Act of 1937.” Wikipedia. Link
• Statement of H.J. Anslinger, Congressional Hearings on H.R. 6385 (1937). Link
• “Busted: America’s War on Marijuana.” FRONTLINE, PBS. Link

Professor High writes about cannabis with curiosity and a healthy respect for evidence. History included.