The Marihuana Tax Act of 1937 ended a century of legal cannabis medicine in America. Behind it: racist propaganda, political lobbying and fabricated hysteria. Here is the full story.
Before 1937, cannabis had been legal and widely used in the United States for over three centuries. Hemp cultivation was mandated by colonial law from 1619. Pharmaceutical cannabis tinctures appeared in the US Pharmacopoeia in the 1850s. By 1900, major pharmaceutical companies including Eli Lilly, Squibb and Parke-Davis sold standardised cannabis preparations marketed for insomnia, pain, menstrual cramps and nervous conditions. Physicians prescribed cannabis routinely; it was not considered a problematic drug.
The Harrison Narcotics Tax Act of 1914 regulated opiates and cocaine but explicitly excluded cannabis. State-level restrictions began appearing in the 1910s–1920s, often targeting Mexican immigrant communities in southwestern states. Utah, California, Texas and Louisiana passed cannabis prohibitions in the 1910s explicitly through anti-Mexican legislation. Cannabis use among Mexican migrant workers was used to justify racially targeted policing without naming race explicitly in the statutes. This state-level prohibition movement provided the political template that Harry Anslinger would scale federally in the 1930s. The contrast with today’s legalisation movement is striking.
Harry Jacob Anslinger became the first commissioner of the Federal Bureau of Narcotics in 1930, arriving at a moment when alcohol prohibition was ending and his bureau needed a new mission to justify its budget and existence. Anslinger initially dismissed cannabis as a minor problem — internal memos show he considered it less dangerous than alcohol. His position changed dramatically when alcohol prohibition ended in 1933 and his bureau faced defunding pressure.
Anslinger launched a nationwide propaganda campaign depicting cannabis as uniquely dangerous, violence-inducing and morally corrosive. He compiled a file he called the “Gore Files” — a collection of lurid criminal cases he attributed to cannabis, many of dubious factual accuracy. He wrote and planted sensationalist articles in major newspapers. He explicitly connected cannabis use to racial minorities in public communications: “There are 100,000 total marijuana smokers in the US, and most are Negroes, Hispanics, Filipinos and entertainers. Their Satanic music, jazz and swing, result from marijuana use. This marijuana causes white women to seek sexual relations with Negroes.” This direct quote from Anslinger’s congressional testimony represents the explicit racial framing of federal cannabis prohibition.
Anslinger also cultivated relationships with newspaper publisher William Randolph Hearst, whose sensationalist coverage of cannabis — using the word “marihuana” to make it sound foreign and threatening — reached millions of American readers in the mid-1930s. The collaboration between government propaganda and media amplification created a moral panic that overwhelmed available medical evidence. Discover how this era continued into Nixon’s policy in our War on Drugs guide.
The congressional hearings on the Marihuana Tax Act in April-July 1937 lasted fewer than two hours and were notable for how little scrutiny was applied to Anslinger’s claims. Witnesses supporting prohibition included Anslinger and a collection of state officials. The American Medical Association sent Dr. William Woodward to testify against the bill. Woodward argued that the AMA had only recently become aware the act applied to cannabis at all — because it had been advertised using the unfamiliar term “marihuana” rather than “cannabis” — and that eliminating medical cannabis would harm patients and medical research.
Congressman Fred Vinson (later Supreme Court Chief Justice) dismissed Woodward’s testimony with hostility. The bill passed both chambers of Congress with minimal debate. President Franklin D. Roosevelt signed it on August 2, 1937. The law imposed a $1 tax per ounce for medical and industrial transactions, but required transfers to be registered and taxed — and possession of untaxed cannabis was a criminal offence. The administrative burden and legal exposure effectively ended all commercial cannabis activity. By 1942, cannabis was removed from the US Pharmacopoeia entirely.
The Marihuana Tax Act’s legal foundation collapsed in 1969 when the Supreme Court ruled in Leary v. United States that the act violated the Fifth Amendment’s self-incrimination clause — because registering to pay the cannabis tax required admitting illegal drug possession. Timothy Leary, the Harvard psychologist and counterculture figure, had deliberately challenged the law by transporting cannabis across the US-Mexico border without paying the tax, leading to a landmark constitutional ruling.
Congress responded by passing the Comprehensive Drug Abuse Prevention and Control Act of 1970, which included the Controlled Substances Act (CSA). The CSA placed cannabis in Schedule I — the most restrictive category, defined as substances with high abuse potential, no currently accepted medical use and a lack of accepted safety for use under medical supervision. Heroin also sits in Schedule I. Cocaine and methamphetamine are Schedule II, meaning they are medically accepted and thus less restricted under federal law than cannabis.
President Nixon requested a scientific review of cannabis scheduling from the Shafer Commission in 1972. The commission’s report, “Marihuana: A Signal of Misunderstanding,” recommended decriminalisation, finding no evidence that cannabis warranted Schedule I classification. Nixon rejected the report and intensified enforcement. His aide John Ehrlichman later confirmed in a 1994 interview that the War on Drugs was designed to target Nixon’s political enemies — Black people and antiwar protesters. The full political context is in our Nixon War on Drugs guide. The legalisation movement has spent decades dismantling what 1937 and 1970 built. See also the DEA scheduling information for current federal status.
| Year | Event | Impact |
|---|---|---|
| 1914 | Harrison Narcotics Tax Act | Regulates opiates and cocaine; cannabis excluded |
| 1930 | Anslinger appointed FBN commissioner | Federal cannabis propaganda campaign begins |
| 1936 | Reefer Madness film released | Peak of anti-cannabis media hysteria |
| 1937 | Marihuana Tax Act signed | Effective federal prohibition begins |
| 1942 | Cannabis removed from US Pharmacopoeia | Medical cannabis use officially ends in America |
| 1969 | Leary v. United States ruling | Supreme Court strikes down 1937 Tax Act as unconstitutional |
| 1970 | Controlled Substances Act | Cannabis placed Schedule I — above cocaine and meth |
The Marihuana Tax Act of 1937 imposed prohibitive taxes and registration requirements on cannabis producers, sellers and buyers in the United States. While technically a tax law, it effectively criminalised cannabis by making legal use economically and administratively impossible.
Harry Anslinger was the first commissioner of the Federal Bureau of Narcotics (1930-1962). He led the campaign to prohibit cannabis, using racist propaganda linking marijuana to Black jazz musicians and Mexican immigrants, fabricated stories of violence, and relentless congressional lobbying.
No. The American Medical Association actively opposed the Marihuana Tax Act, arguing it would eliminate legitimate medical cannabis use that physicians had relied on for decades. The AMA objection was overridden by Congress.
The Controlled Substances Act of 1970 replaced the 1937 Tax Act after the Supreme Court struck down the original law in Leary v. United States (1969). The CSA placed cannabis in Schedule I, the most restrictive category, alongside heroin.
Historians broadly agree that racism was a primary driver. Anslinger explicitly associated cannabis with Black jazz musicians and Mexican immigrants in congressional testimony and press campaigns. The term marihuana was promoted specifically to create a foreign-sounding association.
Reefer Madness (1936) was a propaganda film depicting cannabis causing murder, rape and insanity. It was part of a broader media campaign that shaped public perception ahead of the 1937 legislation. The film later became a cult classic and symbol of anti-cannabis propaganda absurdity.