Cannabis was legal, commercially cultivated and medically listed in the United States for most of the country's history. It was banned within a few decades, and twice during that period official bodies examined the evidence and recommended against the direction being taken. Both were overruled.
Before Prohibition
Cannabis appeared in the United States Pharmacopoeia from 1850, and cannabis extracts were sold as medicine for pain, spasm and sleep. Hemp had been a significant agricultural crop for rope and textiles since the colonial period.
The 1906 Pure Food and Drug Act required labelling of certain substances including cannabis, which was regulation through disclosure rather than prohibition.
State-level restrictions began appearing in the 1910s and 1920s, and the timing is informative. Many followed the Mexican Revolution and the migration that came with it, and the campaigns were frequently explicit in linking cannabis to Mexican immigrants.
The word marihuana was foregrounded during this period precisely because it sounded foreign. Americans knew the plant as cannabis or hemp, and a Spanish-derived name made it easier to present as something new and alien.
Anslinger and the 1937 Act
Harry Anslinger became the first commissioner of the Federal Bureau of Narcotics in 1930. Under his leadership the bureau pursued federal cannabis prohibition through a campaign built on lurid claims about violence and insanity, with testimony and press material that relied heavily on racial themes.
The film Reefer Madness, released in 1936, is the cultural artefact people remember. The legislative result was the Marihuana Tax Act of 1937, which imposed registration and a prohibitive tax on cannabis transactions. It was nominally a tax measure and functioned as prohibition, since complying with it was made effectively impossible.
The American Medical Association opposed the Act, objecting both to the loss of a medicine and to the process. It passed anyway, and cannabis was removed from the United States Pharmacopoeia in 1942.
The Report That Was Buried
New York's mayor Fiorello La Guardia commissioned a study, and the La Guardia Committee Report appeared in 1944. It examined the claims underpinning prohibition and contradicted most of them, finding no evidence that cannabis caused violent crime, insanity or opiate addiction, and concluding that the dangers had been overstated.
Anslinger attacked the report and worked to discredit it. It had little effect on policy, which is the pattern worth noting: the evidence was examined, it did not support the policy, and the policy continued.
Escalation
Schedule I and the Second Ignored Commission
The Controlled Substances Act of 1970 created the modern scheduling system and placed cannabis in Schedule I, defined as high abuse potential with no accepted medical use and lack of accepted safety.
Cannabis was placed there provisionally, pending a commission's findings. The National Commission on Marihuana and Drug Abuse, known as the Shafer Commission after its chairman, reported in 1972 and recommended decriminalising possession for personal use, concluding that criminal penalties caused more harm than the drug.
President Nixon rejected the recommendation. Cannabis stayed in Schedule I, where it remains, and the Schedule I designation then made the research required to revisit it structurally difficult, a circularity that persisted for decades.
A quotation attributed to Nixon aide John Ehrlichman, published in a 1994 interview many years after it was supposedly said, describes the drug war as a deliberate strategy to target antiwar and Black communities. It is widely cited and has been questioned by historians and by Ehrlichman's family. It is worth knowing about and worth treating as contested testimony rather than settled fact, particularly since the documented record of racially disparate enforcement does not depend on it.
The Enforcement Record
What followed is well documented. Cannabis possession arrests rose into the hundreds of thousands annually, becoming one of the most common grounds for criminal justice contact in the country.
Analysis by the American Civil Liberties Union found Black people were arrested for cannabis possession at roughly 3.6 times the rate of white people nationally despite broadly similar rates of use, with far larger disparities in some counties.
The Turn
Reform began at the margins and accelerated. California's Proposition 215 in 1996 created the first state medical programme. Colorado and Washington voted for adult-use legalisation in 2012, with retail sales beginning in 2014. Uruguay legalised nationally in 2013, Canada in 2018.
In 2018 the FDA approved Epidiolex, a cannabis-derived medicine, which sat awkwardly beside a Schedule I classification premised on no accepted medical use. In 2020 the UN Commission on Narcotic Drugs removed cannabis from Schedule IV of the 1961 Convention, its most restrictive category.
Bottom Line
Cannabis was a listed medicine and a commercial crop before being banned through the 1937 Marihuana Tax Act, over AMA objection, following campaigns that leaned on racial anxiety. The 1944 La Guardia Report contradicted the claims behind prohibition and was dismissed. The 1972 Shafer Commission recommended decriminalisation and was overruled. Schedule I then made the research needed to revisit it difficult, which is why the classification outlasted the evidence for it.
Disclaimer: This article is for educational purposes only and does not constitute legal advice.