In the United States, the use of cannabis for medical purposes is legal in 41 states, four out of five permanently inhabited U.S. territories, and the District of Columbia, as of July 2025. Ten other states have more restrictive laws limiting THC content, for the purpose of allowing access to products that are rich in cannabidiol (CBD), a non-psychoactive component of cannabis. There is significant variation in medical cannabis laws from state to state, including how it is produced and distributed, how it can be consumed, and what medical conditions it can be used for.
The first state to effectively legalize medical cannabis was California in 1996, when voters approved Proposition 215 by a 56–44 margin. Several states followed with successful ballot initiatives in 1998, and in 2000 Hawaii became the first to legalize through an act of state legislature. Legalization of medical cannabis had spread to a majority of states by 2016.
State-regulated medical cannabis was moved to Schedule III of the Controlled Substances Act in April 2026 by acting U.S. Attorney General Todd Blanche.
Early medical use in the U.S. The medical use of cannabis dates back thousands of years, to ancient China, India, and Egypt. It was popularized in Western medicine by the Irish physician William Brooke O'Shaughnessy, who was introduced to the drug in the 1830s while living abroad in India. O'Shaughnessy documented a number of medical applications for cannabis from the experiments he conducted, noting in particular its analgesic and anticonvulsant effects. He returned to England with a supply of cannabis in 1842, after which its use as medicine quickly spread throughout Europe and the United States.
Cannabis was entered into the United States Pharmacopeia in 1850, as a treatment for neuralgia, tetanus, typhus, cholera, rabies, dysentery, alcoholism, opiate addiction, anthrax, leprosy, incontinence, snakebite, gout, convulsive disorders, tonsillitis, insanity, excessive menstrual bleeding, and uterine bleeding. It was widely available in pharmacies and even grocery stores during the latter half of the 19th century, priced affordably relative to other drugs with no requirement for a doctor's prescription. Cannabis was commonly sold in tincture form by Parke-Davis, Eli Lilly, E. R. Squibb & Sons, and other drug manufacturers.
By the end of the 19th century, the use of cannabis in medicine had declined due to a number of factors, including difficulty in controlling dosages and the rise in popularity of synthetic and opium-derived drugs. The advent of the hypodermic syringe also allowed these drugs to be injected for immediate effect, in contrast to cannabis which is not water-soluble and therefore cannot be injected. Additionally, as fears regarding the recreational use of cannabis began to take hold (prompted by sensationalist media reports and government propaganda campaigns), states began passing legislation to restrict the sale and possession of cannabis, eliminating its availability as an over-the-counter drug. By 1936, every state had passed a law of this manner.
The use of cannabis as medicine further declined with the passage of the Marihuana Tax Act of 1937. The purpose of the act was to prohibit all non-medical use of cannabis in the U.S.; however, it also had the effect of severely curtailing medical use of the drug, due to new fees and regulatory requirements put in place that imposed a significant burden on doctors prescribing cannabis. For this reason the American Medical Association opposed the Marihuana Tax Act of 1937, but to no avail. Cannabis was removed from the U.S. Pharmacopeia in 1941, at the urging of famed anti-cannabis crusader Harry Anslinger.
During the 1960s, as large numbers of people began to use cannabis recreationally, the medical utility of cannabis was rediscovered by some as anecdotes began to appear about its effectiveness in treating a variety of medical conditions. It was officially banned for even medical use, however, following the passage of the 1970 Controlled Substances Act. Despite the strict federal prohibition in place, cannabis continued to gain renewed interest as medicine in the 1970s and 1980s, in particular due to the testimonials of cancer and AIDS patients who reported significant relief from the effects of chemotherapy and wasting syndrome. The smoking method of consumption – popularized by recreational users of the drug – offered particular aid to patients who had trouble keeping down oral medication, and also offered advantages in terms of rapid onset of action and the ability to more carefully control dosages.
Federal policy Controlled Substances Act On October 27, 1970, the Comprehensive Drug Abuse Prevention and Control Act was signed into law by President Richard Nixon. Title II of the act – the Controlled Substances Act – established a system under which all controlled substances are categorized, varying from Schedule I (the strictest classification) to Schedule V (the least strict). Cannabis was placed in the Schedule I category, assumed to have a high potential for abuse and no accepted medical use – thereby prohibiting its use for any purpose. This placement was intended only as a temporary measure, however, pending the results of a commission formed under decree of the CSA to study the dangers of cannabis. Formally known as the National Commission on Marihuana and Drug Abuse, the Shafer Commission – led by former Pennsylvania governor Raymond P. Shafer – submitted the first of its two final reports to the President and Congress in March 1972. Although the report did not address the subject of scheduling, it found that the harms caused by cannabis were overstated, and recommended removal of criminal penalties for possession and distribution of small amounts of the drug. Despite these findings, no action was subsequently taken to move cannabis into a less restrictive category, and the Schedule I classification of cannabis remains in place, alongside other drugs such as heroin, LSD, MDMA, DMT, and peyote – none of which can be prescribed. Schedule II drugs – determined to have a high potential for abuse but also some accepted medical use (thus able to be prescribed) – include cocaine, PCP, methamphetamine, oxycodone, and fentanyl.
Rescheduling After enactment of the Controlled Substances Act, there were a number of efforts seeking to place cannabis in a less restrictive category. The Drug Enforcement Administration is granted authority under the CSA to change the classification of any drug, based upon the recommendation of the Food and Drug Administration which evaluates all drugs for safety and efficacy. A 2016 FDA review concluded that cannabis has "no currently accepted medical use in treatment in the United States", in response to a petition filed with the DEA in 2011 by the governors of Washington and Rhode Island. Previous efforts to petition the DEA for rescheduling have also been unsuccessful, spanning the years 1972–1994, 1995–2001, and 2002–2013. Congressional attempts to reschedule have failed as well, including a 1981 bill introduced by Representatives Stewart McKinney and Newt Gingrich that grew to 84 cosponsors but never received a floor vote. However, President Joe Biden announced in October 2022 that he would ask the Secretary of Health and Human Services and Attorney General to initiate a review as to how cannabis should be scheduled under federal law, adding that the Schedule I classification of cannabis "makes no sense". In August 2023, following a review by the Food and Drug Administration, the Department of Health and Human Services issued a recommendation to the DEA that cannabis be moved to Schedule III. In April 2024, the DEA confirmed its intention to reclassify cannabis as a Schedule III drug, pending review by the Office of Management and Budget, a public comment period, and review by an administrative judge.
The classification of cannabis as a Schedule I drug was first challenged by the National Organization for the Reform of Marijuana Laws (NORML) in a 1972 petition to the Bureau of Narcotics and Dangerous Drugs (which was merged with other agencies to form the DEA in 1973). After a decade of legal battles in which the DEA refused to consider the petition, public hearings were finally held on the matter beginning in 1986. In September 1988, after two years of extensive public hearings, DEA Chief Administrative Law Judge Francis L. Young ruled in favor of moving cannabis to a Schedule II classification, finding that "Marijuana, in its natural form, is one of the safest therapeutically active substances known to man." Young concluded: "The evidence in this record clearly shows that marijuana has been accepted as capable of relieving the distress of great numbers of very ill people, and doing so with safety under medical supervision. It would be unreasonable, arbitrary and capricious for DEA to continue to stand between those sufferers and the benefits of this substance in light of the evidence in this record." As Young's ruling was only a non-binding recommendation, however, it was rejected by DEA Administrator John Lawn in December 1989. In February 1994, a final ruling on the original 1972 petition was issued when a U.S. Court of Appeals upheld the decision to keep cannabis a Schedule I drug.
Acting United States Attorney General Todd Blanche reclassified state-licensed medical cannabis to Schedule III on April 23, 2026.
Compassionate IND program Despite an official policy denying the medical value of cannabis, the federal government began providing the drug to a limited number of patients through the Compassionate Investigational New Drug program in 1978. The program was created following a lawsuit filed by Robert Randall, a Washington, D.C. resident who was arrested for cultivating cannabis in 1975. Citing the glaucoma that threatened to take his eyesight, Randall employed a medical necessity defense at trial to justify his use of cannabis. The charges against Randall were dismissed, and as a result of an ensuing petition filed with the FDA, Randall became the first person to receive cannabis from the federal government in 1976. After his supply was cut off in 1978, he filed a lawsuit to have it restored, setting in motion the creation of the Compassionate Investigational New Drug program shortly thereafter. The program allowed patients with serious medical conditions to receive a regular supply of cannabis from the federal government; however, only 13 ended up participating due to the complicated and drawn-out application process involved.
The Compassionate IND program was closed to new patients in 1992, due to a flood of new applications from AIDS patients and concerns that the program undercut Bush administration efforts to discourage illegal drug use. James O. Mason, the head of U.S. Public Health Service, explained that keeping the program in place created the perception that "this stuff can't be so bad", and noted that AIDS patients provided with cannabis would be more likely to engage in unsafe sex. Twenty-eight applications that had recently been approved were rescinded, and only the 13 individuals who were already receiving cannabis were allowed to do so moving forward. All but two of the patients have since died; the surviving two patients are the only persons who currently receive cannabis through the program.
Federal enforcement Clinton administration