In the United States, the use of cannabis for medical purposes is legal in 37 states, four out of five permanently inhabited U.S. territories, and the District of Columbia, as of February 2022. Eleven 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. By 2016, legalization of medical cannabis had spread to a majority of states. At the federal level, cannabis remains a prohibited substance by way of the Controlled Substances Act of 1970. Under the CSA, the Drug Enforcement Administration classifies cannabis as a Schedule I drug, determined to have a high potential for abuse and no accepted medical use – thereby prohibiting its use for any purpose. The Justice Department has enforced this policy through various means, including criminal prosecutions, civil asset forfeiture, and paramilitary-style raids targeting medical cannabis providers, and various penalties threatened or initiated against other individuals involved in state-legal medical cannabis activities (doctors, landlords, state officials and employees). In December 2014, however, the Rohrabacher–Farr amendment was signed into law, prohibiting the Justice Department from spending funds to interfere with the implementation of state medical cannabis laws. In October 2022, President Joe Biden announced 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". 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