In the US, the use and possession of cannabis is illegal under federal law for any purpose, by way of the Controlled Substances Act of 1970. Under the CSA, cannabis is classified as a Schedule I substance, determined to have a high potential for abuse and no accepted medical use and thereby prohibits even medical use of the drug. At the state level, policies regarding the medical and recreational use of cannabis vary substantially and in many states conflict with federal law.
The medical use of cannabis is legal in thirty three states, four permanently inhabited U.S. territories, and the District of Columbia. Fourteen other states have laws that limit THC content, so as to allow access to products that contain cannabidiol (CBD). Although cannabis remains a Schedule I drug, the Rohrabacher–Farr amendment prohibits federal prosecution of individuals complying with state cannabis laws.
The recreational use of cannabis is legal in ten states: Alaska, California, Colorado, Maine, Massachusetts, Michigan, Nevada, Oregon, Vermont, and Washington, the District of Columbia, the Northern Mariana Islands and Guam. Another fourteen states plus the U.S. Virgin Islands have decriminalized cannabis.