The sale, use, and possession of all forms of cannabis are illicit under United States federal law. Under the Controlled Substance Act, enacted in 1970, marijuana is still considered to have "no accepted medicinal use" and has a high potential for abuse, dependence, and physical/psychological abuse. The federal government maintains an effort to keep cannabis illegal, yet several states have passed legislation that permits medical and recreational use of the substance.
Medicinal cannabis is currently legal in thirty-one states - Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Illinois, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, and West Virginia.
As of 2018, nine states - Alaska, California, Colorado, Maine, Massachusetts, Nevada, Oregon, Vermont, and Washington have legalized the sale and possession of marijuana for both medical and recreational use.
Decriminalization of the substance has been put into effect in Connecticut, Delaware, Illinois, Maryland, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New York, North Carolina, Ohio, Rhode Island, and the U.S. Virgin Islands.
Marijuana remains illegal in American Samoa, Idaho, Kansas, and South Dakota. In the following states, all purposes, and possession of even small amounts is a crime. South Dakota is the only state in the U.S. that prohibits the ingestion of controlled substances. Testing positive for cannabis can be a felony offense.