Marijuana—also known as marihuana or cannabis—is classified as a controlled substance under federal law, and its possession, use, and distribution is illegal. See 21 U.S.C. §812.

But many states have recently passed laws that generally legalize marijuana in some form. For example, Alaska, California, Colorado, Illinois, Maine, Massachusetts, Michigan, Nevada, Oregon, Vermont, and Washington have enacted laws legalizing marijuana for recreational use.

The District of Columbia allows all citizens over the age of 21 to possess up to two ounces of marijuana, to use and grow marijuana on private property, and to exchange marijuana between persons as long as no money, goods, or services are exchanged.

And some states that do not allow recreational use of marijuana do allow limited use of marijuana to treat symptoms of illness and other conditions—known as medical marijuana. States that allow limited use of medical marijuana include Arkansas, Arizona, Connecticut, Delaware, Florida, Hawaii, Louisiana, Maryland, Massachusetts, Minnesota, Missouri, Montana, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, Utah, Vermont, and West Virginia. The medical marijuana laws in some of these states are broader than others, with some states only allowing use of cannabis-infused products such as oils and pills. Federal law prohibits health care practitioners from writing a prescription for medical marijuana, so practitioners in medical marijuana states write a recommendation for medical marijuana.

Other states have not legalized marijuana, but have decriminalized it—meaning possession of small amounts of marijuana is not punishable by jail or prison time, but may be punished with a fine. States that have decriminalized possession of marijuana under limited circumstances include Connecticut, Maryland, Mississippi, Nebraska, New Hampshire, New Mexico, New York, North Carolina, and Virginia.

Marijuana laws are generally located in a state’s statutes—often in the penal or criminal code, or in the health and safety code.

In Arizona, marijuana is regulated both by federal and state laws. Federally, marijuana is classified as a Schedule I controlled substance under the Controlled Substances Act (21 U.S.C. §812), making its possession, use, and distribution illegal. However, Arizona has passed state laws that diverge from federal policy. Arizona permits the use of marijuana for medical purposes under the Arizona Medical Marijuana Act (AMMA), which allows individuals with certain qualifying conditions to use medical marijuana if recommended by a physician. Additionally, as of November 2020, Arizona voters approved Proposition 207, the Smart and Safe Arizona Act, which legalizes the recreational use of marijuana for adults 21 years and older. Adults are allowed to possess up to one ounce of marijuana, with no more than 5 grams being marijuana concentrate, and they can also grow up to six marijuana plants in their residences, provided the plants are within a lockable, enclosed area and out of public view. Despite state-level legalization, it is important to note that federal law still prohibits marijuana use and possession, which can lead to legal conflicts.