Four states and Washington, D.C., allow recreational marijuana. Nineteen states allow it for medical purposes, and 14 have decriminalized it.
In the states with outright legalization, possession and consumption of marijuana is legal for people age 21 and older. Alaska, Oregon, Washington and Colorado have already instated or are in the process of introducing a model whereby marijuana can be legally sold, taxed and regulated.
Washington, D.C., has only legalized possession and growing for the time being, but its city council will likely move to tax and regulate soon.
In the additional 19 states where marijuana for medicinal purposes is legal, regulation varies widely, with certain states, such as California, so lax about criteria for a medical marijuana card that it ultimately assumes a quasi-legal status.
States where marijuana has been decriminalized have softened the penalties associated with possessing the drug, often limiting or eliminating prison time and opting for fines instead. Like with medical marijuana, states vary a great deal in their laws, and decriminalization does not do away with harsh penalties for possessing or trafficking large amounts of the plant.