Marijuana is illegal in the US under a variety of federal statutes that criminalize the production, distribution and possession of the substance for any purpose. Regardless, laws in 23 states, the District of Columbia and Guam permit for some legal use of the substance. This ranges from the legalization of full recreational use in Colorado, Washington, Oregon, Alaska and Washington D.C. to the narrower allowance for medicinal use as a defense in court in Maryland. Most of the 23 states only permit the use of small quantities of the substance for medical purposes. The diversity of approaches to the level at which marijuana is legal, coupled with the conflicts with federal law, makes for a complicated history and present state of laws.

The avenues through which states have moved towards legalization of marijuana have been mostly popular vote referenda or the passage of standard legislative acts. In 1998, the District of Columbia city council became the first elected body to pass a bill legalizing medical marijuana. This then went on to pass by popular vote. Due to the federal control of the District by Congress, this attempt was halted, delaying the legalization of medical marijuana there until 2010. California was the first state to legalize medical marijuana through popular vote in 1996 through an amendment to the state constitution. Alaska was the first state to legalize it through legislative activity in 1999, following several failed attempts earlier.

Washington and Colorado were the first two states to legalize marijuana for recreational use. In Colorado [PDF], this was achieved through an amendment to the state constitution that passed with a 55 percent popular vote. The Washington bill [PDF] was an initiative put before the legislature in 2011 that went to popular vote due to legislative inaction and passed by 55.7 percent of the popular vote. A similar initiative was attempted in Oregon [PDF] but failed to pass the popular vote.

Following the passage of these bills, the state administrative agencies have worked to establish rules and protocol on how the substance’s legalization will work. This has been especially complicated due to the conflict with federal law. The Department of Justice announced in August 2013, however, that they had amended their marijuana enforcement policies and would not interfere with states experimenting with legalization.

Several states have recently decriminalized the possession of marijuana, including Vermont and Maryland. Still more states are moving towards legalizing medical marijuana for the first time, including Illinois, where a bill was passed and signed into law in August 2013 to start their medical marijuana program on January 1, 2014. On October 28, 2013, the ACLU filed a lawsuit challenging the Arizona medical marijuana law. Through that suit, the ACLU was able to establish that marijuana extracts do fall under the allowed use of marijuana for medical purposes under the Arizona law.