(BPT) – As the medical community and many Americans come to accept the use of marijuana to treat a range of diseases and symptoms, state legislators are working to keep pace with laws concerning marijuana for medical use.

Numerous polls have indicated that a growing majority of Americans believe that medical marijuana should be legal throughout the country. Yet among the states, and even at the federal level, the merits of marijuana as a medical treatment are far from settled.

Forty-two states and the District of Columbia have proposed or enacted legislation regarding medicinal and recreational use of marijuana, according to a study by WestlawNext, the nation’s leading online legal research service. While California made national headlines when the state legalized medical marijuana in 1996, Virginia was the first state to legalize marijuana for certain medical purposes in 1979, fully 17 years before California’s law was signed.

Despite a shift toward public acceptance of medical marijuana use, only 24 states and the District of Columbia have made it legal. Legislation has been proposed in another 18 states, but not all have followed suit, with Idaho passing legislation reaffirming its stand against the legalization of marijuana altogether.

According to the Marijuana Policy Project, an estimated 2.4 million U.S. citizens are medical marijuana patients as of December 2012. Where it is legal, medical marijuana is available as a prescribed treatment through a medical doctor, either in a smokeable or ingestible form (pill), and typically available through state-administered dispensaries. An inhalable form, which technically uses key chemical compounds of marijuana, is legal in the United Kingdom and many other countries, and is in clinical trials for use in the United States.

Some of the more common, but very serious, medical conditions for which medicinal marijuana is being prescribed include: multiple sclerosis, terminal cancer, muscular dystrophy, inflammatory bowel disease (including Crohn’s disease), seizure disorder (including epilepsy), glaucoma, and HIV/AIDS, among others.

In addition to legalizing medical marijuana for adults, 20 states have addressed the issue of offering medical marijuana, prescribed in pill form, for sick children. Seventeen states allow the use of medical marijuana for minors when prescribed by a doctor, according to the National Organization for the Reform Marijuana Laws (NORML). A law in New Jersey is currently being considered that would require the approval from both a doctor and psychiatrist. Connecticut and Illinois prohibit medical marijuana for sick children, while allowing its use by adults.

Marijuana is still classified as a Schedule I substance under the-Controlled Substances Act, making the distribution of marijuana, even for medical purposes, a federal crime, according to the National Conference of State Legislatures. However, in October 2009, the Obama Administration asked federal prosecutors to stop prosecuting people who possess medical marijuana in accordance with local laws.

“Many states adopt the same test for classifying a Schedule I substance as the federal Controlled Substances Act (CSA),” said Michael Carlson, reference attorney at Thomson Reuters.-“Generally, a Schedule I drug is said to have no accepted medical use-but even a cursory review of proposed legislation shows that there’s a general trend towards liberalizing marijuana laws especially for medical use.-Authors of the first CSA-commissioned study were not persuaded by reports from organizations such as the New England Journal of Medicine, which recommended legalization in 1972.-Clearly, legislators are rethinking the issue.”

Carlson also noted that medical marijuana patients can be prosecuted if they possess marijuana on federal land, such as a national park or federally subsidized housing, even if the use of marijuana is legal in that state for medicinal purposes.

Medical marijuana laws also vary considerably from state to state.- For example, only a handful of states, such as Arizona, Delaware, Maine, Michigan, Nevada and Rhode Island, offer medical marijuana reciprocity agreements, which allow qualifying patients to use medical marijuana between states that have legalized its use.

Possession limits from state to state can vary greatly, too. For example, a person in California can possess up to eight useable ounces, six mature plants, and 12 immature plants, whereas in Oregon, the possession limit is 24 usable ounces and 24 plants (six mature, 18 immature). Even in California, regulations vary between counties as to how much marijuana can be grown for prescribed medical use, and when and how that marijuana is grown.