While it's still controversial, medical marijuana is edging toward normality.

Forty states (and the District of Columbia) now have some form of law on the books that allow the drug to be used for a variety of ailments, and sales are soaring— reaching $5.4 billion in 2015.

That doesn't mean it's widely available in all of those states, of course.

Some, like Alabama and South Carolina, have extremely strict circumstances under which cannabidiol products can be prescribed, and still forbid the production and distribution of the drug. And even in states where it's easier to come by, there are differences in how it's handled.

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Chris Morris ~ CNBC.com ~