Until its prohibition in 1937, extract of Cannabis sativa (marijuana) was one of the top three most prescribed medicines in the US. When it became illegal, its use as a medicine became restricted. Despite these regulations, research on the medical use of marijuana continued.
In recent years, when some states decided to legalize smoked marijuana for certain patients, medical marijuana became a subject of contentious debate. Should patients be allowed to grow their own plants? Might medical use inevitably lead to recreational use?