Cannabis, commonly known as marijuana, pot, reefer, and grass, is a preparation of the cannabis plant that is used as a psychoactive drug or medicine.

The earliest recorded uses date from the 3rd millennium BC.  Despite its long history of use as a natural medicine, since the early 20th century cannabis has been subject to legal restrictions. Possession, use, and sale of cannabis preparations containing psychoactive cannabinoids are currently illegal in many parts of the world.

Despite the U.S. government’s prohibition of the plant, scientists have continued to study it, and people have continued to use it for both recreational and medicinal purposes.

So far, scientific study of cannabis has identified more than 80 unique, biologically active cannabinoids. A recent meta-analysis of these compounds shows well over a dozen therapeutic properties attributable to cannabinoids, including neuroprotective, anti-cancer, anti-bacterial, and anti-diabetic properties.

A review of several hundred papers assessing cannabis’s therapeutic properties is available on the National Organization for the...