The Science of Marijuana, 3rd Edition is directed at a public interested in knowing more about cannabis, how it works, and what the hazards associated with its use may be. In terms of cannabis as a medicine, it is now sanctioned by a majority of US States, with approved medical indications that often go beyond what is really known scientifically about the effectiveness of cannabis treatment. Some countries and US States have approved full legalization of cannabis for adults; the regulations needed to control such legal use are still being worked out. The pros and cons of cannabis legalization are reviewed. There have been big changes in the public perception of cannabis, and increased support for legalization. The book comes at a timely moment in this debate.