America has 25% of the world’s incarcerated population, and a higher percentage of its black population in prison than South Africa did at the height of apartheid.

This is why they will not legalize drugs; it's too profitable. They fear that medical marijuana will start a trend towards utilizing other drugs for medicinal purposes. It was only in the early 20th century that opium and cocaine were made illegal. Up to that time one could purchase them in their local apothacary.