Marijuana Laws are based on racist and other ignorance policy.
The First Laws against Marijuana were created to discriminate against Black people and Mexicans
1900 - 1969
1970 - 1999
2000 - Present
Sources
http://facultypages.morris.umn.edu/~ratliffj/psy1081/drug_laws.htm
http://www.druglibrary.org/schaffer/history/drug_law_timeline.htm
http://en.wikipedia.org/wiki/Prohibition_of_drugs
http://www.time.com/time/nation/article/0,8599,1888864,00.html
http://www.cedro-uva.org/lib/harrison.cannabis.05.html