According to the U.S. Department of Justice's Bureau of Justice Statistics (BJS), "Drug Use and Dependence, State and Federal Prisoners, 2004," 12.7 percent of state inmates and 12.4 percent of federal inmates incarcerated for drug violations are serving time for marijuana offenses. This turns into it costing U.S. taxpayers more than $1 billion a year to keep pot heads locked up. That can be turned into 1 out of 8 American drug prisoners are locked up for marijuana.

Paul Armentado (AlterNet) reports that according to the most recent figures available from the FBI, police arrested an estimated 786,545 people on marijuana charges in 2005 -- more than twice the number of Americans arrested just 12 years ago. Among those arrested, about 88 percent -- some 696,074 Americans -- were charged with possession only. The remaining 90,471 individuals were charged with "sale/manufacture," a category that includes all cultivation offenses, even those where the marijuana was being grown for personal or medical use. These totals are the highest ever recorded by the FBI, and make up 42.6 percent of all drug arrests in the United States.

Marijuana isn't a harmless substance, and those who argue for a change in the drug's legal status do not claim it to be. However, pot's relative risks to the user and society are arguably fewer than those of alcohol and tobacco, and they do not warrant the expenses associated with targeting, arresting and prosecuting hundreds of thousands of Americans every year.