Prohibition doesn't work, we could tax it, it would reduce violence, prohibition prevents a boom in pot usage, marijuana is unhealthy/healthy... Some of the arguments in the debate surrounding the decriminalization of Marijuana.
In a country where Marijuana is more or less legal in small amounts, the boom concern does not seem to have materialized. That having been said, the people at the freakonomics blog have compiled an interesting group of people to contribute their opinions on the matter. Read it HERE.
One part I thought that was particularly interesting...
"...a graduating economics major at Brown named Max Chaiken, ... finds that “a legally taxed and regulated marijuana market could generate upwards of $200 billion annually in excise tax revenues for the federal government … [which] would be enough to fund Medicaid.”"