http://money.cnn.com/pf/features/lists/taxes_marijuana/table.html

These numbers seem low to me. I live in California and I've heard that marijuana is the state's largest cash crop at over $8 billion in total market size. A normal statutory business tax rate on just selling cannabis for smoking (not including all the money from sales hemp for paper, clothes, food, fuel, most things that use trees) would be 38%, but let's be conservative and say 20% effective. Take a low ball $5 billion estimate of the CA cannabis industry and multiple that by 20% and you get $1 billion dollars of taxes. Reduce government spending on cannabis prohibition, replace some of it for education and rehab from hard drugs and there is a net benefit of more than $1 billion dollars...plus the creation of a nice private industry selling its somkeable product through regulated establishments (e.g. alcohol).

I don't know if CNN was just quoting the federal taxes at $100 million but that is wayyyy to low. Of course the article is from 2005...