A humorous look at revenue from taxing marijuana is “Dude, Should Marijuana Be Legalized and Taxed?,” by Howard Gleckman, http://taxvox.taxpolicycenter.org/2012/12/06/dude-should-marijuana-be-legalized-and-taxed/
But the $9 billion it reports sounds a little low. A strong revenue regime – after-tax prices unchanged, with government taking the 80 percent Europeans get from cigarettes, might see 30 million consumers spending $1,000 each a year. That’s $24 billion in tax. That’s coincidentally in line with $25+ billion from the official WA estimate extrapolated. That WA estimate is too high, I think, but WA’s tax plan is weak: The initiative process puts the marijuana community in charge of writing the tax laws. They can hardly be expected to lead the charge to tax themselves.
Even $500 per consumer per year could send $400 to government — $12 billion total.
That last number seems conservative, but who knows? Maybe the market in dollar terms will be small. John Prine said that his “illegal smile . . . don’t cost very much, and it lasts a long while.”
Maybe some day we’ll find out.
 See page 259, text accompanying footnote 34, of “Gangs, Ganjapreneurs, or Government: Marijuana Revenue up for Grabs,” State Tax Notes, Volume 66, Number 4, pages 255-269 (October 22, 2012), online at http://ssrn.com/abstract=2165864 and https://newtax.files.wordpress.com/2012/10/gangs-ganjapreneurs-or-government-marijuana-revenue-up-for-grabs.pdf.