I enjoyed this dizzying attempt by Mark Kleiman to quantify the actual potential revenue that could be generated by legalizing marijuana in California. It's a fun exercise, but you can only get so far down this path before becoming overwhelmed by hypotheticals. For example, Kleiman bases his calculations on the estimated population of marijuana users in the state (I'm sure some people who don't live in California would buy pot there).

There are many things we can't account for, such as the percentage of users who develop a sudden interest in gardening once marijuana becomes legal to cultivate for personal use. Regardless, the bottom line is that legalizing and taxing marijuana will generate plenty of taxable income. Of course it will. There are ways in which it won't pay out the way we'd hope, but also other ways in which it will create unexpected financial benefits. Not ruining people's lives for possessing it is a huge bonus by itself. Imagine trying to calculate the economic harm collectively suffered by people who've been arrested for small amounts of pot and couldn’t get jobs, etc.

Leaving aside all the other powerful reasons for changing marijuana laws, I'm sure the people of California could devise a marijuana policy that makes vastly more economic sense than the current one.