Say no more, that's the key to the whole question. Marijuana would already be legal if not for the fact that hundreds of thousands of cops, prison guards, bureaucrats, judges and lawyers derive their livelihood from keeping it illegal. Jobs for the boys.
-ccm
That Harvard study got its marijuana numbers as a percentage of the police department budget.
For example, if the budget was $10 million and the police department spent 10% of their time arresting marijuana users and dealers, then the department would "save" $1 million if marijuana was legal.
Do you really believe that their next year's budget request would be $9 million? Do you think the department would be "downsized"?