I would like to read "Equilibrium and Optimality in Regulation of Vice", wherein we rigorously treat the trade-offs between black markets, legalization, regulation, state owned distribution, of goods and serviced related to vice.
For instance, I think the state owned lottery shouldn't exist. But, if lottery is an addictive drug to the poor, maybe it will happen anyway ( and cause more harm if made completely illegal ), so as long as this state-run gambling is fed exclusively back into programs that help gambling addicts, its better than a black market ( though I still wish they wouldn't put up the billboard advertisements, these seem quite wrong ). Basically, try to formalize and generalize all the aspects of debate over drugs/gambling/prostitution/gluttony/(and can we extend it to sloth as well? wouldn't that be something). And by formalize I mean that I want to see some equations that are predictive.
I'd like to think about this more, so I'm noting it here and will try to get back to it later. There is probably already substantial work in this field, looks like it would be fun.