Xiuming (Audrey) Dong of Syracuse University, whom I met at the National Tax Association conference in Tampa, has allowed me to post her paper on workplace externalities of marijuana legalization, which contains this: “My estimates suggest workplace injury rate is approximately 5%-20% higher for treated relative to control counties post-[recreational marijuana legalization] RML. It also indicates that RML increases work injury costs [in Oregon] roughly by $7 to $34 million (or $5 to $24 per capita) per year.”
So Ms. Dong’s paper calculates negative externalities, but she is now working on a project whose preliminary results show that legalization may reduce disability insurance claims. Still, that is an on-going project. Myself, I wonder about any results based on movement from illegality to legality, for reasons the paper mentions, and especially because the change in consumption is very gradual, since the black market existed before legalization, and because legalization takes root slowly.
As my friends in social science (unlike my friends in tax policy) often say, more research is needed.