IMO it should be fully legalized and taxed. Not only would it save a fortune on policing, court costs and keeping people in jail, but the government would be able to make money from it in the same way they do with tobbacco and alcohol. It does have its drawbacks as in it makes people lazy and can cause paranoia for people that overdo it, but in general its far less harmful smoking and drinking. Its also less addictive, which tends to be the main factor used in the classification of drugs. I think criminalizing it is unfair as people that smoke green generally arent arent causing problems for other people, so it should be a matter of personal choice.
