Legalizing marijuana in your given state, province or country has the additional benefit of being able to place a tax on the commercial sale of a drug normally sold on the black market: since they've passed legalization bills, California, Washington and Colorado have all generated more than $1 billion. This is a sum of money too small to ignore (although not necessarily in contrast to the overall budget of these states).
Where should states/nations invest this revenue? Some ideas proposed include directing funding towards awareness campaigns, public schools, or human services. Since the United States is currently in an opioid epidemic, it also seems wise to consider forwarding resources to address this public health crisis concerning more dangerous drugs. Given the money comes from vending citizens an unhealthy substance, what's the most ethical solution?
The tax money could be useful if invested in public/merit goods, such as education and healthcare. However, it is very difficult to track where this tax money is used, and is extremely unique to the country/circumstance. Therefore, I don't think the "use" of the tax money, or the potential benefit to society, is a sufficient argument in itself to justify the legalization of marijuana.
I think that this is a really important issue. While, money generated from marijuana sales should go towards schools, the specifics should be looked at closely. Many low income people, usually black or hispanic, are disproportionally charged with charges for possessing or selling marijuana. If we are not careful, the money generated from weed sales could be used to further marginalize those groups. Education is the largest arbiter of socioeconomic justice. This new source of income should lift up all schools, not just the ones in "nice" neighborhoods.
I think that the best place to direct the money from marijuana taxation is in public schools and public service. This allows each town or city to manage it directly and better their towns or cities overall. If there is more money provided for public schooling, kids can be better educated on what exactly marijuana is, effects, and dangers to make more informed, smarter decisions in the future. The tax can also have a positive effect on communities in the form of homeless shelters and other public works to help get the homeless off the streets and help communities become cleaner and safer.
I think at least a fraction of the money should be spent on constructive public advertising to ensure safe and healthy use. As of today, most taxes from cigarettes are used to reduce state and federal budget debts. However, according to the American Lung Association, some activists are petitioning for the redirection of tobacco taxes to youth education and quitting programs. Though it may be unreasonable to ask the government to invest all tax money into public health campaigns, at least some revenue should be used to educate the public on the consequences of abuse.