Legalize possession of personal quantities of all drugs. Highly regulate the sale and production of drugs -- limiting sale to personal possession amounts, tracking sales to prevent store hopping. Highly regulate where drugs can be used -- not in public, on the streets. Use tax money strictly for rehab treatment, enforcing regulation, drug research, building safe injection houses, etc. You can't just decriminalize drugs, you have to control the production and sale. This ensures quality control and gives social workers direct access to drug users, not to mention removing the black market and the hell that comes with it.