This would be manged under the "CaptainCourtesy Ending The War On Drugs Plan". Some of you have read about this before. I will not go into the entirety of the plan, just the basics:
Current "illegal" drugs are legalized. All violations that would pertain to alcohol, apply, such as driving under the influence. Employers, of course, have the right to fire anyone who "works under the influence". All drugs are taxed by the government... similar to cigarettes. All tax monies go into a fund for substance abuse treatment. One of the flaws with Scott's plan, and one of the problems with addicts becoming clean is the cost of substance abuse treatment. A 30 day stay in a facility can cost upwards of $25,000... sometimes to start. If an addict wants treatment, they receive an evaluation to determine whether they would qualify under the government subsidy. Things like history (have they had failed treatment attempts), motivation, and perhaps their own financial ability would be assessed. If they qualify, the substance abuse fund will cover their treatment. Under this welfare policy, since these folks would be receive government money because of need, either they would agree to attend treatment (again, covered by the fund) or their benefit would be eliminated. If they have children, their children would have a "designate" who would manage their money.
This helps resolve two issues: the war on drugs and the problem with substance abuse.