He has been running wild for months and our support group for troubled teens is big on letting them learn from experience.
Unfortunately that experience can be overdose and death.
A parent does have control over a child of 15 and if you can't control him then a court/judge/police must.
It would appear the only communication is him doing what he wants when he wants. What are/has been his consequences when he disrespects you as a parent? When he doesn't follow house rules? And where is he getting the money to buy his drugs?