Certainly, I think your addiction and eventual recovery will be an uncommon perspective that will add diversity to any law school. It probably won't carry as much weight if you were a rich suburban kid who's friends coaxed you into trying cocaine (a la Soderberg's Traffic), but I still think it's a refreshing story they probably haven't heard very often.
While not exactly the same subject, one of the absolute best PS' I've ever read was about a person who almost became a drug dealer to deal with his financial problems. So yes, don't be afraid of venturing onto a somewhat controversial subject. More than likely, you'll be glad you took the risk.