For anyone who thinks a heavily regulated legal market is the panacea for the OD crisis. 

http://www.theglobeandmail.com/news/british-columbia/prescription-opioid-use-grew-in-bc-ahead-of-overdose-crisis-study/article33436771/?reqid=b8e0a486-c2f7-48db-9be0-bc70eff6a902

The legal marker created a massive black market for opioids. Thousands of people die per year across Canada from prescription opioids and hundreds of thousands develop addictions. When they can't get their fix form legal sources what happens next?  You guessed it.  

Legalization may help in the most extreme cases but not much more. It will not stop the black market. It may even grow the black market like you've seen with Oxy's and Perc's. When you're dealing with something so addictive and  lethal there are no easy answers.