Unless your kids are removed from society, then its also a societal issue. I don't think anyone on the spectrum of this debate could argue that if the government had a way of effectively getting through to youth about the risks and harms of drugs it would be beneficial for everyone. 

You might be a great parent and be able to communicate with your teenager effectively on this topic - but if none of your teenager's friends parents are doing the same then you will be competing with a peer group that carries [possibly] more influence and authority than you as a parent...

Unless you want to home school your kids, then whatever I guess...