Legal/illegal, crim/decrim. Both have the good aspects and bad, but like res said most importantly people need to be educated cause when it comes down to it, you make your own bed. Whether you choose to smoke, use other drugs or whatever.
Shit I am studying to be a primary school teacher and I had to sit through some fuckers lesson on how marijuana is a bad drug and it's bad for you so just don't do it. Kids don't listen to that shit and then go ok I won't. They go oh wow drugs I wonder give me some and I will find out for myself.
My mum was a counsellor, and we lived with a reggae band for a while and saw people completely fucked on drugs a lot as a child. My mum gave me some sort of scientific pamphlets to educate me a little on what drugs where and what they did to your body but never once did she say don't do them or their bad. Nothing was hidden or exagerated.
As a teenager I experimented and was able to tald to my mum about stuff. I saw many of my friends fuck up badly because of drugs and they had no one to turn to, because they felt ashamed and knew their parents would freak. To be exact three of them died, 2 suicides one on pot and the other drunk and 1 o.d on smack. One guy started on pot, moved to speed, then smack and now he's in jail.
The whole point of this long story is that the one thing most of these people had in common is that they were not given real life education just stuff out of books or out of their parents mouths. If using drugs was out in the open then society would be able to better deal with the problems that come with (such as addictions and mental disorders).

Hope this all makes sense. I just had to get it out.