Although I do agree marijuana should be legalized in some way, shape or form... I do not agree that it should be readily available for everyone. In your post you are mentioning youths.. Now I don't believe it should be available to them.
If it were to get legalized it should go with the same guidelines that currently govern alcohol and tobacco. You must be over 19 to purchase it (18 in some provinces). Otherwise it's only going to cause all sorts of other acedemic problems with the youths in school.
Quite honestly, although I use it for medicinal purposes myself on occasion, I don't think there would be a case, albeit rare, that a youth would have the need for marijuana. If it were readily available to the youths, moreso than it is now, it would only cause problems with youths being 'stoned', as it were, in classrooms and zoning out and not really learning a thing.
There need to be guidelines when it is legalized, note how I said when and not if, and they need to be sensible and enforcable much the same vendors are already fined when they sell alcohol or tobacco to minors.
Now Im not saying this is a solution by any means, if youths want to smoke it they will, this has always been the case and nothing will stop that. All Im saying that if it is readily available to them without any legal age requirement educational levels in Canada would get pooched from everyone being high and zoning out in school.
The schools already enforce a no-drug policy that I am aware of, this may cause more of a detrimental effect on schooling and we might have record numbers of expulsions in schools. Then again, what do I know?