Crarg, The difference is that Alcohol and Tobacco are not illicit.
They don't draw children into a 'cool scene'inhabited by criminals. They are not a demonstration that breaking the law is OK.
If marijana was regulated like Tobacco and Alcohol it wouldn't be the easy path to hard drugs. However society has drawn a line in the sand about what is legal.
My point is either we should enforce the line vigorously or remove it.
