The LP platform is NO illegal drugs, period. No age criteria is mentioned. It is fundamentally against LP principles to set an arbitrary GOVERNMENT SANTIONED age limit on activities that do not harm others.
Otherwise, your parents/guardian is still responsible for making those types of decisions for you are are directly responsible for the consequences of your actions.
As for what age my children will be getting my permission to engage in such activities? They'll be adults before they get my permission. Isn't that what a PARENT is supposed to do? When did such things become the GOVERNMENTS job? Do you approve of a Nanny State government?
I think the American people could not handle the responsibility of such a system. I really think there are some Americans who could not handle the freedoms the Constitution theoretically allows. Their heads would implode, or they would be furious that others are doing what they consider to be wrong, or they would go the other way and take it to the extreme and become irresponsible.
Well minors should allways be considered in the law, they don't even have constituional rights and their parents are legaly responsible for them.