Let's clarify your statement. I am not PRO-DRUG. I am PRO-RIGHTS based upon the Constitution, not just some snooty interpretation of it.
Your founding fathers repeated a statement on a number of occasions saying the Constitution was only intended for a moral people. You are saying you are pro-rights, but you are talking about adding new rights for a society that has rejected the idea of both shame and responsibility. And any legalisation of narcotics will not work unless taking drugs is considered deeply shameful without the force of law (and not "cool" like many young kids will see it), and people are willing to take responsibility for their actions. And in this day and age, if LSD was legalised, people would sue the manufacturer for any bad trips they took.
Be pro-responsibility and pro-morality before we even start discussing drug legalisation. For it to be anywhere outside of creating chaos, you'd have to reimpose Victorian morals (the late 19th century was the last time recreational drugs were totally legal), and somehow I doubt you closet lefty Libertarians would like that.
Ivan