Roe v. Wade and Medical Marijuana
Roe v. Wade essentially states that one has a right of medical privacy that is so strong that the question of personhood doesn't matter because the right of medical privacy is sufficiently strong as to supersede any rights granted by the achievement of personhood. The controlling opinion issued by the Supreme Court noted that neither medical science nor they could determine if a fetus/blastocyst/et al had achieved personhood, but that the right of medical privacy allows for an abortion whether or not an answer could be reached on that. That means that the question of personhood is irrelevant.
Whether or not you agree with that idea, the question I pose to you now follows it quite naturally. If that is the case, then why don't you have a right to medical privacy that allows your doctor to prescribe heroin, amphetamines, quaaludes, or any other drug they and you both see fit for you to use? Whether it is for depression, joint pain, cancer, or recreational use, the right to medical privacy should allow this to be a transaction that does not include the federal government.