I have addressed this issue in the past. Speaking as a medical doctor, a law enforcement officer, and a military officer, I will again state that the control of potentially behavior-altering substances with medical uses is a very dangerous slope. As a doctor I do not want to deny anyone the right to alleviate pain or prolong life. As a law enforcement officer I consider it at best ineffective and at worst counterproductive to investigate what is essentially a victimless crime; it makes approximately as much sense as punishing people who attempt to commit suicide. And as a military officer I disapprove of wasting resources by arresting or imprisoning the sick. And finally, as an ideological libertarian, I believe that people have the right to ingest any and all substances for any and all reasons.