Just to elaborate on that, in my view the argument comes down to two basic issues.
Firstly, can adults do what they want with their bodies, or does the government have a role in regulating such matters.
Secondly, and if the answer to the first question is no and yes, respectively, then what principles do we use to determine how government should regulate.
I'm not really on the second question, as my view is that adults should be able to take what they want, and government's role should be limited to an information one. However, if other people disagree then my view on the second question is that the principles used should be, at the very least, rational. I don't think that's a controversial opinion.
For example, the current position in the US is that many states have now legalised weed for both medical and recreational use, yet it is still legally scheduled as a drug that has "no currently accepted medical use." Ecstasy seems to be less harmful than tobacco or alcohol (and also appears to work
in treating PTSD) yet it is illegal and they are not. Ketamine has come to light as a
treatment for depression, yet it is still illegal because some people like taking it for recreation. Heroin is not that different to morphine, which is prescribed for millions every day, yet one is trusted and respected and the other one is for scumbags. That makes no sense.