[vikramkr]

The context of that comment is a parent comment asking about medical self experimentation. You're also not allowed to administer scheduled substances to yourself in many jurisdictions and plenty of other things like that but that's not what I was replying to.

[cogman10]

You actually are allow to administer all sorts of scheduled substances to yourself. You aren't allowed to posses those substances.

The laws that do target someone for being in an altered mental state are mostly about being that way in public.