I'm not sure I entirely agree with this. Your judgment is impaired, which also means that your judgment to judge whether or not your judgment is impaired is impaired. There are some drugs that are so strong, that once taken, the recipient will do anything to get more of it -- including become a non-productive member of society, nee, a destructive member of society -- you sure you want to say that people have a right to take that in an uncontrolled manner? I'm not sure I'd go that far.