"One problem is that sometimes you get into what I think of as an illegality–logic loop. This is an example of a conversation I've had many times with many people, some of them politicians: MP "You can't compare harms from a legal activity with an illegal one." Professor Nutt "Why not?" MP "Because one's illegal." Professor Nutt "Why is it illegal?" MP "Because it's harmful." Professor Nutt "Don't we need to compare harms to determine if it should be illegal?" MP "You can't compare harms from a legal activity with an illegal one." I have been surprised how difficult this concept is to get across to some people, whether they are politicians, fellow scientists or members of the general public." - Mare from Bookmarklet