@Liz223
So the police in your area have so little to do that they have time to chase someone downthe following day, because one person has alleged that someone else was stoned the previous night?? Wow. (Did you drug test him? Did you see him smoking something that you had proof to be an illegal substance? How do you know for sure that he hadn't just been around others who had been smoking, and the smell had simply lingered on his clothes?)
If you were so discombobulated about the potential of the guest running someone over and killing them in his van, why on earth would you send him on his way, for that possibility to occur? Surely you should have got back on the phone to the police and insisted they come and arrest him immediately, before catastrophe could strike.
And "if he rapes another guest at the house". Seriously?? Could you point us to any study/statistics/research that correlates the smoking of weed with the increased risk of the partaker becoming a rapist?
"Maybe you are someone who takes drugs allegedly so you see that is ok"
Quite frankly, even if I were, it would be absolutely none of your business. You may describe yourself as a "moral host guardian", but you're certainly not my moral guardian, so we'll leave it at that, and I'll refrain from making hypothetical, presumptuous judgements on your character, as you seem prone to doing on others.