If you are far enough away and they are standing still enough to throw a knife at them, you are likely not going to fair very well under any sort of examination in court. You should have walked away first.
If they have a gun, they would have already shot you. If they haven't yet, when you chuck a knife at them, they will. When they have the one story to tell, they will also be the one defending themselves. Win for them.
As already mentioned too, if you miss or it hits handle first, you just tossed them a knife "Oh hai, thanks for the knife, I forgot mine home.".
The idea of throwing a knife at someone is pretty absurd if you just stop and think about it.
Throwing a folder will just break it, even if just doing it for fun.