There driving stats are funny.   Being stoned makes you a worse driver and a terrible navigator.    The user almost always know that and that's why they are going to slow, normal traffic can make you very edgy.    That helps avoid serious accidents.     But you also get the other side when the drive drops his munchie in on the  floor, or makes a crazy turn because he had forgotten where he was headed and was enjoying watching the rain drop work down his windshield.    The stoned driver is seldom aggressive, often trying to be a 'good' and conscious of her potential to mess up and hurt somebody.  The angry driver is a much bigger risk.  Fights break out with drunks, I've never seen  a serious fight with a stoned person - unless they are drinking heavily as well.