I saw the sign on the back of the van and I understood that I was to "Stay Back." I just didn't understand why. Not that I was tempted to disobey. I wondered, "Did they forget to lock the back door? Will a prisoner throw the door open and scratch my car's bumper?" I suppose the sign means that drivers should give the sheriff lots of room to get the prisoners in and out of the van. Perhaps the warning could be better phrased, though.