extrapolation. even though i don t take your blood immediately, arthel, i will know what your blood-alcohol content is at later time because all of us have elimination rate. alcohol eliminates out of our body at a certain rate. if i know the elimination rate and two hours, three hours later when the blood is taken, i know. the last point, the last point is this. blood is not the only measure to establish a drunk driving case. there are numerous tests that can be done. stand on one leg for 30 seconds, are you drunk? you touch your nose, are you drunk? arthel: let me give rebecca the last word on this one, joey. the issue doctors need to know your elimination rate, and if they do not they can not determine when the blood-alcohol level was at what level at what time. arthel: many factors come into play. too way and difficult there after the fact. the argument really is, someone driving drunk they could kill someone. it is not that invasive . arthel: everybody agrees drunk driving is