SB 499 - This act renames the offense of driving with excessive blood alcohol content to the offense of driving with prohibited blood alcohol or drug content. In addition to current provisions about driving with certain levels of blood alcohol content, a person is guilty of this offense who operates a vehicle while any amount of controlled substance is present in the person, as measured in the person's bodily fluids. The presence of a controlled substance in a person's bodily fluids after the person was operating a motor vehicle is presumed to show the presence of such substance at the time the person was operating the vehicle. When a person is charged with this offense on the allegation that a controlled substance was present in the person while operating a vehicle, that person may assert the affirmative defense that the controlled substance present in that person's body was prescribed for that person and taken in accordance with medical directions. JOHN GRANA