Biggest problem in prosecuting under the influence of pot is the amount of time it stays in urine, or bodily fluids, for occasional users that is up to 30 days. So if John Pot head takes a vacation and while in his cottage he burns one every evening for a week while there, not leaving, just chilling and buzzing, then a week later on his way back to work some idiot crossed Buford (kill zone) hwy.in Chambodia and kills an illegal, he gets all the required testing, alcohol and drugs and gets a positive hit on Pot, boom, he is charged with driving under the influence. This is such BS, its not that he is under the influence its that the stuff hangs around, not affecting or impairing the brain or anything else, not even the impulse to eat a box of Twinkies, therein lies a huge problem. In the world of drug testing especially the so called tolerance level for 2nd hand smoke, which could also be a huge problem, if John non pot head rides with John Pot head to say pick up a car 2 hours away and during that trip John pot head burns 3 or 4 potent doobies, and the next day John non pot head gets hurt at work and gets tested and goes over that tolerance level he looses his livelihood and he and his family suffer for something he in fact didn't do himself. I know this to be a fact had a friend that never smoked so much as a rabbit tobacco hand rolled as a kid and rode with a bud to pick up a car in south Ga and got fired cause he failed the test, barley, but failed due to nothing more than second hand smoke in a car with the windows rolled up due to dead of winter.