DUI kNOw One-Leg Stand is similar to a field test that law enforcement can use to determine a DUI. It is like nothing else on the market. It uses the orientation sensors of your phone to see if you can stand on one leg. The sensors are activated after you put the phone in your front pants pocket and stand on one leg. Your phone will know if you would probably fail a law enforcement administered one-leg stand DUI test. The app knows if you put a leg down, wobble, hop, walk, or fall.