Driver will sit in the car and will press the START BUTTON By the time HE/SHE will push the start button INFRA-RED SENSOR will start working & will measure ALCOHOL in perspiration through contact with the SKIN As alcohol begins to arrive at skin surface in just 10 minutes,hence sensor can easily detect it So it will be good for all,If all cars will be equipped with device that wont let the car to START,If driver will be drunk SENSORS in this product are not bulky,and are therefore SMALLER in size The system is not POLICE DEPENDENT If you are drunk then any of your family member can drive & even it will protect your car from UNAUTHORIZED ACCESS