A group of scientists in Poland have invented a laser-based device that can detect alcohol vapor inside a passing car (see below).  The device works by detecting subtle changes in the laser beam as it passes through the alcohol vapor.  However, as the Huffington Post notes, one of the problems with this device is that it cannot differentiate between the alcohol vapor of the driver and the passenger.  Perhaps with a few modifications – specifically the ability to identify the driver (and not passengers) as intoxicated, this could be an effective deterrent for drunk drivers. What do all of you think?