Polish researchers have developed a laser that can be fired at cars to find out if their drivers are drunk. The device, detailed in a study published by scientists at Warsaws Military University of Technology, can detect alcohol vapor inside moving vehicles by using special curved mirrors and beams of light. The device works by shining a laser through a car from the side of the road, before the beam of light bounces back off a mirror and into a detector, informing the researchers of the occupants blood alcohol level. The study says the device was able to detect blood alcohol concentrations of as low as 0.1 percent in tests using a system that simulated the breathing of a drunk driver, but with human targets, the scientists say it could be capable of detecting lower concentrations.