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 Warsaw's 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 occupant's 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. US states have a blood alcohol limit of 0.08 percent to qualify as driving drunk.

Results can be altered by drunk passengers

There are some caveats: results can be altered by a range of factors including other drunk passengers in the same car, open windows, or air conditioning. The device won't be able to detect every inebriated driver — as Popular Science points out, the US National Transportation Safety Board classifies humans as "drunk" with 0.05 percent blood alcohol level — but the researchers say that their creation will both decrease the number of cars police check, and increase efficacy of stopping drunken drivers.