Forget the "walk-and-turn" field sobriety test; researchers have developed a laser that can detect drunk drivers remotely. A team at Warsaw's Military University of Technology shined a laser beam through a moving vehicle, along with a reflective mirror that bounced back to a detector, to pick up alcohol vapors. With a system to simulate a drunk driver's breath, the researchers were able to detect blood alcohol concentrations higher than 0.1 percent. (In the US, a concentration of 0.08 or greater is considered illegal.) With a real drunk person, though, the lasers-and-mirrors setup could likely detect even lower levels.
The system isn't perfect; both driving with the windows open and driving with the AC on were able to throw off the alcohol vapor-detection system. In these cases, the system would alert police officers and indicate that the cars should be pulled over and checked. The next step will be making the system more compact, as well as investigating other scenarios that can affect its accuracy. If law enforcement adopt this setup, though, we could see fewer cars pulled over -- and, most importantly, increased efficacy in catching those who are driving under the influence.