Special police flashlights have been in use in certain college towns and other locations that can detect alcohol on a person's breath if held near their face. These flashlights could be used in a traffic stop in which the police officer thinks a person may be driving under the influence of alcohol.
The devices look like regular flashlights but they detect alcohol vapors and have indicator lights that tell the officer whether the person may have been drinking lightly, moderately or heavily.
These flashlights are not entirely precise, and officers say that they wouldn't be used as the sole evidence to convict someone of a DUI. Officers will, however, definitely use them to decide whether to continue to test someone for DUI, such as by subjecting a driver to field sobriety tests or Breathalyzer tests.
A driver pulled over by a police officer on suspicion of DUI or any other reason would not know that a police officer was using the DUI flashlight device to try to determine whether there was evidence of a DUI.
According to one recent article about a federally-funded study of the use of the devices on a college campus, the devices led to an increase in the amount of people who were suspected of driving under the influence at DUI checkpoints and given further testing.
Before the flashlights, the number of people who were identified as having a blood-alcohol concentration over the legal limit was 55 percent, and after the flashlights were put to use, that percentage rose to 71. The flashlights are thought to be able to help officers more readily detect underage DUI cases since a person under 21 does not have to be intoxicated to be arrested for DUI.
Source: StateCollege.com, "Alcohol-Detecting Flashlights Introduced in State College DUI Enforcement," Adam Smeltz, Sept. 27, 2011