InLight Solutions, which develops products to test blood sugar levels without needles, has developed a
similar system to measure blood alcohol content. This 'alcoholic arm scanner' uses an infrared beam of light that scans
a suspect's arm. After going around 5 millimeters into the skin, the beam is reflected back to the device, which then
compares the results. The reflected beam changes depending on the suspect's alcohol level, giving a BAC readout.
(Thanks, zeroblogger, raffi, and Greg!)
[Source: New Scientist via RealTechnews via Gadget Review]