New App Says You're Too Drunk To Drive

A new app for the iPhone called BreathalEyes, detects involuntary eye movement to let potential drunk drivers know when they've had a few too many.
By using the iPhone's camera, the app records a person's Horizontal Gaze Nystagmus (HGN), a condition where the eye involuntarily jerks and twitches when a person looks to their right or left while holding their gaze. HGN can be caused by alcohol consumption and those suffering from it are unaware it's happening. This is why officers commonly check for HGN during field sobriety tests.
Legally intended for "entertainment purposes only," BreathalEyes was tested alongside a breathalyzer and found to have an effective range of 0.02 -- 0.18 percent, with (+/-) .02 percent accuracy of blood alcohol content (BAC) levels.