Consumers should exercise extreme caution when using any app on a mobile computer to determine whether they are fit to drive. For instance, in late 2011, a company called Breathaleyes began marketing an app on the iTunes store that is to be used to determine whether a person is exhibiting alcohol induced horizontal gaze nystagmus. The HGN is one of the three standardized tests developed by the National Highway Traffic Safety Administration to assist officers in determining whether a person’s blood alcohol level exceeds the legal limit.
It should be noted that the proper examination and analysis of whether somebody exhibits sufficient signs (clues) of alcohol induced nystagmus is complicated and should not be used to make a determination about whether someone is sober enough to drive.