How Do The Police Administer The HGN Test? (Continued)

How Do The Police Administer The HGN Test? (Continued)

Police use the HGN as part of their arsenal to investigate DWIs. They are used throughout the nation and the test is very heavily promulgated by the National Highway Traffic Safety Administration. The HGN is specifically designed to only test that nystagmus in a horizontal gaze (side-to-side) as opposed to a vertical gaze (up-and-down). 

The officer will place a pen, tip of the pin, or penlight about twelve to fifteen inches from the subjects face. The instrument will be slightly above eye level (which according to NHTSA makes nystagmus easier to see). Again, the officer will tell the subject to keep his or her head still, as he moves the instrument to the left and right--across the entire field of vision. The purpose of this is to see if the person's eyes are tracking normally. The officer will then check to see if the person has equal pupil size. 

The reason for these checks is to determine if there is some sort of medical condition that will prevent the administration of the HGN. These conditions might include blindness, medical disorder, or an injury.

Stay tuned as we continue to examine the HGN test used to investigate people suspected of DWI. If you have been charged with DWI, contact a Plano criminal defense lawyer today.
Categories: