HGN

It's amazing how telling this test is of whether someone is under the influence or not.

HGN stands for Horizontal Gase Nystagmus. It is a test used by law enforcement to determine if someone is under the influence of alcohol and/or drugs. It's part of the Standardized Field Sobriety Tests (SFST). You know that famous test you always see conducted? The 9-step walk-and-turn? HGN is the test where the cop is using their finger or a pen to check the subject's eyes.

What the cop is looking for is a detection of nystagmus from either eye. Nystagmus is defined as involuntary jerking of the eyes. There are medical conditions in which a person might have a natural nystagmus. However, nystagmus is mainly caused by a depressant (ex. alcohol) which relaxes the muscles behind the eye, which cause these involuntary jerking movements.

There are "6 clues" to this test. I was taught, if you see all 6 clues, it's an automatic arrest, regardless of what the other tests prove. Easier said in a classroom, then done in real life, but it's true. Last night I had that situation. The person did ok on all the other tests, but failed HGN miserably. I ended up arresting him, and he blew a 0.102% BrAC (legal limit for adults is 0.08%, limit for minors (under 21) is 0.02%, he was a minor). So, I did the right thing. It just is mind boggling how accurate the HGN test is. However, it is not admissable in court as of yet. It is only admissable as probable cause for an arrest.

So, I've had my first DUI on mids, and it was only my second shift! Go me! (And Kirt, who was my backing officer. He helped me out a ton).