What is the horizontal gaze nystagmus sobriety test

Mark RollinsDUI


DUI lawyer explains what is Horizontal Gaze Nystagmus sobriety test

This video discusses horizontal gaze nystagmus sobriety test that should be performed by a certified police officer.    That means the officer has taken a certification course regarding horizontal gaze nystagmus sobriety test.  The video discusses how police officers figure out horizontal gaze nystagmus.
Now in order to explain this, the video breaks away and actually shows the view “jerking eyes.”  I want you to think about is the eye movement because this is the typical test where you see the object in the middle and the officer is asking you to follow the object. Now how they make out to determine whether someone is intoxicated is what the eye movement does while it’s going from one direction to the other and that will make the determination whether the officer is going to see whether the person has alcohol in his system.

Presentation of HGN

While conducting the test, the officer looks for six “clues,” three in each eye, that indicate impairment. The officer should record the clues on the HGN Guide. The left eye is checked for the clue, and then the right eye. The clues are:

  • LACK OF SMOOTH PURSUIT – The officer moves the object slowly but steadily from the center of the subject’s face towards the left ear. The left eye should smoothly follow the object, but if the eye exhibits nystagmus, the officer notes the clue. The officer then checks the right eye. (See Appendix B, Picture 2.)
  • DISTINCT NYSTAGMUS AT MAXIMUM DEVIATION – Starting again from the center of the suspect’s face, the officer moves the object toward the left ear, bringing the eye as far over as possible, and holds the object there for four seconds. The officer notes the clue if there is a distinct and sustained nystagmus at this point. The officer holds the object at maximum deviation for at least four seconds to ensure that quick movement of the object did not possibly cause the nystagmus.44 The officer then checks the right eye. This is also referred to as “end-point” nystagmus. (See Appendix B, Picture 3.)
  • ANGLE OF ONSET OF NYSTAGMUS PRIOR TO FORTY-FIVE DEGREES – The officer moves the object at a speed that would take about four seconds for the object to reach the edge of the suspect’s left shoulder. The officer notes this clue if the point or angle at which the eye begins to display nystagmus is before the object reaches forty-five degrees from the center of the suspect’s face. The officer then moves the object towards the suspect’s right shoulder. For safety reasons, law enforcement officers usually use no apparatus to estimate the forty-five degree angle. Generally, forty-five degrees from center is at the point where the object is in front of the tip of the subject’s shoulder.

Getting a DUI Lawyer to Help you

Welcome back ladies and gentleman. I hope that part wasn’t too spooky with the four eyeballs, each going different ways, but what I failed to mention during that part of the presentation was also that the officer is supposed to do that test twice. That means that there would be a total of six times in which they would be able to read those clues. They would only be required to have four of those clues met for them to meet their standards of failing the horizontal gaze nystagmus test. If you fail four of those tests, and the officer sees those clues four times during running that test twice, then they would say that you failed that part of the field test.
What I don’t want you to fear is that there other reasons why you may actually fail those three tests and that needs to be brought out on cross examination as well as cross examining the officer. For instance, you could have conditions such as wind or dust getting into the eyes which would also cause that jerking motion. You could also have distractions that the officer did not realize at the time such as strobe lights, the flashing lights from the officers, being too close to other traffic with lights going by. You could actually have those issues where your eyes are following other lights and so you may get that jerking motion. What I wanted you to understand is that there are defenses to failing that actual nystagmus test and so all is not lost upon you failing those three clues.
We will be doing a whole series on the standard field test sobriety and I want you to watch our videos and stay tuned. There will be a lot more to show after this. Thank you and thanks for watching and tune into our channel. Thanks. Bye.

This video was presented by: Mark Rollins