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HGN and Head Trauma

If you have been pulled over in Georgia on suspicion of DUI, the investigating officer will probably ask you to perform a battery of standardized field sobriety tests. This request may take the form of any number of questions, such as “can we just check to see if you are safe to drive?” or “we want to perform some tests before we let you on your way, is that alright?”. These tests are not required, and declining to perform these tests cannot be used against you in a prosecution of DUI. For this reason, it is better to decline to perform any tests, no matter how much reassurance the police officer gives you that they are “just to make sure you are safe on the roads.”

Still, many people opt to perform the tests, either because they don’t see the harm, they wish to be congenial with the officer, or because they don’t know that they can decline to perform the tests. If you choose to perform the tests, the officer may ask you if he can “take a look at your eyes.” This is an indication that he is about to perform the first of three standardized field sobriety tests, the horizontal gaze nystagmus.

This test is considered to be a “scientific” test, and because of this, it is important that the officer comply with his training as exactly as possible. The test must begin with a number of questions designed to medically qualify the participant. The officer is trained that he must ask you whether or not you have recently had any head, neck, or brain injuries, as these kinds of trauma can affect whether someone exhibits nystagmus, even if not under the influence of alcohol. It is common practice to ask whether or not the subject has “any eye problems” or vision issues, but this is not enough. The officer must also determine that it is appropriate to use this test. If the subject has been in a recent accident, suffering from whiplash, a concussion, vertigo, or some other balance and coordination related condition, the HGN test may not be accurate or reliable.

If you have been in an accident at the time of your DUI investigation, the officer may have overlooked potential head trauma before administering this test. As a result, the “clues” of the test may be unreliable, and could be subject to suppression before trial.

It is important to understand your rights and protections when you are charged with DUI. If you want an attorney that is knowledgeable about DUI police training and procedure, call our office for a free consultation at 404-581-0999. Written by Attorney Katherine A. Edmonds.

What to expect during a DUI stop in Chamblee, GA

By: Attorney Alex Henson

If you are suspected of driving under the influence of alcohol in Chamblee, GA you might be pulled over and investigated by police. What can you expect during a DUI stop?

First, the officer might ask you if you’ve had anything to drink. You have the right to remain silent and refuse to answer the question, but always be polite and respectful. Any statements you make could be used against you later in court.

Next, the officer might ask you to perform certain exercises to see if you are safe to drive. These exercises are called Standardized Field Sobriety Tests and your performance could be used against you in court later. The most common of these tests are the horizontal gaze nystagmus (HGN), the one leg stand, and the walk and turn. It is voluntary to participate in field sobriety tests. Refusing to participate cannot be used against you in court later.

The officer may decide that you are under the influence and less safe to drive. If the officer decides to arrest you, he or she may read you Georgia’s implied consent statement and request chemical testing of your breath or blood. These tests are voluntary, but refusal can result in your license being suspended.

If you are arrested for DUI in Chamblee, GA for DUI, your case will be sent to Chamblee Municipal Court. In the Chamblee Municipal Court, you will have the opportunity to resolve your case. However, if you decide you want a jury trial, your case will be transferred to the State Court of DeKalb County.

If you have been arrested for DUI in Chamblee, GA and would like a free consultation, call us at (404) 581-0999.

What to expect during a DUI stop in Atlanta, GA

By: Attorney Alex Henson

If you are suspected of driving under the influence of alcohol in Atlanta you might be pulled over and investigated by police. What can you expect during a DUI stop?

First, the officer might ask you if you’ve had anything to drink. You have the right to remain silent and refuse to answer the question, but always be polite and respectful. Any statements you make could be used against you later in court.

Next, the officer might ask you to perform certain exercises to see if you are safe to drive. These exercises are called Standardized Field Sobriety Tests and your performance could be used against you in court later. The most common of these tests are the horizontal gaze nystagmus (HGN), the one leg stand, and the walk and turn. It is voluntary to participate in field sobriety tests. Refusing to participate cannot be used against you in court later.

The officer may decide that you are under the influence and less safe to drive. If the officer decides to arrest you, he or she may read you Georgia’s implied consent statement and request chemical testing of your breath or blood. These tests are voluntary, but refusal can result in your license being suspended. If you have been arrested for DUI and would like a free consultation, call us at (404) 581-0999.

Field Sobriety: Horizontal Gaze Nystagmus

What is Horizontal Gaze Nystagmus?


The HGN test evaluates abnormal eye movement caused by the influence of an intoxicant such as alcohol or drugs. Nystagmus is an involuntary jerking movement of the eye.[1] There are several forms of nystagmus or jerking of the eyes. Of the forty-plus types of medically recognized nystagmus, officers are trained on only three categories; vestibular, neural, and pathological disorders and diseases. Furthermore gaze nystagmus is only one of three types of neural nystagmus. Because there are so many types of nystagmus, it is easy for an officer to confuse the nystagmus they believe is caused by alcohol with another type of nystagmus not caused by alcohol but some other condition. Such other conditions include, but are not limited to: mental disorders, vertigo, inner ear fluid imbalance, head trauma, stroke, multiple sclerosis, diabetes, and stroke. Therefore, it is incredibly important the test be properly administered as to rule out other types of nystagmus not caused by an intoxicant which may mimic the nystagmus caused by intoxicants.

Measurements

Measurement of nystagmus is accomplished through three different methods. (These are known as the “six clues” recognized by NHTSA as valid indicators of HGN; that is, three clues for each eye). The first measuring technique is to look for lack of “smooth pursuit,” i.e., rather than following a moving object smoothly, the eye jumps or tugs. This technique is not a description of nystagmus. It is a condition that can result from many factors, such as the flashing blue lights of the officer’s vehicle or the passing lights of other motorists (optokinetic nystagmus).

           
The second method of measurement is to determine whether the nystagmus becomes more “distinct” when the eye is moved to the lateral extreme (so no white is apparent between pupil and outer edge of eye). Again, many people can have nystagmus or nystagmoid-like eye movement at this point of extreme lateral gaze and not be under the influence of alcohol or drugs.

           
The third method is to measure the angle of onset of nystagmus. By measuring the angle at which the eyes begin jerking. Nystagmus as a result of an intoxicant should begin at or before the 45 degree angle from the straight ahead gaze. There should be a fast component in the direction of gaze, with a slow recovery phase back towards center.

Pre-Test Checks

HGN testing should be preceded by a series of questions designed to ensure the subject is not medically disqualified from taking the test. “Officers are reminded to ask questions about the subject’s eye and general health conditions prior to administering the HGN test.”[1] Additionally, “if there are any abnormal findings on the pre‐test checks, the officer may choose not to continue with the testing. If HGN testing is continued, officers are reminded this does not follow the standardized protocol and should acknowledge such in any report.”[2] After asking these preliminary medical clearance questions, the officer is ready to proceed with administering the test.

Test Procedures

To properly administer the HGN test, the officer must:

  1. have the suspect remove his eye glasses;
  2. properly instruct the suspect that the officer is going to check his eyes and that his is to hold his head still and follow the stimulus with his eyes only and to keep following it until he is told to stop;
  3. hold the stimulus 12-15 inches in front of the subject’s face;
  4. check to determine if both eyes track the movement together (equal tracking), check for resting nystagmus (caused by certain medical conditions unrelated to alcohol consumption) and to ensure the pupils are of the same size (this step rules out other potential causes of nystagmus unrelated to alcohol consumption);
  5. keep the tip of the stimulus slightly above the subject’s eyes;
  6. always move the stimulus smoothly across the subject’s entire field of vision;
  7. always check for all 3 clues in both eyes, starting with the left eye;
  8. check the clues in this sequence: lack of smooth pursuit; distinct and sustained nystagmus at maximum deviation; onset of nystagmus prior to 45 degrees;
  9. always check for each clue at least twice in each eye;
  10. the typical time for each pass is two seconds out and two seconds back;
  11. when checking for distinct nystagmus at maximum deviation, the officer is to hold the subject’s eyes in the extreme position for at least four seconds;
  12. when checking for the onset of nystagmus prior to 45 degrees, it should take the officer 4 seconds to move the stimulus from the suspect’s nose to the angle—once jerking of the eye is first observed the officer is to stop moving the stimulus to ensure the jerking continues (validate nystagmus);
  13. total the clues (need to observe at least four out of six clues to indicate impairment); and
  14. check for vertical gaze nystagmus (separate test to determine if subject has taken a high dose for that particular subject).

Is HGN Accurate?


 In September, 2007, NHTSA conducted another study, “The Robustness of the Horizontal Gaze Nystagmus Test.” This study examined HGN in depth and, amongst other experiments, tested the false positive rates associated with improper administration of HGN. A false positive indicates a subject whose BAC was below 0.08 but the examiner nonetheless observed four out of six clues. The results were surprising. Evenwhen properly administered, 36.1% of test subjects falsely exhibited a positive result. Subjects whose stimulus was held too low (at eye level) exhibited a false positive rate of 52.7%.Subjects whose stimulus was held too high (four inches above eye level) exhibited a false positive rate of 61.1%. This is just one example of how one small error in administering the HGN test can produce a false result.

Summary

Attorneys need to be familiar with the instructor and participant NHTSA manuals, new case law, and the facts of their case to ensure the HGN test is properly administered and interpreted. As we saw, even the slightest deviation can compromise the validity of the test. For non-lawyers, it is important to know the HGN test, along with the other FSTs (discussed in Part III and IV), are entirely voluntary. Therefore, you should never consent to the participation of FSTs.           

  If you have been arrested for driving under the influence, contact the law firm of W. Scott Smith at 404.581.0999 today for a free case evaluation. You’ll find a local Atlanta DUI attorney ready to aggressively fight on your behalf. You can also find out more detailed information about Atlanta laws here.

by Casey Cleaver


[1] Session 8, page 29 of 95.

[2] Session 8, page 29 of 95.


[1] The NHTSA manual defines Horizontal Gaze Nystagmus (HGN) as, “involuntary jerking of the eyes, occurring as the eyes gaze side to side. In addition to being voluntary, [the] person is usually unaware it is happening [and] the person is powerless to stop it or control it.” The Manual also states that, “alcohol and certain other drugs cause HGN.” Session 8, page 18 of 95.

VIDEO – Horizontal Gaze Nystagmus Test

You’ve been stopped for DUI and the officer asks you to follow their finger with your eyes? What is this horizontal gaze nystagmus field sobriety test? And can it even be passed? That is the subject of today’s Peach State Lawyer video blog.

Hello, I’m attorney Scott Smith and today I’m standing in our mock trial courtroom. We’re talking about being asked out of your car after only having two drinks. The officer asks you to face him and with your hands by your side, feet shoulder width apart to follow his pen with your eyes. He asks you if you wear glasses or contacts or if you’ve had any recent head injuries. You’re about to perform the horizontal gaze nystagmus field sobriety test. It’s commonly known as the HGN test, or in the DUI world, the “eye” test.

What is this test?

The horizontal gaze nystagmus field sobriety test was originally designed by optometrists to diagnose medical issues within your eyes. The test checks for the involuntary jerking of your eye as your eyes move side to side horizontal to the floor following an object. Researchers determined some substances, particularly ethyl alcohol, and other central nervous system depressants, inhalants, and the drug PCP can cause horizontal gaze nystagmus in your eyes after use.

The horizontal gaze nystagmus field sobriety test, when properly performed looks for six clues of impairment. In Georgia DUI investigations, this test is the first of the standardized field sobriety evaluations.

Before the test can be performed on anyone, the officer is supposed to make sure both of your pupils are of equal size and your eyes move together from side to side. If you are having eye issues, the officer is supposed to discontinue the test immediately.

The clues are established in pairs. There are three tests performed that look for clues of impairment. The first test, called lack of smooth pursuit, is performed by the officer moving his finger back and forth across your field of vision, checking for nystagmus in both eyes as his finger or pen light is moving.

Because your eyes work together, each clue will be present in both eyes. If the officer says they notice a clue in one eye but not the other, the test would not be valid.

The second test is called distinct and sustained nystagmus at maximum deviation. It is where the officer moves his finger to the edge of your field of vision and holds it there for a minimum of four seconds to determine if your eye continues to exhibit sustained jerking when it is fixed on his finger at the edge of your field of vision.

These tests are designed to build upon each other, so you should never see clues present for distinct and sustained nystagmus at maximum deviation unless clues are present for lack of smooth pursuit.

The third and final test is called onset of nystagmus prior to a forty-five degree angle. The test is performed by the officer moving his finger slowly from the center of your field of vision until they reach a forty-five degree angle. When the officer begins to see nystagmus they are supposed to stop their finger and hold it to confirm the sustained jerking of the eye.

That’s it. That’s the entire horizontal gaze nystagmus field sobriety test. There’s nothing you can do to pass it. It’s all about the involuntary jerking of the eye and trusting that the officer in his report has documented his observations accurately.

As you can imagine, there are things that an experienced attorney can look for to determine whether the tests are performed correctly. If the tests are not performed correctly, an experienced DUI attorney can ensure the test should not be admitted into evidence or at trial against you.

Have you been recently arrested for DUI and asked to take this eye test? Do you have questions about the test? We’re available twenty-four hours a day, seven days a week to talk to you. Call us today for a free consultation. Our telephone number is 404-581-0999.

Thank you.