Articles on South Carolina Law

SC Field Sobriety Tests Part 1:Horizontal Gaze Nystagmus Eye Test

by | Jul 12, 2018 | Criminal Defense, DUI

Horizontal Gaze Nystagmus Eye Test

I have had many clients call me and tell me they are never going to beat their DUI case. My job is to dissect each case and carve out the defenses.

People worry about the high number they blew on the breathalyzer and believe they will never beat a DUI case because of that reading. But there are many pieces to the puzzle of a DUI case. The breathalyzer is a computer and like any other machine, can make errors.

Did you know that your attorney can obtain the exact breathalyzer machine records that was used in your DUI for months, or even years before or after your DUI?

The records reflect the errors that the machines make. Not only can the breathalyzer machine have errors, the video and audio footage from your DUI is key to your defense.

Did you know that SC law requires every DUI arrest to be audio and video recorded (with some limited exceptions)?

Read on to find out how important these recordings are in your DUI defense.

DUI Field Sobriety Tests

It is your choice as to whether you take a DUI Field Sobriety Test. Most people do not realize this because during the arrest they are intimidated by police presence, nervous, and don’t know what to do.

In general, you should always follow the commands of a police officer; however not every police officer is looking out for you during a DUI arrest and may not tell you that taking these tests are an option.

Why does it benefit you not to take the tests? The burden of proof in a criminal case is on the State (law enforcement) and the less you give them to work with to prove their case, the better your defenses can be.

There are three main Field Sobriety Tests: Horizontal Gaze Nystagmus, Walk and Turn, and One Leg Stand.

Let’s tackle these tests one by one, starting with the Horizontal Gaze Nystagmus (HGN) test.

Horizontal Gaze Nystagmus (HGN) Field Test

If you choose to take the Field Sobriety Tests in SC, you should know there are 3 main standardized Field Sobriety Tests. Law Enforcement must follow National Standards on the instructions phase of each test. They are looking for certain “indicators” or signs that you are impaired or drunk. The tests are designed to highlight these signs of impairment.

Other types of tests can be used if you are unable to perform these tests due to health issues, such as a previous head/brain injury, leg, feet or back problems, or balance issues. A law enforcement officer should ask you prior to the test if you have any of these types of issues. While you are not required to disclose each and every injury you’ve encountered in your lifetime, you should tell the police if you have concerns about taking the test due to any current or past physical limitations.

The Basics

It’s also known as the HGN, “eye” test,” or “follow the pen test.” This is typically the first test offered to a person pulled over for DUI. During this test, an officer holds object and asks you to follow it with your “eyes and your eyes only” as the officer moves an object either from side to side (horizontal) or vertical (up and down).

So what’s the purpose of this test? The officer is checking your resting nystagmus, which is a fancy word that describes whether the colored part of your eyes is “jumping” or moving involuntarily. If your eyes are jumping or moving involuntarily, it may be an indicator of impairment.

However, your attorney should know that there is a laundry list of other things that jumping eyes can mean:

  • Stroke,
  • Previous head injury,
  • Brain injury,
  • Vertigo,
  • Seizure,
  • Previous surgery, and the list goes on.

Horizontal (side to side) is the standard part of an eye test/ HGN test. But the vertical (up and down) test can also be used, typically after the horizontal test. The vertical test is supposedly a way to test for impairment due to substances other than alcohol (i.e. prescription, legal, non legal drugs or substances).

Problems with the HGN Test:

Video Quality

As an attorney having handled hundreds of these cases, I have never understood why this test is used because I am yet to view a dash cam video that is sophisticated and high definition enough to show my client’s eyes twitching or not twitching on video.

In most videos, my client is performing the tests in front of a police cruiser and the dash cam is recording. This means the dash cam would have to be hyper focused enough to zoom in on my client’s eyeballs. There is almost never a second officer in the patrol car operating the camera. The result? The only evidence we really ever have of whether my client passed or failed this part of the test is the testimony of the officer.

So we are supposed to go on what the officer says to be true? I can’t understand why SC has a mandatory video and audio recording statute, yet the clues of impairment on one of the most commonly used standardized tests (the “eye test” or “HGN” test) is unable to be captured on video.

Not Following Requirements

What are some of the things police can get wrong during this test, other than not capturing the clues of impairment up close enough for everyone to see?

Well, a lot of things. The national standards require the officer to explain the test fully before you begin. If you have questions about the test, you should ask and the police should be able to answer the question.

There is a number of times that the object should pass from left to right. There is a time frame/ time limit that this test should be performed in. Failure to abide by this time frame can mean that the officer causes eye strain, which can cause a false positive result of the test, making you appear to be impaired when you may not be.


Where an officer places you to perform the test is also important. Does the officer ask you to face traffic moving from side to side? If you are taking your test at night, are cars passing by in your side view (peripheral vision)? If so this could adversely affect the test results. Are other officers moving around in your peripheral vision?

The national standards instruct the officers to avoid movement in your side vision. Usually by the time you are performing the Field Sobriety Tests, there is more than one officer on the scene. The other officers should not be walking around or talking or distracting you during the time you are taking this test. The officer who is administering the tests should know this and take control of the environment where you are taking the test.

Stimulus Used

The stimulus (thing) used by the officer to administer this test is also important. The national standards require the stimulus used to stand out and be easily seen by the person who is taking the test. Is the officer using an ink pen? Does the ink pen stand out or it is easily visible while you are taking the test? Or does it blend in with the background? If you are taking the test at night, does the top of the pen have a light on it? Are you facing lights while you are trying to take the test?

The pen/stimulus used for this test needs to be eye level, according to the National Standards. Look at the height of the police officer, versus your height. The officer’s “eye level” may be very different from your eye level. The pen should be eye level with you, not the officer. Also, the amount of space between the stimulus/ pen and your eyes should be around 12-15 inches. There is even a stopping point from side to side that the officer should be adhering to.


The lighting is important for this test. For example, the blue police lights should be turned off during the administration of this test as well as the other field sobriety tests. The strobe-like lights are distracting and can affect the test results. Similarly, if there are fire trucks and/or ambulances at the scene, are those lights turned on or off during this test?

The distracting lights can be more than just police, fire, or ambulance lights. For example, a business/ restaurant sign with blinking or strobe-like lights can be an unforeseen distraction.

Weather Conditions

Weather conditions can also be important for this test. Are you taking this test in the pouring or sprinkling rain? It is a rare time that SC sees sleet, snow or hail? These factors can affect your test results. The officer is permitted to move you to a location out of this type of weather is no longer a factor.

Why You Need a DUI Defense Attorney

Did you learn more about DUI defenses merely from reading this article? I hope you did. Having an attorney on your side to help walk you through the process can be helpful to people facing DUI charges. This may be your first DUI case, but your attorney has been through more than one DUI case. With each case, your attorney gains experience in DUI defense.

Wouldn’t you like to benefit from this wisdom and training?

The effects of a DUI conviction last long after your court date. There are issues like mandatory classes (ADSAP classes), insurance hikes (SR22 insurance) for at least two years, and possibly an Ignition Interlock Device (IID) being installed on your vehicle, not to mention your driver’s license being suspended.

Once you are convicted of DUI, there is no way of getting a DUI conviction expunged from your criminal record.

Don’t get railroaded. Call Susan E. Williams today to see if she can assist you with your DUI defense. You can contact me today to discuss your case. Call 843-607-9800 now to speak to me.

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