Standardized Field Sobriety Testing

There are several Standardized Field Sobriety Tests, or SFSTs, that officers commonly perform when they are attempting to evaluate whether a person is under the influence of alcohol or a controlled substance, and several others that officers administer in addition to these when they suspect drugs are involved.  This article will go over the different kinds of tests, the reasons why you should consult a Georgia DUI Defense Attorney if you have performed these tests during a traffic stop, and your rights pertaining to Standardized Field Sobriety Tests.

These tests include:

  • The Horizontal Gaze Nystagmus (HGN) Test,
  • The Vertical Gaze Nystagmus (VGN) Test,
  • The Walk and Turn Test, and
  • The One-Leg Stand Test.

While it technically is not considered part of the battery of Standardized Field Sobriety Tests, many officers will then administer the Alco-Sensor Portable Breath Test.

Horizontal Gaze Nystagmus

Most people recognize that police officers are doing some sort of sobriety test when they are moving a stimulus in front of a person’s face, and many people believe that they passed the test if they were able to follow the stimulus with their eyes. They are incorrect. The officer is not looking for whether a person is able to follow the stimulus, but rather is actually looking for something called nystagmus.

Nystagmus is an involuntary jerking of the eye. Perhaps obviously, horizontal gaze nystagmus is when the eye jerks while moving side to side, and vertical gaze nystagmus is when the eye jerks when moving up and down. Nystagmus, both of the horizontal and vertical varieties, can be caused by ingestion of alcohol or certain controlled substances (though not all).

This field sobriety test is called the Horizontal Gaze Nystagmus (HGN) Test. HGN is usually the first test an officer conducts when he or she suspects that a person may be under the influence of alcohol or another substance.

Before beginning the test, officers are trained to instruct the individual to:

  • Remove eyeglasses,
  • Put feet together, with hands by his/her sides,
  • Keep his/her head still,
  • Look at the stimulus,
  • Follow the stimulus with the eyes only, not with the head, and
  • Continue watching the stimulus until the test is over.

The HGN test has three parts, and they should be conducted in the following order:

  • Lack of Smooth Pursuit
  • Distinct and Sustained Nystagmus at Maximum Deviation
  • Onset of Nystagmus Prior to 45 Degrees

Before conducting the three parts of the HGN test, the officer must ensure that the individual is medically qualified to take the test. Officers are instructed to check for:

  • Equal pupil size,
  • Resting nystagmus, and
  • Equal tracking (meaning that the eyes move in unison).

If eyes do not track together or the pupils are unequal in size, the individual may not be a good candidate for the HGN test because these are indicative of a medical disorder or injury. Officers are instructed to ask about eye conditions and overall health. This is because there are other kinds of nystagmus that are not caused by alcohol or drug use and could create a “false positive” on the test. For example, if a person has a brain injury, brain tumor, or a disease of the inner ear, he or she might have nystagmus. If these conditions are present, the officer may choose not to continue with the test.

In order to check for these three things, the officer positions the stimulus 12-15 inches in front of the individual’s nose and slightly above eye level. He or she looks for resting nystagmus and equal pupil size at this time. He or she then moves the stimulus from the center to the far right, to far left and then back to center. It should take about 2 seconds for the stimulus to move from the center to the side. The officer is checking to ensure that both eyes are moving together. He or she will then move on to testing for lack of smooth pursuit.

Lack of Smooth Pursuit

In this test, the officer is checking to see if the person’s eyes move smoothly as the eyes follow the stimulus. If a person is impaired by alcohol, often his or her gaze will be jerky, jumping from one location to the next.  This is involuntary and is often not perceptible to the individual.

Officers are taught to hold the stimulus 12-15 inches from the individual’s nose, and slightly above eye level. The officer should move the stimulus all the way to the right (checking the left eye), then all the way to the left (checking the right eye), then back to center. Just like in the previous test (for equal tracking), it should take approximately two seconds for the stimulus to go from the center to each side. The officer should make at least two complete passes with the stimulus. Each eye is checked independently; thus, if the officer observes a lack of smooth pursuit in both eyes, two clues are noted on the test.

Sustained and Distinct Nystagmus at Maximum Deviation

In this test, the officer is checking to see whether nystagmus is present when the eye is held all the way to either side for a period of time.

To conduct the test, the officer (again) holds the stimulus 12-15 inches from the individual’s nose and slightly above eye level. The officer moves the stimulus to the right side (checking the left eye) so that the eye is as far to the right as it can go and holds it there for a minimum of 4 seconds. He or she then moves the stimulus towards the left side (checking the right eye) and again holds it there for a minimum of four seconds. Officers are instructed to test each eye twice.

Just as in the previous test, each eye is evaluated independently, and if the officer observes a sustained and distinct nystagmus in both eyes, two clues are tallied. Note that the nystagmus must be distinct, a mild jerking of the eye is insufficient here.

Onset of Nystagmus Prior to 45 Degrees

In this test, the officer is testing to see at what angle nystagmus begins when he or she begins moving the stimulus to one side. HGN is not used to determine a specific blood alcohol concentration (BAC). However, it is believed that, if nystagmus begins just before or right at 45 degrees, he or she has around a 0.08 blood alcohol concentration, which is the legal limit. For a person with a much higher blood alcohol concentration, the onset of nystagmus may be much earlier, as soon as the eye leaves the center point.

To administer this test, the officer once again holds the stimulus 12-15 inches in front of the nose, and slightly above eye level. He or she moves the stimulus more slowly this time so that it takes approximately 4 seconds to move the stimulus from the center to the 45-degree line, noting the degree of onset of the nystagmus. Officers are trained to test the left eye first by moving the stimulus to the right, and then the right eye by moving the stimulus to the left. Each eye should be checked twice.

Again, each eye is evaluated independently. If the officer observes that nystagmus began prior to 45 degrees in both eyes, two clues are tallied.

The Vertical Gaze Nystagmus (VGN) Test

Vertical Gaze Nystagmus (VGN) is when the eyes jerk involuntarily when the eyes look upward at maximum elevation. The presence of VGN in an individual is indicative of a high level of alcohol for that individual. VGN should not be present without HGN, as substances that cause VGN also cause HGN.

Officers usually test for VGN after they complete the HGN test.

To test for VGN, officers are trained to hold the stimulus horizontally about 12-15 inches from the person’s nose. The officer then moves the stimulus upward, until the individual’s eyes are looking up as far as they can go. This position must be held for at least 4 seconds while the officer determines whether the eyes are jerking upward.

The Walk and Turn Test

The two remaining tests, the Walk and Turn and the One Leg Stand, are known as “divided attention” tests. This means that individuals are being tested not only on their balance and coordination but also on their ability to listen to and follow the officer’s instructions.

Many of us have seen the news story of the student who juggles for officers to prove his sobriety. While that is an extreme example, some people feel confident enough to try to extra actions to prove their sobriety, like taking extra steps or dancing the steps instead of walking in a straight line. But because this is a divided attention test and the failure to follow instructions is counted against you, I would never recommend this.

The Walk and Turn test has two phases:  the instructions phase and the walking phase. Typically, the officer tells the individual to get into a heel-to-toe position while the officer gives the instructions. The officer tells the person that he or she will take a series of 9 heel-to-toe steps in one direction, keeping his/her hands down by his/her sides. Once he or she takes 9 steps, he or she will step out of line, taking a series of small steps in order to turn around, and will then take 9 steps back to the starting position. The officer will typically demonstrate a few steps of the test.

For purposes of the Walk and Turn, clues are noted when:

  • The individual cannot keep balance during the instruction phase. The officer will instruct the individual to remain in the heel-to-toe position while listening to the instructions. For a clue to be noted here, the person must actually step out of line. Frequently, the officer will move out of heel-to-toe position here, and the individual will also break out of the heel-to-toe position, following the officer.
  • The individual starts the test before being told to start. For this to be counted as a clue, the person must be told not to start walking until instructed. Often people will begin walking while the officer is still giving instructions.
  • The individual stops while walking. This is not merely walking slowly, but actually stopping during the test.
  • The individual does not touch heel to toe. If the person leaves more than half an inch between the heel and the toe on any one step, this is counted as a clue.
  • The individual steps off line. This is where one foot goes entirely off the line.
  • The individual uses his/her arms for balance. For this to be counted as a clue, the arms must raise up more than 6 inches from the sides of the body.
  • The individual makes an improper turn.  The turn is probably the trickiest part of the test. Spinning or pivoting is incorrect and will count as a clue.  Loss of balance will count as a clue. The person must take a series of small steps in a circle to turn properly for this test.
  • The individual takes the incorrect number of steps. If a person takes fewer or more than 9 steps, this will be counted as a clue.

One Leg Stand Test

The One Leg Stand, like the Walk and Turn, is a divided attention test. As such, it has two phases, the instructions phase and the balance and counting phase.

The officer instructs the individual to raise his or her foot (either foot) 6 inches off the ground, then verbally count to 30. The officer will typically demonstrate the test briefly.

For purposes of the One Leg Stand, clues are noted when:

  • The individual sways while balancing.  This is a side-to-side or back and forth swaying that is distinct and noticeable. Slight tremors in the foot or body do not count.
  • The individual uses arms to balance.  If the arms move more than 6 inches away from the body, this is counted as a clue.
  • The individual hops during the test.
  • The individual puts his/her foot down during the test.  If the individual puts his or her foot down during the test, this is counted as a clue. Officers are instructed to continue the test after the person puts his/her foot down.

The Alco-Sensor

The Alco-Sensor is a portable breath test (PBT) that most police officers carry with them in their patrol vehicles. Many officers will ask individuals to blow into the Alco-Sensor after concluding the Standardized Field Sobriety Testing.

One important thing to note about the Alco-Sensor is that it does not measure your blood alcohol concentration (BAC). Instead, it measures mouth alcohol. This means that you can be stone sober, swish your mouth with Listerine (which contains alcohol), and blow a positive result on a PBT. The PBT does register a number, but because it is generally accepted that the number is not necessarily reflective of a person’s actual BAC, in court officers can only testify as to whether a PBT registered that a person was positive or negative for the presence of alcohol.

What can a Georgia DUI Attorney do about Field Sobriety Testing?

These tests are used to develop probable cause for an arrest. They are “standardized,” and therefore all officers are supposed to administer them in a uniform manner. This is because deviation from these standardized techniques can lead to arrests of sober drivers. Because of this, it is important that attorneys who work DUI cases know how these tests are supposed to be administered and can identify when the tests are not administered properly. The attorney then can file a motion challenging probable cause for a DUI arrest that occurred after a flawed investigation.

I have completed the same DUI detection course that Georgia State Patrol takes. As a result, when I watch a dashboard camera video of a DUI arrest, I immediately know when an officer fails to follow his or her training and properly administer all three tests. If you were subjected to Standardized Field Sobriety Testing and ultimately arrested for DUI, call me today.

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