Field Sobriety Testing

Before being arrested for DUI most people are going to be asked to perform Field Sobriety Tests, or "FSTs". There are three standardized tests that have undergone scientific study, primarily by the National Highway Traffic Safety Administration (NHTSA): the Horizontal Gaze and Nystagmus ("HGN"), the Walk and Turn ("WAT"), and the One Leg Stand ("OLS"). Two other common (but not standardized) sobriety tests are the Romberg Balance Test and the Finger to Nose Test. Understanding these tests and how they are supposed to be done, allows me to attack the results in court to show how little value they really are in determining impairment by alcohol or drugs.

Horizontal Gaze Nystagmus

HGN is considered the most reliable test because it involves the involuntary jerking of the eyes. The officer administers this test by using a stimulus, such as a finger tip or a pen, holding it just above the subject's nose about 12-15 inches away, and asks them to look at it without moving their head as he passes it back-and-forth several times.

For this test, there are three clues in each of two eyes: lack of smooth pursuit, angle of onset of nystagmus prior to 45 degrees, and nystagmus at the extremes. If four of the six clues are detected, the validation studies have shown there is a 70% chance of the suspect having a blood alcohol level over .10%.

The problem with this test aside from the myriad causes of nystagmus that occur naturally in humans is that the accuracy of the test is questionable at lower blood alcohol levels. Moreover, it cannot be used to determine blood alcohol level or impairment—only that alcohol is in one's system.

The One Leg Stand

In the One Leg Stand, the person is instructed to stand with their feet together with their hands at their side while the instructions for the test are given. The subject is required to stand with one foot of their choosing six inches off the ground, point their toe, keep their foot level and told to look at their foot while counting to thirty seconds out loud. The officer looks for four clues, most easily remembered using the acronym PUSH:

  • Put foot down
  • Use arms to balance
  • Sways
  • Hops

If two of four clues are detected, studies have shown a 65% chance the suspect has blood alcohol concentration greater than .10%. However, as with many of these tests, the officers often do not properly instruct the test and do not know the clues. If that's the case, then the officer's opinion is invalid.

The Walk and Turn Test

In this test, the suspect is told to stand with his right foot in front of the left, hands at his sides, and told to remain there and not begin the test until he is instructed. The officer gives the remaining instructions for the walking portion while noting if the person can maintain his balance while listening. Once instructed, the walking stage commences with the subject, starting with his left foot, taking 9 heel-to-toe steps forward, then, with his left foot planted, take several small steps with the right foot while turning on the left foot, until a 180 degree turn is made. Then the right foot is placed back in starting position in front of the left foot and, again starting with the left foot, 9 heel-to-toe steps back are made back. The steps should be counted out loud, keeping one's hands to their sides and staying on the line.

The clues are: 1) ability to remain in position during instructions, 2) starting too soon, 3) gaps between steps greater than one-half inch, 4) stops while walking, 5) stepping off of the line 6) improper number of steps, 7) raising arms greater than 6 inches from one's sides, and 8) improper turn. If two of the eight clues are noted, there is a 68% chance that suspect has a .10% blood alcohol concentration or more.

The validity of this test depends on the subjective evidence of the test scene. Cracks in the pavement, asking the suspect to follow an imaginary line as opposed to a line on the road (whose imagination are we using, the officer's or the subject's?), the spacing between the individual steps, the position of the defendant's arms used to balance themselves, and other inconsistencies in the protocol and evaluation can be used to refute the officer's determination. Only with a careful examination of the evidence and a thorough knowledge of the testing procedures will it be possible to detect these cracks in the officer's interpretation of the results.

Romberg Balance Test

The Romberg Balance Test is a non-standardized test that requires the subject to stand with his feet together, hands at his sides, tilt his head back, close his eyes, count to thirty seconds in his head, and then putting his head down and opening his eyes when finished. The officer is looking for the ability to both follow directions and divide attention between small muscle memory, short term memory and balance. This is not a standardized test with specific instructions, demonstration and performance assessment. Attacks on this can be made in that officers will acknowledge they have no standards, and the fact they focus on whatever they want as proof of impairment while ignoring the proper performance of other aspects.

Finger to Nose Test

The second non-standardized test used commonly is the Finger to Nose Test. The subject is told to stand with his feet together, his hands at his sides with his palms facing forward. The subject is told to basically make a fist with their index finger extended downward towards their feet, close their eyes and alternate using each finger to touch, back and forth, left and right, the tip of their nose with the tip of his finger. Again, without standardization, officers instruct it differently, and it is impossible for an officer to make any conclusions about impairment, and frequently they are left nit-picking about whether the tip or the pad of the finger was used. That has nothing to do with impairment and should be pointed out.

How to Beat Standardized Field Sobriety Tests

It is important to always remember that standardized field sobriety tests have been validated by NHTSA only when used with a specific set of instructions, a specific demonstration, and specific clues or cues must be noted. The officer should give the instructions for a test word for word. Secondly, the officer must demonstrate them properly. Finally, the officer must actually know the clues or cues to look for to judge performance properly. If you have a standardized test without standardized instruction, demonstration and assessment, the validity of the results is compromised and therefore useless. Cross-examination of the officer is the key opportunity to attack the FSTs. I have taken the twenty-four hour class that most officers get, so I know how to attack an officer on cross to invalidate the officer's conclusions of impairment. This can demystify this junk science to a jury and help win your case.