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Field Sobriety Tests: Designed for Failure?

WHAT ARE THEY?

In various forms, Field Sobriety Tests (FSTs), have been used by law enforcement for decades as a means of establishing probable cause to arrest persons suspected of intoxication, especially, when driving. Examples are the “touch your nose” test, reciting the alphabet or counting numbers tests, and balancing tests.

The National Highway Traffic Safety Administration (NHTSA) has approved three different FSTs that it encourages all law enforcement agencies to administer roadside in suspected DUI/DWI stops, claiming a person’s failure of these tests either individually, or in combination, are accurate and reliable predictors of a Blood Alcohol Concentration (BAC) that can impair one’s driving ability. The three tests are:

• the Horizontal Gaze Nystagmus (HGN) test,
  
• the Walk and Turn (WAT) test, and
  
• the One Leg Stand (OLS) test.
  

Almost every state and local law enforcement agency now use these tests to assist the officer in obtaining probable cause to arrest drivers for suspicion of DUI/DWI. These tests are not scientifically sound, have been proven to be inaccurate, are very subjective (depending wholly on the officer’s interpretation of the driver’s performance of them—as opposed to a uniform standard), and in short, are calculated to make the person taking them fail! Let me explain what each of these tests entails, what it is supposed to establish, and let you decide if they are unreliable.

THE HGN TEST

Nystagmus is simply a quivering of the eye. In most people, it occurs constantly, and is imperceptive. Let’s ignore the fact that in addition to alcohol consumption, certain medicines, infections and illnesses, fatigue, and other factors (approximately 40 in all) that a person may be unaware of, can cause the nystagmus to be perceptible. All the officer administering the test is looking for is “evidence” of alcohol consumption. The officer is going to note whether the eye quivers when following an object he is moving slowly from side to side in front of the driver’s face. If it does so at the “onset of 45 degrees from center,” he is to score that each time for each eye. The highest score for each eye is 3, and for both eyes in combination, 6.

In the NHTSA-commissioned FST field validation tests conducted in San Diego, a handful of specially trained officers participating in the study gave HGN tests to 290 drivers of the 297 they stopped on suspicion of DUI over a period covering May through November. Fully 200 of the 290 drivers received HGN scores of 6, the highest possible score for that test. One would think -- as does NHTSA -- that an HGN score of 6 would certainly indicate a person has a high BAC. Not true!!

Seven of the drivers having a score of 6 on the HGN (and combined scores of 3 or more on the WAT and OLS) had actual BACs of less than 0.08 (only 2 were higher than 0.07, and 1 was as low as 0.028). On the other end of the scale, only 6 of the 290 drivers scored 0 (meaning they “passed”) on the HGN, though their actual BACs were higher in 4 instances than the lowest actual BAC of the 7 drivers mentioned above.

The San Diego study indicates the inaccuracy of HGN field testing as done by law enforcement officers in the field. Think about it – MORE THAN TWO THIRDS OF THE DRIVERS ADMINISTERED THE HGN TEST SCORED THE HIGHEST POSSIBLE NUMBER AND ONLY 7 OF 290 DRIVERS SCORED THE LOWEST POSSIBLE NUMBER! Though officers are trained and recertified in HGN testing, there are too many factors that can taint the test, including the potential bias of the officer formulated by observing erratic driving before making the stop.

Additionally, HGN testing is most accurately conducted in a doctor’s office where precision instruments are used, and the head is held in a stationary position throughout so that only the eye movement is gauged. Officers conducting the test roadside do not have that equipment, and are really, just estimating speed of movement of the object you are following, the distances, and the angles, which are critical factors in obtaining accurate results.

Can you judge at which point 45 degrees of eye movement occurs? Try it with and without a protractor. Think you are going to pass this test if you are stopped? Re-read two paragraphs above. If you do pass, immediately go out and buy a lottery ticket! It is your lucky day.

THE WAT & OLS TESTS

NHTSA describes these two tests as “divided attention tests” and promotes their use because driving is a “divided attention” activity. There are the physical aspects, and concomitant cognitive aspects, involved for each. In other words, a person is scored not only on how well he performs the physical aspects asked, but whether he does them when and how instructed. In other words, you have two chances to fail either of these tests – first, if you are physically unable to do it, and second, if your nervousness or bad hearing causes you to incorrectly follow to the letter the officer’s instructions.

In administering these tests, the officer must first explain to the driver what he wants him to do, and tells the driver, “Don’t start until I tell you to,” and “Don’t do this [such as raise your arms for balance, etc.]." The officer should not begin the scoring until he is certain you understand the conditions of the test, but if you begin before he tells you to start, guess what, you already have points scored against you on your “cognition” error (that is, you didn’t follow his instructions to the letter). That’s from the NHTSA instructions manual, not necessarily from the officer’s perspective. Strike 1!

NHTSA manuals specify these tests should be performed on a “level” surface. Good reasoning there. How can you be expected to balance yourself when walking a straight line and turning on even a slighted slanted surface? A flat surface should be a flat line; namely, 180 degrees. Right? Guess what, there is no roadway constructed with state or federal funds in Virginia that is totally flat. To prevent rainwater from pooling on road surfaces and increasing the risk of hydroplaning, highways, like the roofs of most houses and buildings, are pitched to allow water run-off to the sides. Because of variations in soil density, the under-surface preparation, and the amount of concrete or asphalt depth, none of the roadways across the country – and Virginia – are uniform. They are going to vary as to the degree of pitch, or slant. If the officer asks you to perform either of these tests at the side of the road, you are starting the test at a disadvantage because you are going to be standing on the low end of a slope, and not on a level surface. Strike 2!!

Not everyone can perform these tests with ease, or perfectly. Clinical researchers critical of them as a reliable gauge of impairment point out that age, body weight, injury, weakness and other factors will prevent some persons from successful completion of the tests. Try it yourself at home or at work, and see how you do.

For the WAT, stand erect with your left foot slightly ahead and your hands at your side. With your head down staring at your feet, start walking a straight line, beginning with your left foot, and count 9 steps, making sure that for each step, the heel of the lead foot touches the toe of the stationary foot. When you complete the 9 steps, turn around, without lifting a foot from the surface, and repeat the process. Every time you step off the line, miss a heel-to-toe contact, sway, lift an arm to regain balance, or not do the turn correctly, you score a point for a misstep. For the OLS, stand erect with your hands at your side, and lift either foot 6 inches from the ground with the toe pointing up at a 45-degree angle, and count aloud “1001, 1002, 1003,” until you get to 1030. A point is assessed against you each time you raise an arm to balance, let your foot drop, sway, or fail to count correctly.

In the field, only the officer is going to determine how you performed each test. They make mistakes. In a clinical study conducted in South Carolina in 1994, 21 individual volunteers with zero BACs were videotaped performing the WAT and OLS FSTs. The videotapes were shown to 14 veteran field law enforcement officers who were asked to identify which individuals were “too drunk to drive” based on their performance of these two FSTs. As a group, the officers were wrong 46% of the time!! In other words, 10 of 21 sober people failed. Only three individuals were rated as "unimpaired" by all officers. Five individuals were rated as having had "too much to drink" by all the officers who viewed the field sobriety tests. One other individual was rated as having had "too much to drink" by all but one officer. Also in the study, 15 % of these sober individuals were judged “too drunk to drive” based on their inability to correctly recite such things as their address or telephone number. Strike 3!

ANALYSIS OF THE FSTs

The FSTs do not appear to be accurate or reliable indicators of driver impairment. The officer may not tell you this, but performance of the roadside FSTs are voluntary, not mandatory. In other words, it is up to you to decide whether to perform them or not. Few people know this.

The Virginia Supreme Court has ruled that a driver’s refusal to perform FSTs, when combined with other factors observed by the officer (such as driving unusually, slurred speech, unsteadiness, argumentative attitude), can supply probable cause for an arrest for DUI, its reasoning being based on the assumption that the refusal was made because the driver knew he would fail the tests because he had too much to drink. Therefore, if you choose not to perform them, ask your lawyer if to rebut that assumption you should provide the officer plausible reasons for your decision, and ask that he note them in his report .

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