It’s late at night, you are coming back from dinner, and you get pulled over by an officer. The officer tells you that they stopped you because you ran a stop sign, and asks for your license and registration. Your nerves getting the better of you and you stammer your reply while you fumble with your wallet. The officer narrows his eyes and he orders you out of the car.

After you get out of your car, the officer tells you that he is going to administer a series of field sobriety tests to make sure that you are able to drive. Not knowing that you have any choice, you perform three tests pursuant to the officer’s instructions…and soon find yourself in handcuffs. You ask why, but the officer tells you that there is simply too much to explain.

So, let us explain it for you.

The DUI Field Sobriety Tests Are Voluntary

The first thing that you need to know is that participating in field sobriety tests is voluntary. While not participating in the tests will usually guarantee that you will be arrested, anyone who has been in this situation knows that participating in the tests certainly does not guarantee that you will be let go. So, while it may not feel like it, you do have the right to say no.

First DC DUI Test: Horizontal Gaze Nystagmus

If you do decide to take the tests, the first field sobriety test that you will perform is called the Horizontal Gaze Nystagmus (HGN) test. During this test, the driver is told to follow a stimulus (usually a pen, penlight, or an eraser on a pencil) with his eyes from side-to-side. The officer is looking for nystagmus or involuntary jerking of the eyes. While every person’s eyes involuntarily jerk at a certain degree, eyes begin jerking at an earlier degree as a person’s blood alcohol content increases.

As the driver’s eyes follow the officer’s stimulus, the officer looks for three different things (called “clues”).  First, the officer looks for whether the eyes move side to side smoothly, or whether the eyes jerk noticeably. Second, the officer looks for whether the eyes jerk distinctly when the driver’s eyes move as far to the side as possible and is kept at that position for four seconds. Third, the officer looks for whether the eyes start to jerk prior to a forty-five (45) degree angle as the eyes move to the side. Each eye is checked, beginning with the driver’s left eye. The officer moves the stimulus side-to-side twice before each eye to look for each of the clues of nystagmus. Each “clue” in each eye is one point, for a total of six possible clues.

Second DC DUI Test: Walk and Turn

The other two tests that are administered are focused on examining whether the driver can concentrate on more than one thing at a time. The idea is that drivers must be able to simultaneously drive and react to outside stimuli in order to safely operate a vehicle, and alcohol is said to reduce a person’s ability to divide attention.

The first divided attention test is the Walk and Turn (WAT) field sobriety test. The WAT is separated into two phases: (1) the instruction phase; and (2) the walking stage. During the instruction phase, the driver is required to stand with their feet in a heel-to-toe position with their hands at their side while the officer explains the instructions for the test. Once the officer is done with the instructions, the walking stage begins. The driver has to take nine heel-to-toe steps, turn in a very specific (and unnatural) manner, and return back heel-to-toe nine steps while counting the steps out loud.

During this WAT field sobriety test, the driver’s attention is divided between balancing tasks (heel-to-toe), attention tasks (counting out loud), and a short-term memory task (recalling the instructions). The officer is looking for eight possible clues during the WAT test: (1) balance during the instruction phase; (2) starts before instructed; (3) stops while walking; (4) steps off the line; (5) uses arms to balance; (6) does not touch heel to toe; (7) improper turn; and (8) incorrect number of steps.

Third DC DUI Test: One Leg Stand

The final test is called the One Leg Stand (OLS) test, aptly named because the test requires the driver to stand on one leg. Specially, the driver is required to raise one foot six inches off of the ground, looking at the raised foot, and slowly count to thirty out loud in the odd format of “one thousand one, one thousand two,” and so on. The test is supposed to examine balance and attention. The clues that the officer looks for during the OLS field sobriety test are: (1) sways when balancing; (2) uses arms to balance; (3) hopping; and (4) puts foot down.

Of course, when an officer is administering the DUI tests, the officer does not tell the driver what clues they are looking for or what clues the driver showed. In an already nerve-wracking situation, it is not surprising that many are unable to perform the tests for the very first time exactly as instructed – regardless of their intoxication level. This unfamiliarity is just one of many other reasons discussed here, as to why these field sobriety tests are unreliable.  Hopefully this article will help to ensure that at least the unfamiliarity factor of these tests is lessened for those who may find themselves in an unfortunate DUI situation in the future.