Standardized Field Sobriety Tests

Blog-DWI-Checkpoint-178x150When conducting a DWI investigation, officers are trained to use Standardized Field Sobriety Tests to determine if a person is impaired.  These tests have been verified by the National Highway Traffic Safety Administration.  Other tests that officers commonly use, including the Alphabet and Counting tests, are not recommended.  There are three standardized tests that officers are supposed to use to develop probable cause for arrest.

Horizontal Gaze Nystagmus

This is a test that checks the eye’s physiological response to a moving stimulus. An officer will move a pen or finger from left to right, back and forth.  The officer is supposed to follow a specific pattern while searching for clues of impairment. He or she will ask the person being tested to only move their eyes, and to keep their head still.  Some defendants think that they passed the test because they followed the stimulus without any problem.  However, the officer is not testing to simply see if the test subject can follow the pen.  He or she is testing to see if the person exhibits nystagmus, which is the jerking of the eye.  When a person has been drinking, they will display nystagmus. In some cases, a person will display vertical gaze nystagmus.  There are other causes for this response, including head trauma.  Vertical gaze nystagmus is typically used to determine if the person has a higher blood alcohol content.  Of course, there are other potential causes of nystagmus, including positional nystagmus and optikinetic nystagmus.  Some people have a natural nystagmus.  An officer can mistake any of these for a clue of impairment.  These clues are considered the most reliable, and the officer typically completes this test first.  This means that the officer may be biased toward finding clues on the tests that follow.  In addition, the video does not provide a view of the person’s eye movements.  At best, the video will provide a view of how the officer administers the test.  This may or may not be helpful.  The officer may make errors that invalidate the test, or they may administer it perfectly.

Walk and Turn

The next test that is usually given is the Walk and Turn.  The officer will request that the person keep their arms down by their side, place one foot in front of the other, and to count out loud as they walk nine steps down a straight line.  This test requires a person to follow a several instructions by the officer.  The intent of the test is to determine if a person is impaired, but frankly, it can be quite hard even for a person who is sober.  In Mecklenburg County, most police vehicle are equipped with a dashboard camera.  We can get this video and use it to evaluate the officer’s administration of the Field Sobriety Tests. The walk and turn test is one that a judge or jury can look at to make their own determination.  The HGN test is one that is difficult to see, but the walk and turn is one that people will automatically evaluate for themselves.  Performance on this test can cause a judge or jury to conclude whether a person is drunk or sober based on how they appear.

One Leg Stand

The final Standardized Field Sobriety Test is the One Leg Stand.  During this test, a person is required to keep their hands by their side, raise either of their legs six inches of the ground, look at their raised foot, keep their foot parallel to the ground, and count out loud, “one thousand one, one thousand two, one thousand three…” and so on until the officer tells them to stop.  The officer is supposed to stop this test after 30 seconds.  People who naturally have bad balance will perform poorly on this test.  This test can be very unnerving for people who have to stop and put their foot down to maintain their balance.  Like the Walk and Turn, this is a test that a judge or jury can look at for themselves to make a determination of sobriety.  Watching this test on video can be a powerful influence in a case because no matter what the officer says, the finder of fact can draw their own conclusions.

Additional Non-Standardized Tests

There are other tests that officers will commonly use in the field, even though they are not recommended by NHTSA.  One of the most common tests is the Alphabet Test, in which an officer will require a person to start reciting the alphabet at one letter, and finish at another letter.  Any error, such as starting on the wrong letter, ending on the wrong letter, or mixing letters up, will be considered a clue of impairment.  A similar test is the Counting Test.  An officer will frequently give a person a number to start at, and request that he or she begin counting backwards until a certain number is reached.  Clues of impairment include failing to begin at the right number, failing to stop at the correct number, and mixing up numbers.

There are three other non standardized tests that are commonly used.  The first is the Rhomberg Balance test.  This consists of closing your eyes, tilting your head back, and estimating a 30 second period.  During this time, the officer will try to pay attention to several clues, including swaying (front to back and side to side, whether the person keeps their head tilted back, and how accurate the person’s estimate of 30 seconds is.  The next example is the finger dexterity test.  This test consists of touching the thumb to the fingers of the same hand and counting out loud.  Finally, there is the Finger to Nose test, in which the person is asked to use their index finger to make contact with the end of their nose.  Despite the fact that these are non standardized tests, they are still used to evaluate a person’s sobriety.

Field Sobriety Testing – The Takeaway

Your performance on these tests can be a factor that can make or break your case.  If someone looks fine on video, the case against them may be significantly weakened.  If, on the other hand, the video looks bad, it may build the State’s case.  The tests are designed to test numerous abilities, including the ability to divide attention, short term memory, balance, and maintain focus.  The tests can be difficult for some people even when they are sober.  Some people with certain medical conditions, or of a certain age or weight, should not be required to attempt some field sobriety tests.  If a person is physically incapable of completing a certain sobriety test in perfect conditions, they should not be required to attempt the sobriety test on the side of the road while undergoing the stress of a DWI investigation.

In addition, these tests may be invalidated if they are administered incorrectly.  For instance, if the officer never instructs the person to keep their arms down by their side during the One Leg Stand, but then later considers the fact that the person raised their arms for balance as a clue of impairment, an argument may be raised that the clue is invalid.  Since the person was never told that they could not use their arms for balance, they cannot be faulted for using their arms.  This invalidates one of the four standardized clues of impairment that officers are trained to look for in the One Leg Stand test.  Depending on how the rest of the testing goes, there may be enough to attack the probable cause for the arrest.