Standardized Field Sobriety Tests

When stopped for suspicion of DUI, an officer will almost certainly conduct a battery of standardized field sobriety tests.  There are three tests recognized by the National Highway Traffic Safety Administration.  The three tests include horizontal gaze nystagmus, walk and turn, and one leg stand.  As a DUI defense attorney and former police officer, I have had the opportunity to be trained in the testing of the field sobriety tests.

The first test often conducted is the horizontal gaze nystagmus.  There are six “clues” associated with the horizontal gaze nystagmus test.  These clues are 1) lack of smooth pursuit; 2) distinct nystagmus at maximum deviation; and 3) onset of nystagmus prior to 45 degrees.  An officer can notice each of the three clues in both the right and left eye.  The officer will give the “suspect” a set of instructions and hold a stimulus 12 to 15 inches in front of the “suspect’s” face.  The officer will look for the nystagmus, which is an oscillating of the eyes, while the “suspect” follows the stimulus.  The National Highway Traffic Safety Administration conducted a study in which “NHTSA research found that this test allows proper classification of approximately 88 percent of suspects.”  This does not take into account the numerous studies in which the fallacies of this test have been pointed out or the fact that there are 38 different causes of nystagmus.  If an officer decides that a “suspect” has exhibited four clues, this is sufficient probable cause to arrest.

The second test conducted is often the walk and turn.  This test consists of two stages, first the instruction stage and then the walking stage.  The instruction stage simply consists of the officer instructing the “suspect” on how to perform the test.  During this stage, two clues may be observed.  First did the “suspect” begin the test too soon and second did the “suspect” maintain their balance during the test.  The next stage is the walking stage.  The clues that may be observed are 1) stops while walking; 2) misses heel to toe; 3) steps off the line; 4) uses arms to balance; 5) turned improperly; and 6) wrong number of steps.  If the officer decides the “suspect” showed signs of two clues, the National Highway Traffic Safety Administration feels that an individual will have a blood alcohol concentration of .08 or greater 79% of the time.

The third test conducted is the one leg stand.  This test also consists of two stages, first the instruction stage and then the balance and counting stage.  During the instruction stage, the officer will instruct the “suspect” to stand with their feet together, keep their arms by their side, and maintain that position until told to do otherwise.  The second portion of the test requires the “suspect” to raise one leg in the air, about six inches off the ground, with their foot pointed out.  They must also keep their arms by their side, keep their eyes on their elevated foot, and count out loud until told to stop.  This test generally lasts for 30 seconds.  The officer is looking for four clues; did the “suspect” sway, use arms to balance, hop, or put their foot down.  The National Highway Traffic Safety Administration feels that an individual will have a blood alcohol concentration of .08 or greater 83% of the time if two of the four clues are observed.

It is important to remember that you have the right to refuse to take these tests without any reprisal.  Even if a person decides to take the standardized field sobriety tests, a competent DUI defense attorney can point out the severe fallacies with the tests.