DC Field Sobriety Tests

Standardized Field Sobriety Tests

A police officer may ask you to perform certain tests “just to prove you’re capable of driving safely.” The tests measure varying levels of physical coordination and the ability to listen and follow what the officer is telling you to do. The tests are not natural, some are open to serious criticism, and are often not properly explained by the officer.
The National Highway Traffic Safety Administration  validated a series of Standardized Field Sobriety Tests used by police officers. They are the only tests that have been shown to have ability to detect legal intoxication through field validation studies. They are the Horizontal Gaze Nystagmus , the Walk-and-Turn, and the One-Leg Stand. The results of these tests will be entered as evidence against you. But even under laboratory conditions, these tests have only been established to be accurate in predicting blood alcohol content above .10% from 65% to 77% of the time.

Standardized Field Sobriety Tests:
Horizontal Gaze Nystagmus
Horizontal gaze nystagmus (HGN) is an involuntary jerking of the eyeball which occurs naturally. This test theorizes that when a person is impaired by alcohol, nystagmus is exaggerated, and the alcohol-impaired person will have difficulty smoothly tracking a moving object. To administer this test, an officer asks the subject to watch a slowly moving stimulus, such as the tip of a pen. As the officer moves the object back and forth, the officer watches the subject’s eyes, looking for six standardized “clues,” up to three in each eye, of intoxication:

1.    Lack of smooth pursuit (eye cannot smoothly follow stimulus)
2.    Sustained and distinct nystagmus at maximum deviation (nystagmus longer than four seconds when eye is moved furthest from center)
3.    Onset of nystagmus before eye reaches 45 degrees

The presence of four or more clues is considered a failure of the test. The circumstances of a roadside administration, or a lack of training for the officer administering the test, can significantly affect and/or invalidate test results.

Walk-and-Turn
A subject is instructed to take nine steps along a straight line, walking heel-to-toe. After taking the steps, the subject must turn on one foot and return in the same manner in the opposite direction.
The officer looks for eight clues of impairment, specifically, if the subject being tested:

1.    Cannot keep balance while listening to officer’s instructions
2.    Begins before instructions are finished
3.    Stops walking
4.    Breaks the heel-to-toe walk by more than ½ inch
5.    Steps offline
6.    Raises arms more than six inches from side of body
7.    Takes an improper turn
8.    Takes an incorrect number of steps

One-Leg Stand
The subject is instructed to stand on one leg, with the other foot suspended approximately six inches off the ground and to count aloud by thousands (“One thousand-one,” “one thousand-two,” etc.) until instructed to put the foot down. The officer times the person for 30 seconds.
The officer looks for four clues of impairment, specifically if the subject being tested:

1.    Puts the raised foot down
2.    Uses arms to balance (raises them more than six inches from side)
3.    Sways
4.    Hops

Other Sobriety Tests:
Counting
The suspect is asked to count forwards or backwards, usually by ones or threes.
Signs of impairment include:

1.    Skipping letters
2.    Loss of concentration
3.    Slurred speech

This is not a particularly accurate or reliable sobriety test.

Finger to Nose
The subject stands, usually with the head tilted back and eyes closed, with arms stretched out to his or her sides. The subject then attempts to touch the tip of the index finger to his or her nose, first with one arm and then the other.
Signs of impairment include:

1.    Beginning before instructions are completed
2.    Swaying or staggering
3.    Using arms to balance
4.    Losing balance
5.    Inability to touch fingertip to nose

This test can be difficult to perform even when sober, without practice.

Reciting the Alphabet
The suspect is asked to recite the alphabet, sometimes backwards.
Signs of impairment include:

1.    Skipping letters
2.    Loss of concentration
3.    Slurred speech

This test is not particularly accurate, and may not be appropriate for suspects for whom English is not the primary language.

Chemical Testing Techniques
Despite all evidence to the contrary, if the officer decides a chemical test is justified, the testing can be a breathalyzer, urine test, or blood test. Frequently, the police will use a breathalyzer test for the initial screening. However, you are generally allowed the option of taking one of the other two tests, at your request.