Category Archives: DUI Field Sobriety Tests

Horizontal Gaze Nystagmus • Walk & Turn • One Leg Stand

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 horizontally (back and forth), the officer watches the subject’s eyes as they follow the object, watching for six standardized “clues,” up to three in each eye, to intoxication:

Lack of smooth pursuit (eye cannot smoothly follow stimulus).
Sustained and distinct nystagmus at maximum deviation (nystagmus longer than 4 seconds when eye is moved furthest from center (approximately 60 degrees)).
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.

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:

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

The subject is instructed to stand on one leg, with the other foot suspended approximately six inches off the ground and count aloud by thousands (“One thousand-one”, “one thousand-two”, etc.) until instructed to put the foot down. The officer times the person for thirty seconds.

The officer looks for four clues of impairment, specifically if the subject being tested:

Puts the raised foot down.
Uses arms to balance (raises more than 6 inches from side).
Sways.
Hops.

Finger to Nose • Counting • Reciting the Alphabet

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

Signs of impairment include:

Beginning before instructions are completed
Swaying or staggering
Using arms to balance
Losing balance
Inability to touch fingertip to nose
This test can be difficult to perform even when sober, without practice.

The suspect is asked to count forwards or backwards, usually by ones or threes.

Signs of impairment include:

skipping letters
loss of concentration
slurred speech
This is not a particularly accurate or reliable sobriety test.

The suspect is asked to recite the alphabet, sometimes backwards.

Signs of impairment include:

Skipping letters
Loss of concentration
Slurred speech
This test is not particularly accurate, and may not be appropriate for suspects for whom English is not the primary language.