The Walk and Turn Test
Proper Administration: In administering the Walk and Turn evaluation the officer:
- starts by having the driver assume the heel-toe position;
- tells the driver that this position is to be held” while the instructions are given;” (get the idea?”)
- If, while giving these instructions, the subject moves or steps off this stance, the officer stops and tells the driver to resume the position before going on;
- tells the driver that he should take 9 heel-to-toe steps down some real or imaginary line, to turn in a series if small steps, and then demonstrate the steps and the turn;
- tells the driver to keep the his arms at the sides, to watch the feet, to count the steps aloud, and to keep walking until the test is completed;
- asks the driver whether he understands; and, if not, re-explain and re-demonstrate.
- Tells the driver to begin;
- allows the subject to resume from the point of interruption, and not from the beginning, should the subject stagger or stop.
Standardized Clues: There are eight clues that officers are trained to look for as validated indicators of intoxication:
- Losing balance during instructions (try it sober!)
- Begins walking before instructed to do so
- Stops after told to start walking
- Misses heel-to-toe while walking by a one-half inch or more
- Raises arms (at least six inches or more) while walking
- Steps off the line
- Makes the turn improperly. (it seems that no one gets this right!)
- Takes the wrong number of steps
Standardized Scoring: A point is to be given for each clue shown by the driver. Scoring 2 or more clues is indicative of impairment.
The One Leg Stand
Proper Administration: The one leg stand requires that the officer to:
- tell the driver to stand with feet together, and arms at side;
- tell the driver not to start the test until instructed to do so;
- ask the driver if he understands;
- tell the driver to stand on one foot, and hold the other leg out ward toes pointed and held about 6 inches above the ground. demonstrate the stance;
- tell the driver to count from 1 to 30, by thousands;
- then demonstrate the count to the driver, for several seconds;
- ask the driver whether he understands; if not, re-explain and re-demonstrate. tell the driver to begin
After the test begins the officer should not interrupt the driver if driver stops or puts a foot down, but instruct to continue from that point and continuing the count where the driver stopped.
Standardized Clues: Officers look for recognized certain “validated clues” as signs of impairment.
- Putting the foot down
- Raising the arms from the sides 6 inches or more
Standardized Scoring: The officer is taught to be objective in the scoring. The driver should receive one point for each clue of intoxication. Once again, there should be only one point per clue regardless of the number of times that clue is shown.
The Horizontal Gaze Nystagmus Test (follow my finger)
Horizontal Gaze Nystagmus is medical condition that involves an involuntary reaction of the muscles that control eye movement resulting in “twitching or jerking” of the eye. It is not caused by alcohol but alcohol is known to cause it to be more apparent when an examination of the eye is conducted and the subject has consumed enough alcohol to affect those particular muscle groups. This jerking of the eye is measured by conducting three examinations.
- The officer tries to measure the angle of onset of the nystagmus. This is the angle at which the eye begins jerking
- The officer tries to determine whether the nystagmus becomes distinct if the eye is moved to its maximum limit
- The officer will look for a lack of smooth pursuit; that is, the eye jumps or jerks rather than following a moving object smoothly
Proper Administration: The officer is instructed to give these instructions:
- The officer will hold the “stimulus” (pen, penlight) 12-15 inches in front of the driver’s face;
- keep the tip of the stimulus slightly above the driver’s eyes;
- the officer should try to move the stimulus smoothly;
- the officer should always check for all 3 clues in both eyes;
- The officer will check twice in each eye for the clues. The sequence should be: lack of smooth pursuit; distinct nystagmus at maximum deviation; onset of nystagmus prior to 45 degrees.
Standardized Clues: The clues recognized by NHTSA as valid indicators of horizontal gaze nystagmus are as follows:
- Lack of smooth pursuit
- Distinct nystagmus at maximum deviation
- Onset of nystagmus prior to 45 degrees
Standardized Scoring: One clue is to be given for each indicia manifested by the driver. There are six clues (three for each eye) of HGN, a score of 4 is considered unsatisfactory