Chapter 12 - DUI Traffic Stops - Unit 2 Flashcards
DUI Investigation Detection Phase One:
vehicle in motion—observing the way the driver operates and stops the vehicle
DUI Investigation Detection Phase Two:
personal contact—observing and speaking with the driver face to face
DUI Investigation Detection Phase Three:
pre-arrest screening—administering the SFSTs to the driver to determine if there is probable cause to arrest for DUI
Divided attention
the ability to concentrate on two or more tasks at the same time.
Horizontal gaze nystagmus (HGN)
an involuntary jerking that occurs as the eyes move toward the side
Psychophysical test
a divided attention test that measures a person’s ability to perform both mental and physical tasks at the same time.
Nystagmus
an involuntary jerking of the eyes
When you administer the HGN test give the following instructions:
- “I am going to check your eyes.” (“Do you wear glasses or contacts?” If they are wearing glasses ask them to remove their glasses.)
- “Stand with your feet together (heels and toes) and your hands down at your side.” (The subject may also be seated.)
- “Keep your head still and follow this object with your eyes only.”
- “Do not move your head.”
- “Do you understand the instructions?”
While administering the HGN test…
have the driver follow the motion of a small object with their eyes only. Position the object about 12–15 inches from the driver’s nose and slightly above their eye level. Begin with the driver’s left
eye, then the right, and examine each eye twice.
Lack of smooth pursuit
Lack of smooth pursuit occurs when the eye of an impaired driver jerks or bounces as the eye follows a smoothly moving stimulus
Distinct and sustained nystagmus at maximum deviation
occurs when the gaze of the eye has moved as far as it can go toward the shoulder, and no white is visible at the outside of the eye. You can observe the eye jerk when it is held at maximum deviation for a minimum of four seconds.
Vertical gaze nystagmus (VGN)
the involuntary jerking of the eyes as they move upward and are held at maximum deviation for a minimum of four seconds
HGN clues
The maximum number of clues that may appear in one eye is three. The maximum number of total clues observed is six.
Walk and turn instructions
- “Place your left foot on the line.” (real or imaginary)
- “Place your right foot on the line ahead of your left foot with the heel of your right foot against the toe of your left foot.”
- “Place your arms down at your sides.”
- “Maintain this position until I have completed the instructions. Do not start to walk until told to do so.”
- “Do you understand the instructions so far?” Make sure the driver indicates that they understand.
Walking Stage instructions
- “When I tell you to start, take nine heel-to-toe steps on the line, turn, and take nine heel-to-toe stepsback.” (Demonstrate a minimum of three heel-to-toe steps.)
- “When you turn, keep your front foot on the line, and turn by taking a series of small steps with the other foot, like this.”
- “While you are walking, keep your arms at your sides, watch your feet at all times, and count your steps out loud.”
- “When I tell you to begin, take nine heel-to-toe steps down the line. On the ninth step, keep your forward / front foot on the line, and take a series of small steps to turn around. Return nine heel to-toe steps back down the line.” (Demonstrate.)
- “While walking, watch your feet at all times, keep your arms at your side, and count your steps out loud. Once you begin, do not stop until the exercise is completed.”
- “Do you have any physical injuries or limitations that would keep you from completing this test?” (If the answer is yes, move on to the next test and record their answer in your notes.)
- “Do you understand the instructions?” Make sure the driver indicates that they understand.
- “Begin and count your first step from the heel-to-toe position as ‘One.’ ”
