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<< Continued From Page 2 SCORING You should look for three signs of intoxication in each eye. Give one point for each item checked for a maximum of six points. 1) Onset of alcohol gaze nystagmus in the right eye occurs before 45 degrees. Do not score this item unless some white is visible on the outside of the right eye (closest to the ear) at the point of onset. 2) Nystagmus in the right eye when moved as far as possible to the right is moderate or distinct. Do not score this item if you only see the faint jerking that occurs at the onset point. 3) The right eye cannot follow a moving object smoothly. If you score this item, be sure that the jerkiness was not due to your moving the object in a jerky manner. 4) Onset of alcohol gaze nystagmus in the left eye occurs before 45 degrees. If you score this item, be certain that some white is visible on the outside of the left eye (closest to the ear) at the point of onset. 5) Nystagmus in the left eye when it is moved as far as possible to the left is moderate or distinct. 6) The left eye cannot follow a moving object smoothly. If a suspect scores four or more points out of the six possible on this test, classify his BAC as above 0.10 percent. Using this criterion you will be able to correctly classify about 77 percent of your suspects with respect to whether they are drunk or sober. That probability was determined during limited laboratory and field testing and is given simply to help you weigh the various sobriety tests in this battery as you make your arrest decision. TEST CONDITIONS Very few test conditions will affect gaze nystagmus. Most of the test requirements given in this Manual are designed to make the observation of nystagmus as easy as possible for the officer doing the testing. Nystagmus can he observed directly and requires no special equipment. You will need something for the suspect to follow with his eyes, but this can be as simple as the tip of your index finger. Officers who use this test frequently have the suspect follow a penlight. The object used should be held about eye level, so that the eyes are wide open when they look directly at it. It should be held about 12 to 15 inches in front of the eyes for ease of focus. |
Copyright 2000 - 2008 |
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Glasses should be removed since they may block your view of the suspect's eyes. In addition, hard contact lens may restrict the boundaries of movement of the eyes. If this appears to happen, you may still conduct the tests. You should be aware that this factor may affect the reliability of this test and you should record this condition in your field notes. In addition to the preceding material, counsel should also consider the research on which NHTSA relied in determining that nystagmus was a relatively reliable field sobriety test. One of those studies is found in a NHTSA brochure authored by V. Tharp entitled Psychophysical Tests For DUI Arrests (DOT HS-8-01970). Although recommending the test, the author mentions the following additional procedures (emphasis is added by the author of this text to indicate potential sources for cross examination): The person being tested should remove all corrective lenses; glasses may impede an officer's view of the eyes and hard contact lenses tend to limit the lateral movement of the eyes (which might prohibit the recognition of borderline cases). The occurrence of nystagmus is not affected by visual acuity. The stimulus should be positioned above the eyes, in order to elevate them and reduce squinting, and about 15 inches away from the eyes. At night if the street lighting is not adequate, a penlight should be used to illuminate the face and eyes. The officer should move the stimulus at least twice in each direction, looking at the eye on the side of the head to which lie is moving the stimulus. The suspect must keep his/her head still. The officer's flashlight makes a good chinrest for suspects who persist with head movements. The first movement in each direction should be slow (i.e., at about 10 degrees per second), while the second movement should be somewhat faster (i.e., at about 20 degrees per second). During the first movement of the stimulus in each direction, the officer should look for the onset of nystagmus. When he first detects a slight jerking, he should stop moving the stimulus to make sure that the jerking continues. If the nystagmus stops, then the officer has not found the point of onset and he should continue his examination. When the officer finds the onset point, he should determine whether or not it occurs before 45 degrees with some of the conjunctiva (i.e., the white of the eye) showing. The 45 degree angle was chosen as a criterion because it is close to the expected onset point for a BAC of 0.10 percent and because it is easy to estimate. The 45 degree angle splits the right angle that runs from the tip of the nose to the center of the head to the middle of the ear. Since some individuals cannot deviate their eyes more than 45 degrees, some white of the eye must show to ascertain that nystagmus is not occurring at the most extreme deviation for that individual. Smooth pursuit eye movements should also be examined by a police officer at roadside, although this is the least reliable of the three signs. We recommend that the second movement of the stimulus in each direction he at about 20 degrees per second, while the officer looks for impaired smooth pursuit. The officer must be careful to move the stimulus smoothly to be sure that impaired pursuit is not due to his manner of moving the stimulus. What a police officer will see as the BAC increases is: (1) at a BAC of 0.08 percent-0.l0 percent impaired smooth movements interrupted by small jerks or saccades; (2) at a BAC in the range of 0.15 percent to 0.20 percent the eye movements will be characterized by much bigger saccades; (3) at high BACs (e.g., above 0.25 percent) most people cannot track at all. |
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San Francisco DUI Laws and Lawyers is provided as an information center for those facing criminal charges in San Francisco, San Mateo County, Marin County, Napa County, Sonoma County, Alameda County and Contra Costa County. It is also intended to counter the growing influence of radical groups pressuring courts, prosecutors and legislators for more unfair DUI laws, increasingly harsh punishment, more erosion of our Constitutional protections, and ultimately a return to the days of prohibition. The website for the National Motorists Association presents views on such important DUI-DWI issues as the constitutionality of roadblocks, reliance upon questionable breath tests, officer-administered license suspensions, and inappropriate penalties in drunk driving cases. |
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