October 29, 2015

DWI Detection and Standardized Field Sobriety Testing Session 7 – Phase Three: Pre-Arrest Screening • Six maximum clues

DWI Detection and Standardized Field Sobriety Testing
Session 7 – Phase Three: Pre-Arrest Screening
Six maximum clues
Maximum three clues per eye
77% accurate detecting subjects
≥ 0.10 BAC
Nystagmus Indications
7-9
• When the HGN test is administered always begin with subject's left eye. Each eye is
examined for three specific clues.
• As the eye moves from side to side, does it move smoothly or does it jerk noticeably?
(As people become impaired by alcohol, their eyes exhibit a lack of smooth pursuit as
they move from side to side.)
• When the eye moves as far to the side as possible and is kept at that position for four
seconds, does it jerk distinctly? (Distinct and sustained nystagmus at maximum
deviation is another clue of impairment.)
• As the eye moves toward the side, does it start to jerk prior to a 45 degree angle?
(Onset of nystagmus prior to 45 degrees is another clue of impairment.)
• As a person's blood alcohol concentration increases it is more likely these clues will
appear.
• The maximum total number of clues is six. The maximum number of clues that may
appear in one eye is three.
• The original research was conducted by the Southern California Research Institute
(SCRI) and used to develop the initial curriculum showing this test was 77% accurate
at detecting subjects at or above a 0.10 BAC.
Notes:_______________________________________________
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HS 178 R5/13 6 of 26
Source: DWI Detection and
Standardized Field
Sobriety Testing
March 2013 Edition

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