DWI Detection Phases  Vehicle in Motion Initial observation of vehicle Initial observation of vehicle Observation of stopping sequence Observation of stopping sequence  Personal Contact Observation of driver Observation of driver Observation of exit Observation of exit  Pre-Arrest Screening Standardized Field Sobriety Tests Standardized Field Sobriety Tests PBT PBT

Standardized Field Sobriety Tests  Designed to evaluate a persons divided attention ability  Three Standardized Field Sobriety Tests Horizontal Gaze Nystagmus Horizontal Gaze Nystagmus Walk and Turn Walk and Turn One Leg Stand One Leg Stand

Horizontal Gaze Nystagmus (HGN)  Three Standardized Clues Lack of Smooth Pursuit Lack of Smooth Pursuit Distinct and Sustained Nystagmus at Maximum Deviation Distinct and Sustained Nystagmus at Maximum Deviation Onset of Nystagmus Prior to 45 Degrees Onset of Nystagmus Prior to 45 Degrees  3 Clues x 2 Eyes=6 Possible Clues

HGN Validity  If FOUR or more clues are observed, the percentage of accuracy of the subject have a BAC of 0.08 or more is 88%  1997 San Diego Field Validation Study

Walk and Turn Test  Instruction Stage (2 Clues)  Walking Stage (6 Clues)

Walk and Turn Clues  Eight Standardized Clues Can’t Balance During the Instructions Can’t Balance During the Instructions Starts Too Soon Starts Too Soon Steps Off the Line Steps Off the Line Uses Arms for Balance (More than 6”) Uses Arms for Balance (More than 6”) Fail to Touch Heel to Toe (More than ½”) Fail to Touch Heel to Toe (More than ½”) Stops While Walking Stops While Walking Improper Turn/Lost Balance on Turn Improper Turn/Lost Balance on Turn Incorrect Number of Steps Incorrect Number of Steps

Walk and Turn Validity  TWO or more clues indicates a BAC at or above 0.08 with an accuracy of 79%  1997 San Diego Field Validation Study

One Leg Stand Test  Instruction Stage  Balance and Counting Stage

One Leg Stand Clues  Swaying  Uses Arms For Balance (More Than 6”)  Hopping  Puts Foot Down *Persons over 65 years of age or more than 50 pounds over weight may have difficulty with test

One Leg Stand Validity  TWO or more clues indicates a BAC of 0.08 or more with an accuracy of 83%  1997 San Diego Field Validation Study

Other Field Sobriety Tests  NOT Validated But Still Excellent Sources to View Impairment  Examples Romberg Balance Romberg Balance Finger to Nose Finger to Nose Alphabet Alphabet Counting Counting