Post on 26-Feb-2023
9/28/2018
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DUI Hot TopicsMiriam Norman, TSRP
HGN as Evidence of Impairment - How to Use This Evidence in Trial
Widmark’s Equation- How to Use This Evidence in Trial
Observable Signs of Impairment-Using Visual Exhibits in Trial
Lui Confrontation Briefing-How to Use the Reviewer or Supervisor in
Trial
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HGN as Evidence of ImpairmentHow to Use This Evidence in Trial
HORIZONTAL GAZE NYSTAGMUS
Alcohol and certain other drugs cause this phenomenon.
Drug categories: Depressants, Inhalants, Dissociative
Anesthetics (PCP), and also caused by Brain Stem Trauma
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Acquired Anticipatory (Induced)
Arthrokinetic (Induced, Somatosensory)
Associated (Induced, Stransky’s)
AudioKinetic(Induced)
Bartel’s (Induced)
Brun’s Centripetal Cervical (NeckTorsion, Vestibular-Obasilar, Artery Insufficiency)
Circular/Elliptic/Oblique
Congenital (Fixation, Hereditary)
Convergence
Convergence Invoked
Disassociated, Disjunctive
Downbeat Drug Induced (Barbituate, ow Tie, Induced)
Epileptic (Ictal) Flash induced
Gaze-Evoked (Deviational, Gaze-Paretic, Neurasthenic, Seducible, Setting-in)
Horizontal Induced (provoked) Intermittent Vertical Jerk Latent/Manifest Latent (Monocular Fixation, Unimacular)
Lateral Medullary Lid Miner’s (Occupational) Muscle Paretic (Myasthenic)
Optokinetic (Induced, Optomotor, Panoramic, Railway, Sigma)
Optokinetic After-Induced (Post-optokinetic, Reverse Post Optokinetic)
Penduar (Talantropia Periodic/Aperiodic Alternating
Physiologic (End Point/Fatigue)
Pursuit After Induced
Pursuit Defect Pseudo Spontaneous
Rebound Reflelx (Baer’s) See-Saw Somatosensory Spontaneous Stepping Around
Torisional Uniocular Upbeat Vertical Vestibular (Caloric, Compensatory, Compression, Positional/Alcohol, Pseudo Caloric)
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47 Types of Nystagmus!
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47 Types of Nystagmus!
• Vestibular Nystagmus:
• Rotational Nystagmus (occurs when the person is spun around or rotated rapidly causing the fluid in the inner ear to be disturbed); Post rotational Nystagmus (closely related to rotational nystagmus; once the spinning stops, the fluid in the inner ear will remain disturbed for a period of time).
• To illustrate rotational and post rotational nystagmus, swirl a glass of water several times. Stop swirling the glass, the water will continue to spin for a short period of time.
• Neither rotational nystagmus nor post rotational nystagmus will interfere with the HGN test because of the conditions under which they occur.
• Caloric Nystagmus- occurs when fluid motion in the canals of the vestibular system are stimulated by temperature as by putting warm water in one ear and cold ear in the other.
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Examples of Other Forms of NystagmusPost-Rotational Caloric
Examples of Optokinetic Nystamus and HGNOptokinetic Nystagmus HGN
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47 Types of Nystagmus!
• Optokinetic Nystagmus- occurs when the eyes fixate on an object that suddenly moves out of sight, or then the eyes watch sharply contrasting moving images. (e.g., strobe lights, rotating lights, rapidly moving traffic, cell phone screens as they scroll down.)
• “During the Horizontal Gaze Nystagmus test, the suspect is require to fixate the eyes on a penlight, pencil or similar object that moves in accordance with the HGN testing procedures, thus optokinetic nystagmus will not occur. The movement of the stimulus and the fixation on the stimulus by the subject precludes this form of nystagmus from being observed by the officer.”
• Physiological Nystagmus is a natural nystagmus that keeps the sensory cells of the eye from tiring. Most common form of nystagmus, but these tremors are generally too small to be seen and invisible to the naked eye.
HGN as Evidence of Impairment!
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How Will You ExplainThis Evidence to the JURY?
TALKING ABOUT HGN In Trial
• HGN: • Involuntary jerking of the eyes occurring as the eyes gaze towards the
side• Readily noticeable when a person is impaired• Not something that the person is aware of or can control
• Give an example:• Windshield wipers• Marble on smooth/sand surface• Sprinklers
§HGN: oInvoluntary jerking of the eyes occurring as the eyes gaze towards the sideoReadily noticeable when a person is impairedoNot something that the person is aware of or can control§Give an example:oWindshield wipersoSprinklers
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Eye Movements & DrivingScanning RoadwayScanning Roadway
35-45 deg35-45 deg
40-60 deg40-60 deg
Eye Movements & DrivingEye Movements & DrivingViewing in MirrorsViewing in Mirrors
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Defense Challenges to HGN• The officer is not an optometrist!!!!üYou do not need to be; we are trained to differentiate between HGN
and other types of nystagmus. • Lots of different types of nystagmus!• END POINT NYSTAGMUS • FATIGUE NYSTAGMUS üWe are trained to differentiate between HGN and other forms of
nystagmus; the process of HGN ensures that all other external causes of nystagmus are eliminated.
• Post-rotational (crash) was the nystagmus seen. • It was cold out and the window was down; thus caloric nystagmus
was seen! üReally…. No.
Defense Challenges to HGN§ The speed of each pass.ü“Approximately”üWatch your video and time it!
§ The stimulus is too far or too close.ü“Approximately 12-15 inches”
§ Insufficient number of passes.üPause between the equal tracking (medical checks) and lack of
smooth pursuit. üAmount of time stimulus held at maximum deviation. (At least 5
seconds to avoid seeing end point nystagmus, no longer than 29 seconds to avoid seeing fatigue nystagmus). üDistinct and sustained nystagmus at maximum deviation.
NHTSA Manual VIII-5-7
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Defense Challenges to HGN
§Did not testify to checking for each clue 2x
§Overhead lights of patrol car or passing traffic caused nystagmus:üNot optokinetic nystagmusüEliminated because focusing on the stimulus
§Angle of onset - did you have a protractor to estimate 45°??:ü12 to 15 out; 12 to 15” over! üStill see some white in the eyes NHTSA Manual VIII-5-7
Widmark’s Equation v. Retrograde Extrapolation
How to Use This Evidence in Trial
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Retrograde Extrapolation
Thanks to alcoholism.about.com
Retrograde Extrapolation• Used to estimate an ethanol level at an earlier
time
BAC (t+n) = BAC + (0.015 g/100 mL/hr x n hours)BAC (2 hr) = 0.07 + (0.015 g/100 mL/hr x 2 hr)BAC (2 hr) = 0.07 + (0.03)
• ***Use with caution***: multiple conditions must be met to use this
Burn-Off Range:
.01 / hour Avg: .015 / hour .02 / hour
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Retrograde Extrapolation
• Some ‘conditions’:• Post absorptive• Starting / known value > 0.02 g/100 mL (or g/210 L)• Time extrapolating to is also post absorptive
• Thanks to alcoholism.about.com
Widmark’s Equation
• Used to estimate a BAC from a given number of drinks OR estimate
a number of drinks from a BAC. • Need: weight, gender, and number
or drinks or BAC.
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Widmark’s Equation
BAC = # x oz x % x 5.2 / wt x ρ
# = number of standard drinksoz = size of each drink% = percent alcohol per drink5.2 = constant, unified conversion for imperial to metric units
wt = weight of person, in poundsρ = water distribution coefficient (male ~ 0.68, female ~ 0.55)
How should you use this in trial??? With whom???
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Observations and Signs of ImpairmentHow to Use This Evidence in Trial
Defendant’s Signs of ImpairmentEyes Red, Dilated with Droopy Eyelids
Car Crashed into Ditch
Slow Deliberate Speech
Difficulty presenting ID card from her wallet
Lack of Convergence, Eyelid Flutters Unable to remember tasks
Walk and Turn Clues
Marijuana and Pipe Found
Admits to 2 glasses of wine prior to driving
Admitted to Smoking Marijuana
Finger to Nose Test
Urine Contained THC MetabolitesPoor balance
Below Normal Blood Pressure
Leg Tremors
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CREDIBILITY OF THE WITNESSYou are the exclusive judges of the credibility of the
witnesses.
Truth or Fiction?
Inconsistent Statements
Interest in Outcome?
Bias or Motive
Effects of Alcohol? Ability to Recall
Believable or Not
Substance of Testimony
Manner While Testifying
Conduct and AttitudeConduct and Attitude
Manner While Testifying
Truth or Fiction?
Substance of Testimony
Believable or Not
Ability to RecallEffects of Alcohol or Drugs?
Bias or Motive
Inconsistent Statements
Interest in Outcome? Credibility?
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Your Analyst Is Unavailable… Understand the Issues!
Who will you potentially call as a witness?