At the conclusion of
this session, participants will be able to:
• Identify typical cues of
Detection Phase One
• Describe the observed cues
clearly and convincingly
The first task,
observing the vehicle in motion, begins when you first notice the vehicle,
driver or both. Your attention may be drawn to the vehicle by such things as:
• A moving traffic violation
• An equipment violation
• An expired registration or
inspection sticker
• Unusual driving actions, such as
weaving within a lane or moving at a slower than normal speed
• Evidence of drinking or drugs in
vehicle
If this initial
observation discloses vehicle maneuvers or human behaviors that may be
associated with impairment, you may develop an initial suspicion of DWI.
Based upon this
initial observation of the vehicle in motion, you must decide whether there is
reasonable suspicion to stop the vehicle. At this point you have three choices:
• Stop the vehicle.
• Continue to observe the vehicle.
• Alternatives to stopping the vehicle include:
• Delaying the stop/no stop
decision, in order to continue observing the vehicle
• Disregarding the vehicle
Common Symptoms
of Alcohol Influence
Blood Alcohol
Concentration
Slowed
ImpairedImpairedPoor Reaction Judgment Vision Coordination
and Standardized
Fie d Sobr ety Test ng
B. Initial
Observations: Visual Cues of Impaired Vehicle Operation (Automobiles)
Drivers who are
impaired frequently exhibit certain effects or symptoms of impairment. These
include:
• Slowed reactions.
• Impaired judgment as evidenced
by a willingness to take risks.
• Impaired vision.
• Poor coordination.
Common Symptoms
of Alcohol Influence (Cont.)
Blood Alcohol
Concentration
0.03 0.05 0.08 0.10
Slowed
ImpairedImpaired Poor Reaction Judgment Vision Coordination
Fie d Sobr
ety Test ng
This unit focuses on
alcohol impairment because research currently provides more information about
the effects of alcohol on driving than it does about the effects of other drugs
on driving. Remember that whether
the driver is impaired, the law enforcement detection process is the same, and
the offense is still DWI.
The common effects
of alcohol on the driver's mental and physical faculties lead to predictable
driving violations and vehicle operating characteristics. The National Highway
Traffic Safety Administration (NHTSA) sponsored research to identify the most common
and reliable initial indicators of DWI. This research identified 24 cues, each
with an associated high probability that the driver exhibiting the cue is
impaired. These cues and their associated probabilities are described in the
NHTSA publication,
The Visual
Detection of DWI Motorists.
They also are
discussed in Visual Detection of Driving While Intoxicated, a video
sponsored by NHTSA to assist law enforcement officers to recognize DWI
detection cues.
(ANACAPA
Sciences, DOT HS 808 654, 1997.)
The National Highway
Traffic Safety Administration sponsored research to identify the most common
and reliable initial indicators of DWI.
Research identified
100 cues, each providing a high probability indication that the driver is under
the influence.
The list was reduced
to 24 cues during three field studies involving hundreds of officers and more
than 12,000 enforcement stops.
Most Common and Reliable Initial Indicators of DWI
• Problems in maintaining
proper lane position
• Speed and braking problems
• Vigilance problems
• Judgment problems
Fie d
Sobr ety Test ng
The driving
behaviors are presented in four categories:
• Problems in maintaining proper
lane position
• Speed and braking problems
• Vigilance problems
• Judgment problems
Problems
Maintaining Proper Lane Position
• Weaving
• Weaving across lane line
• Drifting
• Straddling a lane line
• Swerving
• Almost striking object or
vehicle
• Turning with a wide radius
d Sobr ety
Test ng
There is a brochure
published by NHTSA that contains these cues. The title is “The Visual Detection
of DWI Motorists” DOT HS 808 677. The first category is: Problems in
maintaining proper lane position. [p=.50-.75]
• Weaving.
• Weaving across lane lines.
• Drifting.
• Straddling a lane line.
• Swerving.
• Almost striking object or
vehicle.
• Turning with a wide radius.
Speed and Braking
Problems
• Stopping problems
• Unnecessary acceleration or
deceleration
• Varying speed
• 10 mph or more under the
speed limit
d
Sobr ety Test ng
Speed and braking
problems. [p=.45-.70].
• Stopping problems (too far, too
short, or too jerky).
• Unnecessary acceleration or
deceleration
• Varying speed
• 10 mph or more under the speed
limit
Vigilance
Problems
• Driving without headlights at
night
• Failure to signal or signal
inconsistent with action
• Driving in opposing lanes or
wrong way on one way
• Slow response to traffic
signals
• Slow or failure to respond to
officer’s signals
• Stopping in lane for no
apparent reason
d
Sobr ety Test ng
The third problem is vigilance problems. [P=.55-.65]. This category
includes, but is not limited to:
• Driving without headlights at
night
• Failure to signal or signal
inconsistent with action
• Driving in opposing lanes or
wrong way on one way
• Slow response to traffic signals
• Slow or failure to respond to
officer’s signals
• Stopping in lane for no apparent
reason
Judgment Problems
• Following too closely
• Improper or unsafe lane
change
• Illegal or improper turn
• Driving on other than
designated roadway
• Stopping inappropriately in
response to officer
• Inappropriate or unusual
behavior
• Appearing to be impaired
Sobr
ety Test ng
Judgment problems.
[P=.35-.90].
• Following too closely
(tailgating)
• Improper or unsafe lane change
• Illegal or improper turn
• Driving on other than designated
roadway
• Stopping inappropriately in
response to officer
• Inappropriate or unusual
behavior (throwing objects, arguing, etc.)
• Appearing to be impaired
Post Stop Clues
• Difficulty with motor vehicle
controls
• Fumbling with driver license
or registration
• Difficulty exiting the
vehicle
• Repeating questions or
comments
• Swaying, unsteady, or balance
problems
• Leaning on the vehicle or
other object
• Slurred speech
• Slow to respond to
officer/officer must repeat
• Provides incorrect
information, changes answers
• Odor of alcoholic beverage
from the driver
Fie d Sobr
ety Test ng
The research also
identified 10 post stop cues. [P > .85].
• Difficulty with motor vehicle
controls
• Fumbling with driver license or
registration
• Difficulty exiting the vehicle
• Repeating questions or comments
• Swaying, unsteady, or balance
problems
• Leaning on the vehicle or other
object
• Slurred speech
• Slow to respond to
officer/officer must repeat
• Provides incorrect information, changes
answers
• Odor of alcoholic beverage from
the driver Explanation and illustration of the 24 detection cues.
Visual Cues of
Motorcycle Impaired Drivers
d Sobr ety
Test ng
C. Initial
Observations: Visual Cues of Impaired Vehicle Operation (Motorcycles)
Motorcycle
DUI Detection Guide Excellent Cues (50% or Greater Probability)
• Drifting during turn or curve
• Trouble with dismount
• Trouble with balance at a
stop
• Turning problems
• Inattentive to surroundings
• Inappropriate or unusual
behavior
• Weaving
Fie d Sobr
ety Test ng
Research has identified
driving impairment cues for motorcyclists.
(ANACAPA Sciences, DOT
HS 807 839, 1993.)
Excellent cues (50% or
greater probability).
• Drifting during turn or curve
• Trouble with dismount
• Trouble with balance at a stop
• Turning problems (e.g.,
unsteady, sudden corrections, late braking, improper lean angle)
• Inattentive to surroundings
• Inappropriate or unusual
behavior (e.g., carrying or dropping object, urinating at roadside, disorderly
conduct, etc.)
• Weaving
Motorcycle DUI Detection Guide Good cues (30 to
50% probability)
• Erratic movements while going
straight
• Operating without lights at
night
• Recklessness
• Following too closely
• Running stop light or sign
• Evasion
• Traveling wrong way
d
Sobr ety Test ng
Good Cues (30 to 50%
probability)
• Erratic movements while going
straight
• Operating without lights at
night
• Recklessness
• Following too closely
• Running stop light or sign
• Evasion
• Traveling wrong way
Relationship of
Visual Cues to Impaired Divided Attention Capability
Driving is a complex
task, composed of many parts:
• Steering
• Controlling accelerator
• Signaling
• Controlling brake pedal
• Operating clutch (if applicable)
• Operating gearshift (if
applicable)
• Observing other traffic
• Observing signal lights, stop
signs, other traffic control devices
• Making decisions (whether to
stop, turn, speed up, slow down, etc.)
• Many other things
In order to drive safely, a driver must be able to divide attention
among all of these various activities.
Under the influence of alcohol or many drugs, a person's ability to
divide attention becomes impaired.
The impaired driver tends to concentrate on certain parts of driving
and to disregard other parts.
• Alcohol has impaired ability to
divide attention.
• Driver is concentrating on
steering and controlling the accelerator and brake.
• Does not respond to the
particular color of the traffic light.
Some of the most significant evidence from all three phases of DWI
detection can be related directly to the effects of alcohol and/or other drugs
on divided attention ability.
D. Recognition and Description of Initial Cues
What do you see?
• Moving violation?
• Equipment violation?
• Other violation?
• Unusual operation?
• Anything else?
Phase
One: Task One Initial Observation of Vehicle Operation
Requires
the ability to:
• Recognize evidence of alcohol
and/or other drug influence
• Describe that evidence
clearly and convincingly
Standard
zed Fie d Sobr ety Test ng
Phase One: Task
One Initial Observation of Vehicle Operation
The task of making
initial observations of vehicle operation is the first step in the job of DWI
detection.
Proper performance
of that task demands two distinct but related abilities:
• Ability to recognize evidence of
alcohol and/or other drug influence.
• Ability to describe that
evidence clearly and convincingly.
It is not enough
that a police officer observe and recognize symptoms of impaired driving. The
officer must be able to articulate what was observed so that a judge or jury
will have a clear mental image of exactly what took place.
Improving the
ability to recognize and clearly describe observational evidence requires
practice.
It isn't practical
to have impaired drivers actually drive through the classroom.
The next best thing
is to use video to portray typical DWI detection contacts.
Procedures for
Practicing Cue Recognition and Description
• View DWI violation videos
• Take notes
• Testify
• Choose words carefully
• Provide as much detail as
possible
• Construct accurate image of
observations
• Critique testimony
E. Typical
Reinforcing Cues of the Stopping Sequence
After the command to
stop is given, the alcohol impaired driver may exhibit additional important
evidence of DWI.
Some of these cues
are exhibited because the stop command places additional demands on the
driver's ability to divide attention.
The signal to stop
creates a new situation, to which the driver must devote some attention, i.e.,
emergency flashing lights, siren, etc., demand and divert the subject's
attention.
Signal to stop
requires the driver to turn the steering wheel, operate the brake pedal,
activate the signal light, etc.
As soon as officer
gives the stop command, the subject's driving task becomes more complex.
If subject is under
the influence, the subject may not be able to handle this more complex driving
very well.
Session 5
Phase One: Veh cle n Mot on
Phase One: Task
Two
Observation of the Stop Requires the ability to:
• Recognize evidence of alcohol
and/or other drug influence
• Describe that evidence
clearly and convincingly
Test
ng
Phase One: Task Two Observation of the Stop
It is the officer's responsibility to capture and convey the additional
evidence of impairment that may be exhibited during the stopping sequence.
• Requires ability to recognize
evidence of alcohol and/or other drug influence.
• Requires ability to describe
that evidence clearly and convincingly.
• Recognition and
Description of Initial and Reinforcing Cues Procedures for practicing cue recognition and
description.
Course
Test your Knowledge
INSTRUCTIONS:
Complete the following sentences.
1. The Phase One tasks
are
2. Two common symptoms of
impairment are:
3. Alcohol impairs the
ability to among tasks.
4.Three cues reinforcing
the suspicion of DWI which may be observed during the stopping sequence are:
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