October 27, 2015

DWI Detection and Standardized Field Sobriety Testing Session 5 – Phase One: Vehicle in Motion Phase One: Vehicle in Motion

DWI Detection and Standardized Field Sobriety Testing
Session 5 – Phase One: Vehicle in Motion
Phase One: Vehicle in Motion
Initial Observation
of the Vehicle
in Operation
?
5-3
A. Overview: Tasks and Decision
Your first task in Phase One: Vehicle in Motion is to observe the vehicle in operation to
note any initial cues of a possible DWI violation. At this point you must decide whether
there is reasonable suspicion to stop the vehicle, either to conduct further investigation
to determine if the driver may be impaired, or for another traffic violation. You are not
committed to arresting the driver for DWI based on this initial observation, but rather
should concentrate on gathering all relevant evidence that may suggest impairment.
Your second task during phase one is to observe the manner in which the driver
responds to your signal to stop, and to note any additional evidence of a DWI violation.
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.
Notes:_______________________________________________
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HS 178 R5/13 3 of 19
DWI Detection and Standardized Field Sobriety Testing
Session 5 – Phase One: Vehicle in Motion
Phase One: Vehicle in Motion
Initial Observation
of the Vehicle
in Operation
Observation of
the Stop
Should I Stop
the Vehicle? ?
5-4
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.
• Disregard the vehicle.
Alternatives to stopping the vehicle include:
• Delaying the stop/no stop decision, in order to continue observing the vehicle
• Disregarding the vehicle
Whenever there is a valid reason to stop a vehicle, the officer should be alert to the
possibility that the driver may be impaired by alcohol and/or other drugs.
Once the stop command has been communicated to the suspect driver, the officer must
closely observe the driver's actions and vehicle maneuvers during the stopping
sequence.
DWI Detection and Standardized Field Sobriety Testing
Session 5 – Phase One: Vehicle in Motion Phase One:
Vehicle in Motion (Cont.)
Initial Observation
of the Vehicle
in Operation
Observation of
the Stop
Should I Stop
the Vehicle? ?
5-5
Sometimes, significant evidence of alcohol influence comes to light during the stopping
sequence. In some cases, the stopping sequence might produce the first suspicion of
DWI. Drivers impaired by alcohol and/or other drugs may respond in unexpected and
dangerous ways to the stop command.
Notes:_______________________________________________
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Notes:_______________________________________________
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HS 178 R5/13 4 of 19
DWI Detection and Standardized Field Sobriety Testing
Session 5 – Phase One: Vehicle in Motion
Common Symptoms of
Alcohol Influence
Blood Alcohol Concentration
Impaired
Vision
0.08
Poor
Coordination
0.10
Slowed
Reaction
0.03
Impaired
Judgment
0.05
5-6
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.
DWI Detection and Standardized Field Sobriety Testing
Session 5 – Phase One: Vehicle in Motion
Common Symptoms of
Alcohol Influence (Cont.)
Blood Alcohol Concentration
Impaired
Vision
0.08
Poor
Coordination
0.10
Slowed
Reaction
0.03
Impaired
Judgment
0.05
5-7
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.
Notes:_______________________________________________
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Notes:_______________________________________________
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HS 178 R5/13 5 of 19

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