Driving Symptoms are the first piece of police evidence in a DUI/DWI case to attract an officer’s attention, unless an accident is involved. Many experienced prosecutors consider this to be the single most important piece of police evidence used to obtain a conviction.
Detection of a driver who is possibly driving under the influence (DUl) is usually initiated in one of several ways:
the direct observation of the individual’s driving symptoms while driving a vehicle.
a report from some other person of the individual’s driving
a call to the scene of an accident in which the driver is involved
a stop for a criminal or traffic violation
a stop at a sobriety checkpoint
Please click on a topic below to find out more about the different types of Driving Symptoms that cue an officer to pull a driver over:
- Problems in Maintaining Proper Lane Position
- Speed and Breaking Problems
- Vigilance Problems
- Judgment Problems
- The National Highway Traffic Safety Administration (NHTSA) Studies
Problems in Maintaining Proper Lane Position
Research shows that maintaining proper lane position can be a difficult task for a drunk driver, The DUI /DWl/ Drunk Driving cues related to problems in maintaining proper lane position include:
- Weaving – Weaving is when a vehicle is alternately moving towards one side of the lane and then back towards the other, This pattern of side-to-side, or lateral, movement is because the driver follows one steering correction by another.
- Drifting – Drifting is when a vehicle is moving in a generally straight line, but at a slight angle to the lane; as a result, the driver must make a steering correction as the vehicle approaches or crosses a lane line.
- Swerving – Swerving is when a vehicle has drifted out of proper lane position; as a result, the driver must make an abrupt turn away to avoid a previously unnoticed hazard.
- Turning With a Wide Radius – Turning with a wide radius is when a vehicle appears to drift to the outside of the lane, or into another lane, through the curve or while turning a comer.
- To close for comfort – To close for comfort is when a vehicle to passes unusually close to a sign, barrier, building, another vehicle (moving or parked), or other object.
In extreme situations all of these problems in maintaining proper lane position end up with the driver failing to correct in time to avoid an accident.
Speed and Braking Problems
Research shows that braking properly can be a difficult task for a drunk driver. The DUl / DWI / Drunk Driving cues related to braking problems include:
- Stopping too far from a curb or at an inappropriate angle,
- Stopping too short or beyond a limit line
- Jerky or abrupt stops.
- Stopping Beyond a Limit Line
Research shows showed that maintaining an appropriate speed can be difficult for a drunk driver, The DUl / DWl cues related to maintaining an appropriate speed include:
- Accelerate or decelerate rapidly for no apparent reason,
- Varying speed, alternating between speeding up and slowing down, or driven at a speed that is ten miles per hour or more under the limit.
Vigilance concerns a person’s ability to pay attention to a task or notice changes in surroundings. Research shows that alcohol impairs a driver’s vigilance. The DUl / DWI / Drunk Driving cues related to vigilance problems include:
Driving without headlights at night
Failure to signal a turn or lane change
Signaling inconsistently with actions, e.g. signaling left, but turning right
Driving in opposing lanes or crossing traffic
Failure to yield the right of way
Driving the wrong way on a one-way street
Slow response to traffic signals
Slow or failed response to officer’s lights, siren, or hand signals.
Stopping in a lane for no apparent reason.
A driver must constantly make decisions while operating a vehicle, but unfortunately even the smallest amount of alcohol can impair a driver’s judgment. The DUI / DWI /Drunk Driving cues related to judgment problems include:
- Following another vehicle too closely providing an unsafe stopping distance
- Improper or unsafe lane change with apparent disregard for other vehicles
- Illegal or improper turn -too fast, jerky, or sharp
- Driving on areas other than the designated roadway
- Stopping inappropriately in response to an officer
- Inappropriate or unusual behavior, e. g. urinating at the roadside, throwing something from the vehicle, etc,
The National Highway Traffic Safety Administration (NHTSA) Studies
The National Highway Traffic Safety Administration (NHTSA) has sponsored research identifying the 20 most common and reliable initial indicators of drunk driving along with the probability that the driver is intoxicated. For example, the chances are 65 out of 100 that a driver turning with a wide radius is intoxicated or has a blood-alcohol concentration of .08%. NHTSA research further indicates that the chances of a driver being intoxicated when multiple symptoms are observed can be calculated by adding 10% to the highest value among the cues observed. For example, the chances are 75 (65 + 10) out of 100 that a driver turning with a wide radius with their headlights off is intoxicated or has a blood-alcohol concentration of 08%.
65% -Turning with wide radius
65% -Straddling center or lane marker
60% -Appearing to be drunk
60% -Almost striking object or vehicle
55% -Driving on other than designated roadway
50% -Slow speed (more than 10 mph below limit)
50% -Stopping (without cause) in traffic lane
45% -Following too closely
45% -Tires on center or lane market
45% -Braking erratically
45% -Driving into opposing or crossing traffic
40% -Signaling inconsistent with driving action
35% -Stopping inappropriately (other than in lane)
35% -Turning abruptly or illegally
30% -Accelerating or decelerating rapidly
30% -Headlights off
The Visual Detection Guide of DUl / DWl Motorists
This guide, developed by the National Highway Traffic Safety Administration of the U.S, Department of Transportation, describes a set of behaviors that can be used by police officers to detect motorists who are likely to be driving while impaired.
The Use of Sobriety Checkpoints for Impaired Driving Enforcement
The National Highway Traffic Safety Administration’ 5 guidelines for sobriety checkpoints.