The National Highway Traffic Safety Administration (NHTSA) created a list of various “cues” that help police officers determine where a driver might be under the influence of alcohol or drugs. These cues can be visually observed from a distance, specifically when law enforcement is following a suspected drunk driver.
The following are common types of visual cues police look out for to make a traffic stop:
- Difficulty maintaining proper lane position – Drivers who have trouble staying within their own driving lane or moving between lanes is an indication of intoxication. Common examples of this driving behavior include swerving, weaving across different lanes, drifting towards one side of the road, or making an extremely wide turn.
- Judgment issues – Since driving a vehicle involves making countless decisions, motorists must always be alert and properly judge speed and distance. When a person is under the influence, they are more than likely to take risks. Common examples of judgment issues include making erratic or unsafe lane changes, making illegal turns, driving off-road, or tailgating.
- Awareness problems – Being alert also involves noticing current road and traffic conditions, such as traffic signals and signs, as well as the flow of traffic itself. Intoxicated drivers lack the awareness to recognize these conditions. Common examples of awareness problems include delayed responses to traffic signals and signs, using the wrong turn signal to change lanes to make a turn, driving in the dark without turning on the headlights, or driving in the wrong direction.
- Acceleration and braking trouble – Difficulties judging distance and speed can lead to speeding and braking issues. Common examples of acceleration problems include speeding at least 10 mph more than the posted speed limit, sudden acceleration for no reason, and failure to maintain a consistent speed. Common stopping problems include stopping well before the intersection or crosswalk, making jerky or short stops, or stopping at an odd angle.
Making any of these movements or committing a traffic stop is considered reasonable suspicion, which is enough for law enforcement to make a traffic stop.