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How Police Spot Intoxicated Drivers


The National Highway Traffic Safety Administration (NHTSA) has created a list consisting of several types of visuals cues for detecting drivers who are impaired by alcohol or drugs. These cues were determined as a result of a study involving interviews by police officers and extensive research. This list helps law enforcement spot motorists who are likely driving over the legal limit.

According to the NHTSA, the following are the four primary signs of driving under the influence of alcohol:

  • Inability to maintain proper lane position – Issues with staying within a driving lane on the road is often an indicator of intoxicated driving. Common examples of these problems include swerving within the lane, weaving through multiple lanes in a reckless manner, drifting towards one side of the highway or road, straddling the center line or side of the road, or making turns that are too wide.
  • Braking and speeding problems – Drunk drivers experience difficulties judging distance and speed while operating a vehicle, which results in acceleration and braking issues. Common braking problems include making stops well before or beyond an intersection, making jerky stops, and stopping at odd angles and far away from curbs. Common acceleration issues include failing to drive at a consistent speed, driving well below or beyond the posted speed limit, and sudden acceleration and braking for no reason.
  • Awareness issues – If a person fails to remain vigilant and doesn’t notice traffic conditions, such as traffic lights and the flow of traffic itself. Common awareness problems include slowly responding to traffic lights and signs, driving in the wrong direction, using the wrong turn signal when changing lanes or making turns, and driving at night without turning on the headlights.
  • Judgment difficulties – Every time a person drives a vehicle, he/she must constantly make judgments on the road, which is why it is imperative to always remain alert. Drunk drivers often take more risks than sober, careful motorists. Common indicators of judgment issues include tailgating, making illegal turns, making unsafe lane changes, and driving off-road.

When the police notice any one of these signs, they are able to establish “reasonable suspicion” to make a lawful traffic stop. Once the driver is pulled over, common signs of driver intoxication include the smell of alcohol coming from the driver or within the vehicle, open alcohol containers, delayed response to questions, slurred speech, and poor motor skills.

If you have been arrested for an OWI in Wisconsin, contact our Milwaukee criminal defense attorney at the Law Offices of Christopher J. Cherella and schedule a free consultation today.

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