How Cops Spot a DUI

Police Officer writing a ticket for DUILaw enforcement officers are trained to look for certain driving patterns that may indicate a driver is under the influence of alcohol and or drugs.  According to the National Highway Traffic Safety Administration the three most common ways cops spot a DUI are; 1) wide turns, 2) straddling along the central marker between lanes, and 3) appearing to be drunk.

Officers must have a “reasonable cause” or a “reasonable suspicion” that a driver is violating the law in some manner to pull the driver over.  Reasonable cause and reasonable suspicion have no precise definition but it must be something supported by a collection of facts, for example an officer could see a car swerving and that minor moving violation would be enough for a stop.

An officer cannot pull someone over because they may have a hunch that person is DUI, they also cannot randomly pull drivers over in hopes they will find an individual that is DUI.

How Cops Spot a DUI

Here is the complete list of impaired driving signs cops are looking for when searching for DUIs.  The list, provided by the NHTSA, is in order from most common way a cop spots a DUI to least likely way.

  • Negotiating a wide turn
  • Straddling along the central marker between the lanes
  • Appearing to be drunk
  • Near misses or hitting either another vehicle or an object
  • Weaving between lanes
  • Driving off of designated highway
  • Swerving within the lane lines
  • Speeding over 10 mph above the designated speed limit
  • Questionable stops in traffic lanes
  • Tailgating
  • Drifting
  • Driving over center marker between lanes
  • Excessive braking
  • Driving against traffic
  • Questionable signaling
  • Delayed reaction to traffic signals
  • Inappropriate stopping or slowing
  • Illegal or unwarranted turns
  • Accelerating or slowing down quickly
  • Driving without headlights on

Interestingly enough, excessive speeding is not a sign of DUI.  Speeding requires quick reflexes and strong judgment, traits that are usually typical of a sober individual.  However if an individual is speeding and they also happen to be DUI, an officer would be able to investigate that individual for DUI even though they did not initially pull them over for DUI.

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