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What signs of impaired driving do police look for?

On Behalf of | Nov 30, 2023 | DUI |

After a traffic stop, police officers may gather evidence that a driver was impaired. This evidence could include the fact that the driver failed a field sobriety test, for instance, or that they blew over the legal limit on a breath test.

However, police officers need to have a valid reason to stop the car in the first place. They need to see signs of potential impaired driving (or other legal violations) to initiate an initial traffic stop, otherwise the evidence gathered during that stop may be suppressed at trial. In most situations, police officers are not allowed to make random stops, but have to observe a reason to pull motorists over first.

Signs of impairment

As such, law enforcement officers are trained to look for various signs of impaired driving when monitoring motorists on the road. Some common indicators that a motorist is impaired include:

  1. Erratic or unsafe driving behavior: This includes swerving, weaving between lanes, making abrupt lane changes, tailgating and driving at inconsistent speeds. A driver may be pulled over for straddling the centerline, with two wheels on either side, or for changing lanes without a blinker.
  2. Poor coordination and motor skills: Difficulty in maintaining proper lane position, problems with braking or stopping, delayed responses to traffic signals or signs and trouble with maintaining a steady speed. When a driver doesn’t react the same way as traffic around them, it could be an indicator of impairment.
  3. Lack of awareness: Inattentiveness to surroundings, failure to notice traffic signals, signs or other vehicles. A driver may fail to proceed at a green light, for example, or may run a stop sign that they never noticed.
  4. Unusual behavior: Aggressive behavior or unusual driving decisions that could indicate a driver is impaired. Many instances of road rage are spurred by alcohol, for instance, because drivers aren’t thinking rationally.

It’s important to remember that these signs or symptoms, on their own, may not conclusively prove impairment. A driver who is distracted by a crying child may make similar mistakes to an impaired driver, for instance, despite being completely sober. But these signs can raise suspicion and prompt law enforcement to conduct further tests, such as breathalyzer tests or blood tests, to determine a driver’s level of impairment accurately. They also serve as justification for the traffic stop, opening the door for the police to seek other evidence.

Those who find themselves facing charges need to understand exactly what accusations they’re facing, what criminal defense options they have and what steps to take next, as even strong evidence of impairment during a stop may be suppressed at trial if the stop itself was unlawful.