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Making a DUI Arrest – Police Officers Look For These Signs Of Impairment

los angeles dui lawyerIf you’ve ever wondered what signs of impairment police offers look for in order to make a DUI arrest, you might be surprised. The National Highway Traffic Safety Administration (NHTSA) has specific criteria outlining probable cause for impairment. If you feel you’ve been wrongfully accused, it may be beneficial to review the lawful procedures specific to California law enforcement and consult a Los Angeles DUI attorney.

Phase I: Vehicle in Motion

Before the police lights start flashing and the siren sounds, the arresting officer will identify a moving violation that suggests intoxication. There are 24 infractions that indicate driving under the influence and lead quickly to an arrest. The most common are:

  • Weaving / Drifting
  • Swerving
  • “Hugging” or straddling a line
  • Stopping too far, too short, or too abruptly
  • Driving too slow (drunk drivers tend to overcompensate by driving below the speed limit)
  • Driving the wrong way down a one-way street
  • Driving without headlights at night
  • Improper turns (too fast, too wide, turning without a signal, etc.)
  • Noticeable focus such as a tight grip on the steering wheel or a lean-in toward the windshield
  • Braking upon seeing a patrol car
  • Failure to maintain consistent speed

Contrary to popular belief, police officers should not accuse a driver of impairment under the following circumstances:

  • Speeding
  • Broken headlight or tail light
  • Tinted windows

Phase II: Personal Contact

Upon interacting with you, the officer will make several observations to determine impairment and accuse you of DUI. However subjective they may be, even one of these “red flags” is reason enough to proceed with the third and final phase.

Physical Objects

  • Open/empty containers
  • Drugs or drug paraphernalia
  • Soiled clothing

Bodily Symptoms

  • Bloodshot eyes
  • Smell of alcohol on breath
  • Smell of marijuana on clothes or in vehicle


  • Slurred speech
  • Erratic behavior
  • Incoherent/inconsistent answers to questions
  • Anger/aggression
  • Failure to follow instructions or answer questions
  • Stumbling while exiting vehicle

Keep in mind, officers have the right to “quiz” or distract you to see if you can follow their orders easily and multi-task.

Phase III: Field Sobriety Test

Once you’ve exited the vehicle, you will most likely be subjected to one of four tests to measure your level of intoxication.

  1. Horizontal gaze: The officer will have you perform an exercise such as following a pen with your eyes to look for unusual eye movement or “clues” of intoxication. Four or more clues suggest a Blood Alcohol Concentration (BAC) between .04 and .08% or above.
  2. Walk and turn: This is a test used to determine coordination and balance. There are eight clues observed such as failure to follow instruction and losing balance; however, only two missed cues will result in failure.
  3. Single leg stand: The officer may require you to balance on one leg for thirty seconds while he or she observes signs of intoxication such as swaying or dropping the foot.
  4. Breath test: The most common tool used to identify intoxication is a breathalyzer. You will be instructed to breathe into an electronic device that produces a reading for BAC. Though it’s the most accurate method above all others, breathalyzers can and do produce faulty readings.

It’s important to understand an arrest can be made at any point during the above procedures. The choice is ultimately up to the officer and it’s not uncommon for law enforcement to arrest a sober person who may exhibit one or two signs of intoxication. If you’ve been arrested for DUI in Los Angeles, an attorney can advise you of your rights which include an understanding of standard protocol for DUI stops set forth by the NHTSA.

If you’ve been arrested for DUI in Los Angeles, contact Jon Artz to discuss your case in confidence.

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