How Police Look for Drunk Drivers

The California Highway Patrol, in collaboration with local law enforcement agencies throughout Orange County is on a mission to nab drunk drivers. And through the use of DUI checkpoints, saturation patrols, and frequenting areas with a high concentration of drunk drivers (areas near bars and nightclubs), law enforcement is doing its best to keep drunk drivers off the roads.

So, how does law enforcement look for drunk drivers? What tools do they use? They do it through a process known as “DUI detection.” The National Highway Traffic Safety Administration (NHTSA) defines DUI detection as the process where law enforcement gathers evidence to determine if a suspect should be arrested for driving under the influence. According to the NHTSA, there are three phases of DUI detection:

  1. When the vehicle was in emotion.
  2. The officer’s personal contact with the driver.
  3. The “pre-arrest” screening of the suspect.

When a law enforcement officer suspects a driver is under the influence of alcohol or drugs, first the officer needs to establish evidence and reliable facts before they can ask the driver to submit to the standardized field sobriety tests.

Officers are trained to look for 24 specific queues while a vehicle is in motion. These 24 queues indicate that a driver may be intoxicated, and they include: weaving, swerving, straddling the lane, drifting, driving without the lights on at night, almost striking another vehicle, and tailgating.


What was the officer’s contact with the suspect like? This is important because it’s used to determine whether or not the officer asks the suspect to step outside of the vehicle. In these situations, officers are looking for indicators of intoxication, such as bloodshot eyes, the odor of alcohol on the driver’s breath, abusive language, alcohol containers, and slurred speech. Usually, the initial face-to-face contact will provide the officer an indication if the driver is impaired.


Finally, the officer decides if there is probable cause to arrest the suspect for DUI. In this phase, the officer’s first task is to administer the field sobriety tests. The second phase is to have the suspect take a preliminary breath test or PAS test.

Related: Does a DUI Show Up on Background Checks?

Did you go through these phases and were you ultimately arrested for DUI? Just because the officer decided to arrest you, it doesn’t mean that you have to be convicted. Learn how to fight your DUI charges by contact the Law Offices of Virginia L. Landry, Inc. today!

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