How Do Police Officers Detect Drunk Drivers (DUI)?

Last Updated on August 2, 2023 by John Robinson

How Do Police Officers Detect Drunk Drivers

image: Pixabay

Florida laws define a DUI as when the driver’s blood alcohol level is at .08 or above. The possible consequences of a DUI increase with each consecutive offense and higher blood alcohol concentrations. These can include heftier fines every time, longer jail sentences, the impoundment of the vehicle, and an obligation to install an ignition interlock device.

Detecting a DUI (Driving Under The Influence)

While out on patrol, police officers will take certain actions to identify and arrest drivers that are drunk. They must not only detect these drivers, they must also gather sufficient evidence to conduct an arrest. To accomplish this, they must do the following.

Observe Vehicles in Motion

When a police officer observes a car that is moving erratically, they must decide whether this is a traffic violation and if they should stop the vehicle. Police officers have the authority to ask a driver to pull to the side of the road when reasonable suspicion exists that either a traffic violation or a crime has taken place or is taking place.

Some signs that officers might look for include:

  • Speeding 
  • Driving too slowly
  • Ignoring traffic signs
  • Swerving in and out of lanes
  • Almost hitting objects or other vehicles
  • Tailgating or following vehicles too closely
  • Expired vehicle registration

Once the driver has been pulled over for the above or any other reason, the officers will carefully observe the behavior of the driver to determine whether they may be under the influence of drugs or alcohol, or both.

The Officer Confronts the Driver

At this stage, the police officer and the driver come into contact for the first time.  Both vehicles have stopped, and the driver will be interviewed. Officers will also be on the lookout for clues such as:

  • Dirty or soiled clothing
  • Slurred speech
  • Confusion
  • Empty alcohol containers
  • The smell of marijuana or alcohol
  • Drugs or drug paraphernalia
  • Strong scents to try to mask odors
  • Handing over wrong documents when asked for license and registration
  • Fumbling around

During the interview process, police officers will not only ask questions, they will be paying close attention to the answers and the way they are delivered to detect signs of inebriation. The questions are quite straightforward and, under normal circumstances, the driver should have no difficulty giving a quick answer. These may be:

  • Do you know what day it is?
  • Can you tell me where you are coming from and where you are going?
  • Can you give me your complete address?
  • Have you been drinking or using drugs?

Pre-Arrest Screening

During this stage, the police officer will administer a field sobriety test to establish whether there is probable cause to issue an arrest for DUI. These tests measure the driver’s coordination, balance, and ability to understand and follow instructions. There are grades to this test, and these are not based on the officer’s “hunch.” The officer must observe specific cues or signs and decide whether to arrest the driver or release them and allow them to go on their way.

When you receive a DUI, you may feel scared or confused. You may be so intimidated by having to get out of your car that you may be afraid you might have acted in an unnatural way. However, you should always remember that you do have rights. There is more info here to understand your rights and what happens when you receive a DUI.

John Robinson
John Robinson

Howdy! I’m John Robinson from Levittown, New York. I am a mechanical engineer for 15 years and already had an established car repair company. I developed a personal relationship with cars since I was a kid. I always love the sounds and smell emitted by a car or truck and even at construction machinery. Since then I have been married but my love for cars only grew.