Skip to Content

How Police Detect Drunk Drivers

police officer standing in front of police car

In order for police officers to pull drivers over, they must have probable cause. To detect intoxicated drivers, they look for certain driving behaviors that tend to indicate that the driver is under the influence. Let’s discuss some common reasons why police stop drivers for suspected DUI.


Drunk drivers tend to swerve in their lane, or potentially into other lanes. This is because alcohol impairs one’s ability to focus and judge distance. Once they notice they are headed toward the other lane, they tend to overcorrect when they veer back into their own lane. This type of swerving is one of the most common ways that police officers detect drunk drivers on the road.


If a driver is under the influence, it is common that they will speed. Not only will they speed, but it’s also common to see them brake suddenly. This is because drunk drivers don’t have the ability to regulate their speed like they do when sober. These sudden accelerations and decelerations are dangerous for themselves and others on the road and give police probable cause to pull over the car.

Failure to Follow Street Signs

Impaired drivers may:

  • Run red lights
  • Roll through or ignore stop signs
  • Drive the wrong way down one-way streets

If a driver ignores road signs, the police will stop them to see what is going on.

After Being Pulled Over

Once the police officer has pulled over the driver who they believe may be intoxicated, they will continue to look for signs of impairment.

Once they are at the driver’s window, they will look for:

  • Slurred speech
  • Lack of coordination
  • Dazed look in eyes
  • The smell of alcohol or marijuana

If during this interaction the police find further reason to believe the driver is drunk, they may conduct a breath or field sobriety test.

If the driver refuses a breath test, they may have their license suspended. If the driver refuses a field sobriety test, however, there is no penalty. Tillotson & Martin, LLC always recommend saying no to field sobriety testing.

Virginia DUI Defense

Our team at Tillotson & Martin, LLC has the knowledge, experience, and drive to fight any DUI charges. If you believe your case is hopeless, we’re here to tell you that it’s not. Call us at (757) 568-7978 to get started with the criminal defense attorneys that wrote the book on Virginia DUI law.