Under the Fourth Amendment of the U.S. Constitution, a person cannot be searched or seized without law enforcement officials first having probable cause to do so. What this means is that before an officer can search someone's property, stop someone, or arrest someone, they must be able to point to concrete evidence for doing so. Their actions cannot be based on curiosity or a hunch. This is true in any criminal matter, including DUI stops and arrests.

What Is Probable Cause for a DUI Stop?

Generally, a DUI matter begins with a traffic stop, and that stop must be based on probable cause. Meaning an officer must have observed some type of behavior that violated a law.

However, the driver's behavior does not have to suggest that they are under the influence of drugs and/or alcohol. For instance, an officer could have probable cause to pull someone over if they are driving with expired tags or without a working headlight. The stop could have also occurred because the driver was swerving between lanes or ran a red light. In either case, the officer has something they can point to for justifying the stop. Therefore, they have probable cause.

The only time the police don't need probable cause in a DUI matter is when the stop is part of a checkpoint. Of course, law enforcement officials must follow proper processes to ensure that these types of stops are lawful.

What Is Reasonable Suspicion for a DUI Investigation?

Although often used interchangeably with probable cause, reasonable suspicion is a different legal theory. However, similar to probable cause, an officer must have reasonable suspicion before they begin a DUI investigation.

After the officer stops the driver, something in their behavior must justify further investigation into a possible DUI matter. For instance, if the officer asks whether or not the person has been drinking and they answer "yes," the officer may proceed with the investigation.

What Is Probable Cause for a DUI Arrest?

Before an officer can arrest someone on suspicion of driving under the influence, they must again have probable cause to do so. The results from their DUI investigation may provide the concrete evidence they need to justify taking a driver into custody.

Officers may look at various factors to establish probable cause for a DUI arrest, including but not limited to the driver:

  • Failing field sobriety tests
  • Having a high BAC on a preliminary breath test
  • Exhibiting signs of intoxication, such as slurring their words or smelling of alcohol

What Happens If Probable Cause Wasn't Established?

If an officer did not have a justifiable reason to pull a person over or arrest them on suspicion of drinking and driving, the driver could file a motion to suppress evidence. Anything obtained during an unlawful search or seizure is not admissible in court, and if the motion is granted, the state's case may be weakened, and the charges may be dismissed.

At Koenig Law Office, we have an in-depth understanding of California's DUI laws and know what defenses can be raised in these types of cases. To discuss your circumstances and legal options, call us at (661) 793-7222 or contact us online today. We are proud to help residents of Bakersfield and the surrounding areas.