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Probable Cause to Stop a Vehicle in Alameda and Contra Costa County

To be arrested for a crime in California, the police officer must have probable cause to believe you have committed a crime. Before the police can pull a driver over, the officer has to have reasonable suspicion to stop the vehicle in the first place. If the police stop a car without cause, the defendant's defense attorney may be able to suppress evidence of a crime.

Search and Seizure:

The Fourth Amendment to the United States Constitution protects persons from unreasonable search and seizure. For drivers who are pulled over and arrested, the Fourth Amendment generally protects them from being stopped by the police without sufficient probable cause to suspect a person is involved in a crime. This includes individuals suspected of driving under the influence of alcohol or drugs.

What is “probable cause”?

Probable cause is the requirement that police have sufficient facts and circumstances before them that would lead a reasonable person to believe a person has committed a crime, in order to make an arrest.

What is “reasonable suspicion”?

Reasonable suspicion means the facts that would lead a reasonable person to believe that a crime has or will take place, and that further investigation is warranted. This requires more than a “hunch” or gut feeling that someone is involved in a crime. An officer generally has to base their reasonable suspicion on facts or circumstances of criminal activity based on the police officer's training and experience.

Probable Cause or Reasonable Suspicion to Stop the Car

When the police pull over a car, they cannot just do so based on a hunch or generalized suspicion. To temporarily stop the car requires that the police have a reasonable suspicion that the driver has violated a traffic law, is driving under the influence, or has committed a criminal offense.

Traffic Violations to Stop the Car

In order to pull over a vehicle, the police have to have a reasonable suspicion that the driver has committed a traffic violation, the vehicle is operating in violation of state regulations, or the driver may be involved in a crime.

For a drunk driving arrest, an officer could have the specific and articulable facts that a driver is under the influence sufficient to constitute reasonable suspicion of a DUI, such as suspicious driving patterns. For example, if a car is weaving between lanes, straddling lanes, hits the curb, or driving well below the speed limit, this may be the reasonable suspicion of an intoxicated driver. The officer may be able to temporarily stop the car and further investigate the driver's level of sobriety.

Alternatively, if the police pull you over and arrest you for a DUI, they do not necessarily have to have suspected a DUI at the time of pulling you over, as long as they had a legitimate reason to initially stop the car. This often occurs when the police witness the driver committing a minor traffic infraction.

For example, if a car has a taillight out, the vehicle registration is out of date, or the driver is talking on the cell phone, then the officer would have the justification required to initially stop the vehicle. After stopping the car for the traffic offense, they may suspect the driver is under the influence and arrest the driver for a DUI.

Exceptions to Stopping the Car for Reasonable Suspicion

There are exceptions to requiring reasonable suspicion to stop a car. One exception involves stopping a vehicle without reasonable suspicion during a sobriety checkpoint. A sobriety checkpoint has been deemed by the courts as an “administrative procedure” rather than a criminal police stop. However, even a sobriety checkpoint has specific rules and guidelines to follow.

Investigating a DUI

After being pulled over, if the police continue detaining you in order to investigate whether the driver is under the influence, they have to have specific and articulable facts and observations to justify the DUI investigation. This can include:

  • smelling alcohol in the car or on the driver's breath;
  • blood-shot eyes;
  • smelling marijuana in the car or on the driver;
  • slurred speech;
  • alcohol or drugs visible in the car; or
  • the driver admitting to drinking alcohol.

Probable Cause for a DUI Arrest

In order for a police officer to arrest someone for a DUI, they have to have probable cause that the driver was under the influence of alcohol or drugs. This can come from field breath tests, field sobriety tests, or even the driver admitting they have been drinking alcohol or smoking pot.

What happens if there was no probable cause or reasonable suspicion to stop the car?

Where the officer did not observe some infraction, or traffic violation to pull over the car, then they had to have had reasonable suspicion to stop the car. If the officer did not have reasonable suspicion to justify the detention, then evidence obtained as a result of the unlawful stop may be suppressed.

Additionally, in order to be placed under arrest for a DUI, the officer must have probable cause that the driver was under the influence of alcohol or drugs. Without probable cause, the evidence obtained after the arrest would be suppressed.

Suppressing Evidence of Without Probable Cause

To have evidence suppressed, a defense attorney can file a motion to suppress. During a suppression hearing, the attorney will present law and facts to show that the police did not have probable cause to stop the vehicle. The prosecutor will also argue in opposition to the motion to suppress. If the court finds the police did not have probable cause to stop the vehicle, the judge may grant the motion to suppress evidence. This could even result in the entire case being dismissed.

East Bay Criminal Defense Attorney

Lynn Gorelick has more than 30 years of criminal defense experience defending her clients facing misdemeanor and felony criminal charges in the East Bay. She understands how to approach the individual facts of each case for the greatest chance of success, keeping her clients out of jail and keeping a clean record. Whether you are arrested in Oakland, Richmond or anywhere else in Contra Costa County or Alameda County, contact Lynn Gorelick.

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We offer a free initial consultation to people accused of DUI and criminal offenses in the Bay Area. Call us at 510-785-1444 to schedule yours.

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