Probable Cause and California DUI Stops, Detentions, and Arrests

In order to arrest you for a California DUI under either Vehicle Code 23152a VC driving under the influence or Vehicle Code 23152b VC driving with a BAC of 0.08% or greater, an officer must have probable cause to do so.  "Probable cause" means a reasonable belief that criminal activity (in this case, drunk driving) is or was taking place.

In order to stop or detain you for a California DUI, an officer must have a reasonable suspicion that criminal activity is or was taking place.  Because these two standards are so similar...and are often used interchangeably to challenge the validity of a

  • DUI stop,
  • DUI investigation, and/or
  • DUI arrest...

we are going to discuss both standards under the umbrella of "probable cause".  This is because the way to dispute the legality of any of these California DUI stages is through what's known as a PC 1538.5 probable cause hearing (discussed below).

If your California DUI defense attorney can prove that probable cause didn't exist during any one of these stages, your DUI charges could be reduced or even dismissed.  This remedy is based on a legal principle known as the "fruit of the poisonous tree".  It means that any evidence obtained as a result of an illegal procedure is subject to suppression.  When a judge "suppresses" evidence, it means he/she will not permit it to be used against you.

Let's now turn to these three levels of a DUI investigation to see exactly what level of suspicion is required for each.

Probable cause is necessary before the police can pull over a motorist for DUI

The Fourth Amendment to the United States Constitution prohibits unreasonable searches and seizures.1 This means that an officer can't simply stop your car for no reason.  In fact, in the landmark case Terry v. Ohio, the United States Supreme Court held that an officer must provide "specific articulable facts" that a crime is or was taking place before he/she can initiate a traffic stop.2

This doesn't mean that the officer must believe that the driver is DUI.  Any traffic infraction or violation will suffice.  If, for example, an officer notices that a driver's brake light is out, the officer would be entitled to stop that car.  As long as the officer is able to articulate some reason for initiating a traffic stop, probable cause is usually satisfied at this level.

The exception to this rule (as it pertains to California DUI laws) lies in California DUI sobriety checkpoints.  California DUI sobriety checkpoints are considered "administrative procedures" instead of criminal investigations.3 This distinction gets them around the probable cause requirement that is otherwise necessary to stop a car.

Probable cause is necessary before the police can begin a California DUI investigation

If, after stopping your car, the police believe you may be drunk driving, they will likely detain you for a DUI investigation.  In order to detain you, an officer needs a reasonable suspicion or probable cause to do so.  This means that before the police can investigate you for driving under the influence, they must have a reasonable suspicion that you are, in fact, DUI.

With each phase of the DUI...that is, the stop, the detention, and the arrest...comes a higher requirement for probable cause.  So while it may be fairly easy for an officer to satisfy the probable cause requirement to stop your car, the level of proof necessary to detain you becomes increasingly more difficult.

This means that before the police can detain you to conduct a DUI investigation...that is, ask you

  • multiple questions about what, where, and when you were drinking,
  • to perform field sobriety tests, and/or
  • to submit to a preliminary alcohol screening device (a mini handheld breath test)...

there must be some specific articulable facts that would lead a reasonable officer to believe that you are, in fact, DUI.

Many officers routinely ask drivers whom they stop at night if they've been drinking.  Even if you've only consumed a marginal amount of alcohol, a yes answer may give rise to probable cause and a subsequent California DUI investigation.

Regardless of whether you answer this question...or whether it is even asked...if the officer

  • observes an open container of alcohol in the car,
  • smells the odor of an alcoholic beverage on your breath,
  • observes red/watery eyes or a flushed face,
  • or any of the other common signs/symptoms of impairment,
  • and can articulate these facts,

then it is likely that he/she will satisfy the probable cause requirement for a DUI detention.  However, if none of these factors was immediately or readily observable, any subsequent California DUI field sobriety tests (FSTs) and/or California DUI chemical blood or breath test results may be excluded from evidence.

Probable cause is necessary before the police can make a DUI arrest

Finally, an officer must have probable cause to make a DUI arrest.  This means that the officer must be able to articulate exactly why he/she believes you were DUI...a hunch or mere suspicion will not suffice.  This is not negotiable, because when you are arrested, you are taken into police custody and no longer permitted to leave.  In fact, an actual arrest can trigger additional constitutional protections, such as Miranda rights.

Miranda rights must be read to a DUI suspect if (1) he/she has been arrested, and (2) is the subject of a custodial interrogation.4

The point here is that because an arrest is such an absolute invasion of your personal privacy, it requires the highest level of personal protection available.  This is why an arresting officer must be able to articulate the exact facts that led him/her to believe you were DUI.

Although these facts won't necessarily be related from the officer directly to you, they should be contained in the report.  More importantly, the officer must be able to convince the court that his/her actions were lawful and reasonable.

This means that the officer must be able to explain the reasons why he/she believed that, for example, your California DUI field sobriety test performance wasn't satisfactory.  Blanket conclusions aren't enough...the officer must provide specific articulable facts to support his/her claims.

1538.5 Suppression Hearing

If your California DUI defense attorney suspects that the officer lacked probable cause during any of the above stages, he/she will likely move to suppress any illegally obtained evidence.  This is one of the most popular motions that attorneys make when fighting California DUI charges.

Commonly referred to as a probable cause hearing or a PC 1538.5 hearing5, this suppression hearing challenges whether the police had probable cause.  During this motion, your DUI defense lawyer will ask the court to suppress the requested evidence against you because it was obtained in violation of your Constitutional right to remain free from unreasonable searches and seizures.

What evidence your attorney will ask the court to suppress will depend on when he/she believes the officer lacked probable cause.  Your attorney will ask that all evidence obtained as a result of the alleged illegal stop, detention, or arrest be excluded from your case.

If, for example, you and your California DUI defense lawyer believe that the officer didn't have probable cause to

  • pull you over (because you didn't commit a violation or infraction),
  • detain you (because you didn't display any signs/symptoms of intoxication), or
  • arrest you (you only had one beer and knew that you were not impaired),

he/she may challenge the officer's entire account of your DUI investigation.

It is important to note that 1538.5 motion to suppress hearings typically aren't granted.  Even so, as prominent Oakland DUI defense attorney Jim Hammer explains6, "Many California DUI defense lawyers will still run this motion for strategical reasons.  This is a pre-trial opportunity to cross-examine the officer and to discover any weaknesses in the prosecution's case...weaknesses that may result in reduced or even dismissed DUI charges."

Call us for help.

If you or loved one is charged with a DUI and you are looking to hire an attorney for representation, we invite you to contact us at Shouse Law Group. We can provide a free consultation in office or by phone. We have local offices in Los Angeles, the San Fernando Valley, Pasadena, Long Beach, Orange County, Ventura, San Bernardino, Rancho Cucamonga, Riverside, San Diego, Sacramento, Oakland, San Francisco, San Jose and throughout California.

You may also find helpful information in our related articles on Vehicle Code 23152a VC Driving Under the Influence, Vehicle Code 23152b VC Driving with a BAC of 0.08% or Greater, California DUI Laws, and Fighting California DUI Charges.

Legal References:

1Terry v. Ohio, (1968) 392 U.S. 1, 20 ("But we deal here with an entire rubric of police conduct-necessarily swift action predicated upon the on-the-spot observations of the officer on the beat-which historically has not been, and as a practical matter could not be, subjected to the warrant procedure. Instead, the conduct involved in this case must be tested by the Fourth Amendment's general proscription against unreasonable searches and seizures.")

2See same at 21.  ("And in justifying the particular intrusion the police officer must be able to point to specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant that intrusion [with respect to a California DUI investigation].")

3Ingersoll v. Palmer (1987) 43 Cal.3d 1321, 1327.  ("If the primary purpose of the stop here were to detect crime or gather evidence of crime, we would agree with the contention that an individualized suspicion of wrongdoing is required. But, as we shall explain, the primary purpose of the stop here was not to discover evidence of crime or to make arrests of drunk drivers but to promote public safety by deterring intoxicated persons from driving on the public streets and highways. We therefore conclude the propriety of the sobriety checkpoint stops involved here is to be determined not by the standard pertinent to traditional criminal investigative stops, but rather by the standard applicable to investigative detentions and inspections conducted as part of a regulatory scheme in furtherance of an administrative purpose.")

4Miranda v. Arizona, (1966) 384 U.S. 436, 444. ("...the prosecution may not use statements, whether exculpatory or inculpatory, stemming from custodial interrogation of the defendant unless it demonstrates the use of procedural safeguards effective to secure the privilege against self-incrimination. By custodial interrogation, we mean questioning initiated by law enforcement officers after a person has been taken into custody or otherwise deprived of his freedom of action in any significant way.")  In short, these Miranda rights apply to California DUI investigations when (1) the suspect has been arrested, and (2) is the subject of a custodial interrogation.

5California Penal Code 1538.5 -- Motion to return property or suppress evidence.  ("(a)(1) A defendant may move for the return of property or to suppress as evidence any tangible or intangible thing obtained as a result of a search or seizure on either of the following grounds: (A) The search or seizure without a warrant was unreasonable [as is the case with California DUI arrests].")

6Oakland DUI defense attorney Jim Hammer uses his former inside experience as a San Francisco District Attorney to defend clients accused of DUI in the Bay area, including San Francisco, Oakland, Berkeley, Marin County, and San Jose.  Please feel free to contact us with any questions regarding Mr. Hammer's outstanding credentials.

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