21 Lack of Probable Cause Examples For A Police DUI Stop or Arrest

What Is Probable Cause?

In order for a law enforcement officer to stop your vehicle, they must articulate specific details that rise to the level of reasonable suspicion that a crime has been commited.  Reasonable suspicion only requires a minimal level of justification for the stop such as a traffic violation, equipment violation, or erratic driving.

The issue in these cases is did the officer act reasonably under the circumstances in stopping your vehicle and not on a mere whim, caprice or idle curiosity. Generalized suspicion is not enough1.

The law does allow a brief investigative traffic stop so long as the officer has a

particularized and objective basis for suspecting the person stopped of criminal activity2.

If the officer wishes to detain you for longer than necessary for a routine traffic stop because he/she suspects you are under the influence, the officer must have probable cause. This is a reasonable belief that you are impaired based on the office being able to articulate specific facts supporting a belief that you were driving under the influence of alcohol or drugs. This is a higher standard than reasonable suspicion. 

Probable cause also means that the officer must have a reasonable basis or belief for his suspicion which would cause a cautious person acting in good faith to believe that you are guilty of DUI. The officer must be able to point to known facts existing at the time of the determination that “would lead a man of ordinary care and prudence to believe and conscientiously entertain an honest and strong suspicion that the person is guilty of a crime.”3.

Motion To Dismiss

Absent probable cause, your case should be dismissed by the court before you get to trial in either a Penal Code § 1538.5 suppression motion or a Penal Code § 995 motion to dismiss hearing if a felony. 

In order for a law enforcement officer to stop your vehicle, they must articulate specific details that rise to the level of reasonable suspicion that a crime has been commited.  Reasonable suspicion only requires a minimal level of justification for the stop such as a traffic violation, equipment violation, or erratic driving. Generalized suspicion is not enough4.

We have put together 21 examples of a lack of probable cause for a DUI stop or arrest so that you can understand when an officer may have violated the law.

1) Police Not On The Scene

Police come to your residence several hours after a car accident, conducting an investigation into the driver.  They are operating on a statement from a witness that believes they saw your vehicle leave the scene of the collision.

When the officer arrives, he observes you at your home stumbling, slurring your speech, or exhibiting other signs and symptoms of being under the influence. If you make no statements or admissions to the officer, he can not arrest you based on this information alone.  There is insufficient probable cause without knowing when you began drinking and whether you were even involved in the collision, rather than another person that may have been driving your vehicle.

2) Not Clear Who Was Driving

You are found standing outside of your vehicle with other persons around the car and no one admits to driving. 

Even though the car is registered to you, there is no way for the officer to know who was driving and if that person was under the influence at that time. 

3) No Testing

You are arrested for DUI though you did not confess to drinking, no field sobriety tests were conducted, no PAS test was administered, and no other indicia of impairment is noted.

The officer has arrested you on the basis of a conclusion unsupported by any facts to which he could articulate as credible evidence of impairment. 

4) Racial Profiling

You were stopped based on your race such as for driving in an all-white neighborhood.  Race, religion, national origin, gender indentification, or creed cannot be the basis for stopping you. 

Although police will rarely, if ever, state that this is the sole reason why you were pulled over, your criminal defense attorney will have to demonstrate a substantial disparity in the race of persons who are stopped and detained or a disproportionate ratio of police stopping persons of color. Communications within the police department or from dispatchers, if recoverable, can point to racial bias in targeting certain groups of people, 

5) Vehicle Never Moved

You are arrested for DUI because the car engine was on but the officer never saw the vehicle move5.

Under California law, the officer must have seen your vehicle move, even if it was a few inches, or that you were about to engage the vehicle by turning it on. However, if the vehicle rolls forward or backward because the emergency brake is off and despite the engine being shut off, this constitutes driving. 

6) Arrested Based On Statements Alone

At a roadside sobriety stop, you are arrested for DUI after stating that you had two drinks but the police failed to either notice any other indicia or impairment or failed to follow proper procedures in setting up the roadblock.

Field sobriety roadblocks are legal in California so long as the stops are minimally intrusive and police follow certain criteria such as:

  • Supervising officers oversee the process and make all decisions on its operation
  • Basis for stops are neutral (random)–cannot stop you because of race or condition of your car
  • Checkpoing is reasonably and safely located
  • Roadblock was publicly advertised in advance
  • Roadblock was clearly marked as such
  • There was a way for motorists to turn and avoid the roadblock
  • Detentions are lasting too long

Although police do not require probable cause to ask you about drinking, a violation of the critieria for the roadblock can lead to suppression of any evidence used to incriminate you following a PC § 1538.5 motion. In this example, there was no probable cause to further detain you since the officer failed to detect any credible signs of impairment such as slurred speech or providing, incoherent or nonsensical responses to questions.

7) Found Asleep

You are found asleep in your car, the engine was running, and you demonstrated indicia of intoxication. 

Since you were not driving at the time, the officer did not see the vehicle move at all, a prosecutor cannot show any volitional movement of the car. So long as you did not attempt to engage the gears or to start the car, there is no probable cause to arrest you for DUI6. However, there may be circumstances where a prosecutor can show that there is no other way that the vehicle could have ended up where it did other than by your driving it there such as being in a remote area with no residences or businesses within miles, and the engine is running with you in the front seat. 

8) Merely Leaving A Bar

You were stopped because police saw you exit a bar after having observed the bar for several hours and see get into your vehicle and begin to drive. 

Merely because you left a bar after having been there for several hours does not justify a stop absent the officer having observed you violate a specific traffic law such as speeding, making an unsafe lane change, or failing to stop at a red traffic signal, or that you were weaving within or outside your lane of traffic or other unsafe driving conduct. 

9) Court Motions

At a Penal Code §1538.5 motion to suppress or Penal Code § 995 hearing if a felony, the officer provided no specifics on your driving conduct, performance on sobriety tests, or your demeanor and only testified generally that he stopped and arrested you based on these factors. 

10) Traffic Accident

You are arrested for DUI because you caused a traffic accident and no other indicia of impairment was noted by the officer. 

11) Late Night Driving

You were stopped because you were driving late at night or in the early morning hours.

12) Odor Of Alcohol

The officer arrests you for DUI based solely on his detecting an odor of alcohol and observing your bloodshot eyes. 

13) High Crime Area

The officer arrests you for DUI based solely on his detecting an odor of alcohol and observing your bloodshot eyes. 

These factors alone are insufficient to arrest you for DUI because these facts alone are not reasonably trustworthy information sufficient to warrant a prudent person to believe you had committed a crime ((Beck v. Ohio (1964) 379 U.S. 80, 91)). Also, drinking and driving is not illegal in California or in any other state so long as you are not driving impaired or your blood alcohol level is below 0.08%. 

14) Connected By Name Only

Officers are notified that a person named Steve was seen driving erratically and police know you as Steve and that you have a prior record of DUI and drug activity and stop you when you are seen simply driving.

15) Tinted Windows

However, the officer’s mistake of law must have been unreasonable because the law was clear and unambiguous in stating that tinted windows are legal. If the officer’s mistake was a reasonable one, though, then the stop was likely valid ((Heien v. North Carolina (2014) 135 S.Ct. 530)). It is unclear as to what is a reasonable mistake of law by a police officer.

An officer stops you based on the erroneous and unreasonable legal assumption that your tinted window is a violation of law7.

21 Examples

In order to detain and arrest someone for a DUI, a law enforcement officer must have probable cause. Attorney Diana Aizman explains probable cause as:

A reasonable belief  that a crime has been or is being committed.

The officer must be able to specifically articulate the reasons for this belief—a “hunch” is not enough.  There are three stages of probable cause required in the DUI process and each stage requires more proof and articulation than the last.

  • Reasonable Suspicion
  • Articulate Why The Officer Suspects A Crime
  • Establish Probable Cause For Arrest

1. Reasonable Suspicion

Unreasonable search and seizure is prohibited under the Fourth Amendment of the United States Constitution.8 This means that an officer must have reasonable suspicion that a crime is taking place before he is permitted to pull over your vehicle for a traffic stop.

Any traffic violation is enough for a police officer to pull you over.  Suspicion of driving under the influence is not necessary in order for the officer to stop you. The only exception to this rule is a sobriety checkpoint, which is an administrative procedure that has its own strict rules and guidelines9.

2. Articlute Why The Officer Suspects You

After you are pulled over, the law enforcement officer must have probable cause in order to begin a DUI investigation. Before an officer can start asking you questions about drinking he must be able to articulate why he suspects you of driving under the influence.  If the officer observes signs of intoxication, this is likely enough to establish probable cause for a DUI case10.  Some of these observations include:

  • Alcohol in the car, whether opened or unopened
  • The smell of alcohol on your breath or in the vehicle
  • Red, watery, or glassy eyes
  • Slurred speech
  • Disorientation, or fumbling

This is usually sufficient to establish enough probable cause for the officer to ask more in depth questions about driving under the influence.

3. Establish Probable Cause For An Arrest

Finally, probable cause is also required before the officer can make an arrest for a DUI.  For this, the officer must be able to establish exactly why he someone was arrested for a DUI.  This is the highest level of probable cause required because with it come severe consequences.  Some examples of probable cause include:

California has an implied consent law and after a DUI arrest, you have to submit to a

If at any point before, during, or after your arrest, the officer cannot establish to the court that there was probable cause to continue to the next phase of the investigation, your attorney should attempt to have the evidence suppressed in a 1538.5 Suppression Hearing11.  If your evidence is not suppressed, it is still a good opportunity for the lawyer to cross examine the officer and discover weaknesses in the prosecution’s case in order to get your charges dismissed or reduced later on in the proceedings.

Probable Cause FAQs

What exactly is a section 1538.5 Suppression Hearing?

When your attorney believes that the arresting officer did not have probable cause that you were driving under the influence, he or she can file a motion to suppress with the court.  This is a request to get all evidence that was obtained after there was no probable cause to be tossed out.  If the court grants this motion at the suppression hearing, your case may be dismissed for lack of evidence. If there is still other evidence against you that has not been suppressed, the prosecution may still move forward on your case but it will be weaker with the lack of evidence.

Do the police have to read me my Miranda rights when they arrest me?

Many people believe that it is a harmful mistake if a police officer does not read you your Miranda rights after you have been arrested.  This is a common misconception. An officer only has to read you your rights if two things happen: (1) you are lawfully placed under arrest, and (2) you are subjected to custodial interrogation. Custodial interrogation occurs when the officer asks you questions after your lawful arrest from which your answers could incriminate you and be used against you in your hearing.

What is the difference between probable cause and reasonable suspicion?

Probable cause is a stricter standard than reasonable suspicion.  However, it is common throughout court proceedings that the two phrases are used interchangeably.

Is my refusal to take a preliminary alcohol screening or to submit to the field sobriety test enough for probable cause?

Refusal of either a of these tests alone is not enough to for the officer to establish probable cause that you were driving under the influence.  However, it is important to remember that there may be other symptoms or signs that the officer articulates as his probable cause even without the field and breath tests.

Next Steps

If you have been arrested and would like to learn more about what attorneys charge.

If you want to understand why its important to have an attorney represent you.

If you are ready to discuss a pending case with an attorney contact the Aizman Law Firm at 818-351-9555 for a free confidential consultation.

Get Legal Help Now

Request A Free Consultation 818-351-9555 


  1. People v. Bower (1979) 24 Cal.3d 638, 644 []
  2. U.S. v. Cortez (1981) 449 U.S. 411, 417, 418; Terry v. Ohio (1968) 392 U.S. 1, 21 []
  3. People v. Price (1991) 1 Cal.4th 324, 410; Schmerber v. California (1966) 384 U.S. 757 []
  4. People v. Bower (1979) 24 Cal.3d 638, 644 []
  5. Mercer v. DMV (1991) 53 Cal.3d 753, endnote 4 []
  6. Music v. DMV (1990) 221 Cal. App.3d 841 []
  7. People v. Butler (1988) 202 Cal.App.3d 602, 606-607 []
  8. Constitution of the United States, Amendment Four []
  9. Ingersoll v. Palmer, 43 Cal.3d 1321 (1987 []
  10. Terry v. Ohio, 392 U.S. 1 (1968 []
  11. Cal. Penal Code section 1538.5(a)(1)(A []

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