8 Police Failures At DUI Checkpoints That Can Be Challenged

Police officers or departments can make mistakes when instituting a DUI checkpoint which can impact the outcome of the court case.  Should the police fail to follow certain procedures, a motion to exclude or suppress incriminating evidence or to dismiss the charges against you can be filed. Below is a list of eight mistakes we’ve seen police officers make at DUI checkpoints as well as case law explained that determined the parameters of DUI checkpoint law.

Case of Ingersoll v. Palmer

In criminal law, a person may not be detained or stopped while driving a motor vehicle without probable cause. In other words, a police officer must have a reasonable suspicion that would that a crime has occurred or is about to occur, and that when stopping the person “that it may be objectively reasonable for him to do so.”1.

Under the 4th Amendment to the US Constitution, it is a firmly held and much cherished right that we be free from unreasonable searches and seizures and that no one be searched or their property seized without a warrant. For most of our history, we have protested whenever our right to privacy and to be free from governmental intrusion is violated.

Exceptions To Fourth Amendment

However, the court has carved out exceptions to the 4th Amendment, especially to the warrant requirement and when we can be stopped and searched. In Ingersoll v. Palmer (1987) 43 Cal.3d 1321, the court made such an exception when we are in our automobiles by allowing law enforcement to stop motorists without probable cause for the limited purpose of making a quick determination if they are under the influence. To get around 4th Amendment objections, the court rationalized its decision by characterizing such stops or checkpoints as a method of deterring persons from driving while impaired and that such limited intrusions are an administrative inspection rather than an investigation of possible wrongdoing.

Public Interest vs. Individual Right

In allowing such limited intrusions, the court had to weigh the public interest served by the stop and detention and the degree of intrusiveness to an individual’s right of liberty. It reasoned that the public interest does supersede or outweigh an individual’s right to be free from unwarranted stops so long as there are adequate safeguards in place that does away with randomness and makes the stop as unobtrusive as possible. 

Court Compared DUI Checkpoints To Airport Screenings

The court compared DUI checkpoint stops to the airport pre-departure screening of passengers that courts have upheld as “…part of a general regulatory scheme in furtherance of an administrative purpose, rather than as part of a criminal investigation to secure evidence of a crime…”2. Airport screenings like DUI checkpoints are not for the purpose of seizing contraband or to preserve evidence for criminal prosecution. Rather, these are designed to prevent persons from bringing on-board dangerous weapons or other items and to deter hijackers.

Requiring a warrant for every search of a bag is fundamentally unsuitable or impractical due to the high volume of passengers and the time and procedure involved so long as there was a neutral application of the screening process and the intrusiveness to the passengers was minimized3

In the context of DUI Checkpoints, the court extended the rationale behind screening passengers before boarding to that of motorists who could pose significant dangers to other motorists and pedestrians by articulating a number of guidelines for law enforcement to follow so that DUI Checkpoints can survive constitutional scrutiny. 

8 Factors Used in Determining the Legality of a DUI Checkpoint

1. A supervising officer must make all constitutional decisions

Before the checkpoint is established, an administrative officer and not a field officer or one on the scene must make operational decisions about how the checkpoint is to be conducted. This is to prevent unconstitutional profiling that would have certain persons singled out on the basis of race or national origin or other particular traits for detaining and questioning and to reduce the potential for arbitrary and capricious enforcement4.

Such decisions include the date for the checkpoint, location of the site, and how they are to select vehicles to be briefly detained.

2. Motorists must be stopped on a neutral, impartial basis

A decision as to which vehicles are to be stopped is to be made by the administrative officer before the checkpoint is established on-site. It may not be at the discretion of any field officer. For instance, the officers may be directed to stop 5 consecutive vehicles, let 2 proceed, and then stop the next 5 cars. A guideline cannot be to stop all Cadillacs or persons who appear to be of a certain age or ethnicity, or males only. 

3. The location must be reasonable

The checkpoint must be in an area where there have been a high incidence of DUI arrests or alcohol-related accidents so that the checkpoint can be more effective in stopping impaired drivers. 

4. There must be safety precautions

Another requirement is to implement safety precautions so that motorists can safely stop and navigate to and through the checkpoint in an area that can safely accommodate the checkpoint and the flow of traffic. For instance, there should be adequate lighting and the checkpoint set up at a time and place where the volume of cars passing through is manageable. But if traffic begins to back up, they are to have an alternate plan already in place to deal with congestion by altering certain practices. This can include stopping every 4th vehicle rather than 5 consecutively. Further, motorists should be given adequate warning or notice that a checkpoint is ahead or that it is clearly visible so as to minimize panic among approaching  motorists who may engage in unsafe maneuvers to avoid being stopped. 

5. The time and duration must be reasonable

There is no time limit on how long a checkpoint can be operational. It is permissible for one to last an entire weekend so long as the burden on motorists is not substantial. 

Those supervisors or administrators tasked with setting up the checkpoint should ensure that the time of day when the checkpoint will be in operation and its duration are reasonable so as to cause only minimal inconvenience to motorists. For instance, a checkpoint on a busy stretch of roadway during rush hour is probably unreasonable.

6. There must be signage for the checkpoint

Motorists must be alerted to the presence of the checkpoint by signs posted in advance of the checkpoint. Officers can also have flashing lights on several vehicles along with a number of marked police cars leading to the stopping point. This gives drivers time to see that they are approaching an official area where they may be asked to stop and minimizes a feeling of fear that could lead to motorists suddenly and unsafely attempting to avoid the checkpoint. 

7. Drivers should be detained for the shortest time possible

An essential component of a DUI Checkpoint is to detain drivers for the shortest time possible so as to lessen the intrusive nature of the operation. Officers are trained to quickly recognize signs of impairment that can include:

  • Slurred speech
  • Odor of alcohol
  • Dazed appearance
  • Glassy or bloodshot eyes
  • Incoherent responses or speech

Generally, an officer will ask a few questions of the motorist and observe his/her appearance and demeanor within a minute or so of the stop. If no signs of impairment or intoxication are immediately noted, the motorist should be allowed to leave. If these or other signs of possible impairment are observed, then the officer may further detain the motorist so long as the officer reasonably suspects impairment. 

8. The checkpoint must be advertised in advance

Any DUI Checkpoint must be advertised to the public in advance. Notice is generally reasonable if given one week in advance. The purpose of the notice is to deter drivers from drinking and driving in these areas, which are generally locations where high incidences of DUI arrests or alcohol-related accidents have occurred, and to put motorists on notice that their liberty or privacy could be violated if only for a minimal time. 

Notice of the checkpoint including the date and time can be found on law enforcement websites, television and radio news stations, and in your local newspaper or town website. 

Challenges to a DUI Checkpoint

If you are stopped at a DUI Checkpoint, asked or told to be detained for a longer time so that a further investigation of your possible impairment can be undertaken, asked to take a breathalyzer test, and then arrested, are there defenses or challenges to the checkpoint itself?

The above 8 guidelines that every California police department must follow is to deter drunk or drugged driving but to do so in a manner that only inconveniences drivers for the shortest time possible. The state’s interest is in protecting the public while also adhering to constitutional principles regarding privacy and your right to be free from unreasonable governmental intrusion. After all, you are being stopped without probable cause.

As noted above, this is considered more of a regulatory measure than one designed to nab impaired drivers, though the real purpose of the checkpoint is obvious. However, not all of the 8 guidelines are considered equal; indeed, some are more equal than others. For example, there is no standard for where to post warning signs about the approaching checkpoint or that a certain number of marked police vehicles be present with lights flashing. So long as it appears reasonable, then a court will likely not invalidate your arrest on this basis alone.

Credible Challenge

A credible challenge may be mounted if there is evidence that you were stopped at random and not pursuant to a pre-arranged or neutral method outlined by a supervisor regarding which vehicles will be stopped. If the method becomes too burdensome, there must also be in place an alternate routine. Should your DUI defense attorney demonstrate that officers in the field decided on their own to use their own method of stopping cars that did not comply with the pre-determined one, then you may have a successful challenge. 

Other issues that can be raised in a DUI Checkpoint prosecution can include:

  • What were the identities of the persons arrested for DUI? Were all or substantially all defendants of a certain race, ethnicity, age or appearance?
  • How long was each driver detained?
  • How much advance notice was given to the public about the checkpoint?
  • Were motorists allowed to safely avoid the checkpoint or were they detained or blocked from doing so even if they were doing so safely and legally?
  • Did the checkpoint have sufficient signs of its official nature?
  • Did the officer have a reasonable suspicion to detain the defendant?
  • Was there probable cause to request the defendant to perform field sobriety tests and to take a chemical test of his or her blood or breath? (Generally, there is a vehicle or van where the breath test can be administered)
  • How were the checkpoint procedures established—this may entail a review of all documents and communications regarding its operation
  • Where was the checkpoint established and was it in a reasonable location?

Challenging a DUI Checkpoint stop can be complex and requires that your defense attorney have the knowledge and experience in mounting a successful defense based on the lack of adequate safeguards in how the operation was set up and the methods used to detain and arrest those suspected of DUI.

Motorists Obligations

As a motorist, you are under no legal obligation to answer any questions posed to you by a police officer. You do have to produce your driver’s license, registration and probably insurance card, however, and you can be ticketed for refusing to comply. You are also under no obligation to perform any roadside sobriety tests including walking heel to toe, one leg stand, or other balance tests, or blowing into a PAS or preliminary alcohol screening device. 

However, if the officer requests that you undergo chemical testing such as being administered the breathalyzer or a blood test, then your refusal can lead to civil and criminal consequences, unless your attorney can show that the officer lacked probable cause.

DUI Checkpoint FAQs

Are DUI Checkpoints illegal in California?

No. Under state law, police departments are permitted to set up roadblocks where police officers may detain motorists for a short time to determine if they are driving while impaired. However, there are numerous guidelines that police departments are required to follow or a defendant arrested at a checkpoint may successfully challenge his or her arrest.

For instance, there must be a neutral, pre-determined process by which vehicles are selected to be stopped; the checkpoint must be adequately identified; there must be advance notice to the public of the roadblock; and all detentions must be as short as possible. Talk to a DUI defense attorney if you were arrested at a DUI Checkpoint in California.

It is illegal to turn around at a DUI Checkpoint?

No, you may legally turn around to avoid a checkpoint so long as you do so safely and without violating any traffic laws. For example, if you make an illegal or unsafe U-turn, you will likely be stopped and cited. If the officer who stops you has a reasonable suspicion that you are driving impaired, then the officer can further investigate.

If you do turn around at a checkpoint and do so safely and legally but are stopped nonetheless, your defense attorney can assert that the officer had no probable cause to stop and detain you. Further, if officers are detaining all motorists who attempt to avoid a DUI Checkpoint, this can be further evidence of an unlawful seizure by police. 

Can a driver refuse to cooperate?

You may politely refuse to answer any questions by police such as whether you have been drinking, whether you were at a bar or restaurant, or any other question. You can also refuse to undergo any field or roadside sobriety tests that you are asked to perform. However, you are required to produce your driver’s license and registration, if not your insurance information as well. Further, under California’s implied consent law, you are legally obligated to undergo a chemical test of your breath or blood so long as the officer had probable cause to arrest you and to make the request, and give you the required admonitions about the test. If you refuse chemical testing and probable cause is found, you face significant civil penalties such as loss of your driver’s license for at least one year and certain criminal consequences. 

What happens if you do not have a license at the checkpoint?

If you merely forgot your license and it is valid, you can give the officer your license number if you can recall it and after checking it, the officer may allow you to proceed provided you show no signs of impairment. However, you can be ticketed for an infraction under CVC Section 12591 for not having it with you but you will be required to produce it to a court clerk or in traffic court and have the matter dismissed. If you do not have a valid driver’s license, you can be arrested pursuant to California vehicle code section 12500 and face a fine of up to $1,000 and impoundment of your vehicle unless you can have a licensed individual arrive to drive the vehicle away while the checkpoint is in operation. 

Can your car be impounded if you do not have a license at a checkpoint?

Yes, but only if you do not possess a valid driver’s license or you were driving on a suspended license. However, you can contact a validly licensed individual to retrieve the vehicle from the checkpoint to avoid impoundment. If it is impounded, it can be kept for 30-days and costs can exceed $1,500. If the fee is not paid, it is subject to being sold at auction. 

Do you have to stop at a DUI Checkpoint in California?

Yes, you do have to stop since a brief detention at these checkpoints is not considered a “seizure” under the U.S. Constitution but an administrative inspection. 

Next Steps If You Need Help

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

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

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

Request A Free Consultation 818-351-9555 


  1. People v. Superior Court (1970) 3 Cal.3d 807, at p. 827 []
  2. People v. Hyde (1974) 12 Cal. 3d 158, 165-166 []
  3. People v. Hyde, supra, 12 Cal. 3d 158, 166 []
  4. Ingersoll v. Palmer, supra, 43 Cal.3d 1342 []

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