Monday – Friday 8am-6pm

Current DMV News & Articles

Authored By DMV Defense Experts

Probable Cause at an Administrative Per Se/DUI Hearing?

You Only Have 10 CALENDAR Days To Contact The DMV To Initiate Your Defense. Contact Our Team Immediately To Initiate Your Defense.

When a driver in California has been arrested or detained for driving a motor vehicle with a blood/alcohol concentration which is “at or above” the legal limit, the Administrative Per Se Law mandates that the DMV immediately suspend or revoke that person’s privilege to drive in California. If the accused driver seeks to defeat the intended suspension of their driving privilege, they must schedule, conduct, and win an administrative hearing called an Administrative Per Se Hearing. Also known as an APS Hearing, the driver has three primary issues to attack:

  • Did the law enforcement officer have probable cause to contact the driver?
  • Did the law enforcement officer have probable cause to lawfully arrest or detain the driver?
  • Was the driver’s blood/alcohol centration at or above the legal limit at the time of driving.


Probable Cause is the standard by which an officer or agent of the law has the grounds to contact a citizen, make a traffic stop, make an arrest, conduct a search or obtain warrants. The term comes from the Fourth Amendment to the United States Constitution:

“The right of the people to be secure in their persons, houses, papers and effects, against unreasonable searches and seizures, shall not be violated and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”

The Oxford Companion to American Law defines Probable Cause as:

“Information sufficient to warrant a prudent and cautious person to believe that an individual has committed a crime or that sufficient evidence exists to warrant further investigation.”

Black’s Law Dictionary defines Probable Cause as:

A set of probabilities grounded in the factual and practical considerations which govern the decisions of reasonable and prudent persons and is more than mere suspicion but less than the quantum of evidence required for conviction.”

 At a DMV Administrative Per Se (APS) Hearing, the question of Probable Cause most often arises as to whether or not a law enforcement officer had a lawful reason to contact, meet with, detain, or question a driver in the first place.

Although there are some exceptions to the rule, Probable Cause is normally an important and powerful tool in fighting to win an APS Hearing.

Why is Probable Cause Important at an Administrative Per Se/DUI Hearing?

With few exceptions, the original contact between a law enforcement officer and the driver of a motor vehicle requires that the officer have probable cause to make the initial contact. Whether it is during a traffic stop or when a police officer approaches a parked vehicle, the officer must be able to articulate that he had probable cause to believe that a person has committed a crime or is about to commit a crime.

Probable Cause for the initial contact is enormously important in our system of justice because everything that follows, such as an investigation, arrest, and collection of chemical test results all flow from the original contact. There is a doctrine in the law known as “The Fruit of the Poisonous Tree.

“Evidence which is spawned by or directly derived from an illegal search or illegal interrogation is generally inadmissible against the defendant because of its original taint.”

This is important at an APS Hearing because if it can be demonstrated that a law enforcement officer’s original contact or detention of a driver was void of probable cause, all evidence which is derived from that tainted contact is potentially inadmissible.


How Do the Police Establish Probable Cause at an Administrative Per Se/DUI Hearing?

In DUI arrests, probable cause usually centers on the circumstances which causes a police officer to make initial contact with a driver, which then results in the driver’s arrest for DUI. In most DUI cases, an arrest occurs after a police officer witnesses some violation of the California Vehicle Code and conducts an enforcement stop to cite or warn the driver. An officer may witness violations such as speeding, failing to stop for a red light, or a stop sign violation. These issues are not necessarily evidence of impaired driving but certainly are probable cause for a police officer to affect an enforcement stop. Failing to turn on a vehicle’s headlights at night or having mechanical problems with a car also provides a police officer a reason to make a traffic stop.

In their overzealous focus to remove drunk drivers from the road, however, police officers will often resort to stopping motorists at will and then “invent” their probable cause later. This classically occurs during the early morning hours when the percentage of impaired drivers is thought to be higher. Police officers will “troll” through areas where restaurants and bars are located and will stop drivers simply because they leave a location where alcohol is served. In the law enforcement community, this is referred to as “cherry picking.” The driver may not have committed a single violation of the law; the driver may not have demonstrated a single “clue” that he/she is impaired but they are stopped nonetheless. The officer makes his initial contact with the driver and, if the driver is determined to be sober, the officer may simply say he stopped the driver because his car met the description of one the officer was searching for. On the other hand, if the driver is thought to be impaired, the officer will “invent” his probable cause for the stop by alleging that the driver had been “weaving.” This is a completely subjective evaluation of a person’s driving pattern but is prolific in police reports.

The California Vehicle Code empowers police officers to conduct enforcement stops on vehicles for a wide range of violations that are not necessarily thought to establish the symptoms of impaired driving but, nonetheless, can lead to a DUI arrest. Faulty or non-functioning lighting equipment, an obstructed windshield (necklace hanging from rear-view mirror), a cracked windshield, loud radio, tinted windows, expired vehicle registration, vehicles equipped with substandard mud flaps, bald tires or loud exhaust, are all lawful reasons for a law enforcement officer to stop a driver as a pretext to determine if they have been drinking.

All “moving violations” also expose a driver to being stopped when law enforcement officers are searching for impaired drivers. Some of the most common moving violations that lead to DUI arrests are:

  • Speeding
  • Driving too Slowly
  • Weaving
  • Failure to Properly Stop for Stop Signs
  • Failure to Stop at Traffic Lights
  • Pausing Too Long at a Stop
  • Driving at Night without Headlights
  • Illegal U-Turn
  • Failure to Use Turn Signal

Once a law enforcement officer sees any valid violation of the Vehicle Code, he has established probable cause for the initial contact of a driver. If the officer contacts the driver and then detects any symptoms of alcohol use, a DUI investigation will begin. At that point, the original reason for the stop becomes secondary to the DUI investigation but is used as the probable cause to justify the initial contact.

Call Us. We Can Help You Fight the Probable Cause in Your Case.

 If a creative police office is intent on making DUI arrests, he is armed with a vast array of reasons to stop a motorist and, when he can’t find something listed above, he can simply say that the driver was “weaving.”

Attacking the Probable Cause for a traffic stop is a core element to defending drivers at any Administrative Per Se Hearing. A complete investigation of the events leading up to the stop or initial contact with the client is crucial. Because police officers are specifically trained to establish probable cause and because they are trained in the methods to properly document their actions in a police report; attacking probable cause can be difficult. Review of independent witnesses, dash-cam video, or other sources of video may give the driver’s representative just the ammunition necessary to defeat the initial stop or contact. If the Probable Cause for the stop if faulty, this is cause to win a hearing.

The DMV Defense Experts at California Drivers Advocates have been attacking probable cause at APS Hearings for years. Knowing how to discover evidence that probable cause is weak, and knowing how to properly introduce that evidence in a format that the DMV can’t ignore; is why we are so successful at winning APS Hearings. A successful attack on probable cause can be difficult, but done correctly can make the difference between winning and losing.  Call CDA today and let us go to work saving your driver license.

If the DMV is your Problem...

California Drivers Advocates is your solution. We Are Here To Defend Your Driving Privilege. Contact our DMV Defense Experts here.