Probable Cause in DUI Cases
If you've been charged with a DUI in Tucson or anywhere in Pima County, you're likely feeling overwhelmed and uncertain about your next steps. One of the most important aspects of defending your case is challenging whether the police had probable cause to arrest you in the first place. As an experienced Tucson DUI defense attorney at AJB Law Firm, LLC, I’ve seen firsthand how officers often make assumptions that don't hold up under scrutiny. In fact, I recently won a motion to dismiss for lack of probable cause after carefully reviewing the evidence and highlighting inconsistencies in the officer's testimony.
What Is Probable Cause in a DUI Case?
Probable cause is a legal standard that requires law enforcement officers to have objective, reasonable grounds to believe that a crime has been committed before making an arrest. In DUI cases, this means that the officer must observe behaviors or obtain evidence that clearly indicates impairment. This might include things like:
Slurred speech
Bloodshot or watery eyes
The odor of alcohol
Unsteady or swaying movement
Poor performance on field sobriety tests (FSTs)
However, just because an officer claims to have observed these signs doesn’t mean they actually existed or indicated impairment. Officers are human—they can make mistakes, misinterpret behavior, or exaggerate observations. Even a trained officer's subjective interpretation of a situation can lead to wrongful arrests if not supported by reliable, objective evidence. That’s why it’s critical to challenge probable cause in every DUI case.
Why Challenging Probable Cause Is Critical
Challenging probable cause is essential because if it is shown that the officer lacked probable cause to make the arrest, the entire case can be dismissed. This means that any evidence gathered after the arrest—like breathalyzer results or blood tests—can be thrown out as well.
In a DUI case, police officers are trained to recognize specific signs of impairment, but human error and biases can still influence their observations. An officer may jump to conclusions based on limited evidence or preconceived notions, especially if the driver seems anxious or emotional during the stop. That’s why a critical part of a DUI defense is analyzing every detail of the stop and holding law enforcement accountable to legal standards.
Real-Life Example: Dismissed for Lack of Probable Cause
In a recent case I handled in Pima County, the arresting officer claimed that my client exhibited several signs of impairment, including slurred speech, swaying, and red, watery eyes. However, I obtained the body-worn camera footage from the traffic stop and carefully compared it to the officer’s testimony. Here’s what I found:
The client’s speech was clear and not slurred, despite the officer’s claim.
The video clearly showed no swaying during the interaction, even when my client was putting on her boots.
The officer noted red, watery eyes, but the footage showed her eyes appearing normal after removing her glasses.
The court agreed that the officer’s claims were not supported by objective evidence and ruled that there was no probable cause for the arrest, resulting in a dismissal of the charges. This outcome demonstrates the importance of challenging every element of the prosecution’s case and not taking the officer’s word at face value.
How Body-Worn Camera Footage Can Save Your Case
One of the most important tools in defending DUI cases is body-worn camera footage. This objective evidence often tells a different story than what is written in the police report or stated in court. In my case, it was the camera footage that ultimately proved my client’s innocence.
Body-worn camera footage can capture crucial details that contradict an officer’s testimony. In the heat of a traffic stop, officers may not accurately recall every detail or may unintentionally fill in gaps with assumptions. Reviewing the footage allows defense attorneys to pinpoint inconsistencies and highlight how stress or environmental conditions may have influenced an officer’s perception.
The Role of Field Sobriety Tests (FSTs) in Probable Cause
Field Sobriety Tests are often a key part of establishing probable cause, but they are far from foolproof. There are several problems with how FSTs are conducted and interpreted, especially under adverse conditions like:
Heavy traffic noise that makes it difficult to hear instructions.
Wind or rain that affects balance and coordination.
Poor lighting that impedes an officer’s ability to make accurate observations.
In my recent case, the field sobriety tests were conducted on a windy, rainy highway with cars whizzing by at 65 mph. The officer claimed that the client’s eyes were watering due to impairment, but the footage clearly showed that cold wind was blowing directly into her face. Moreover, the Horizontal Gaze Nystagmus (HGN) test was administered while vehicles moved in the subject’s peripheral vision—a direct violation of NHTSA guidelines.
When cross-examined, the officer admitted that moving objects could cause false positives for nystagmus, undermining his own assessment. This highlights how challenging the circumstances of the test can render the results invalid.
Why You Need an Experienced Tucson DUI Defense Attorney
The stakes are high in a DUI case, and your freedom, reputation, and future are on the line. You need an attorney who knows how to challenge the evidence and hold law enforcement accountable. I’m passionate about making sure my clients aren’t convicted based on faulty assumptions or unreliable observations.
