How Can Drivers Challenge DUI/DWI Evidence?

Facing a DUI or DWI charge can turn your life upside down overnight. You may be scared, embarrassed, or unsure of what happens next. I've spoken with many clients who thought there was no way to fight the charge—especially if they blew over the legal limit or failed a field sobriety test. 

But DUI cases aren't always as open-and-shut as they seem. In fact, there are often several ways to challenge the evidence and fight back.

Challenging the evidence isn’t about finding a loophole—it’s about making sure the police and prosecution followed the law and respected your rights. Here, we'll discuss how drivers can challenge DUI evidence in Florida. Contact me, Attorney Stacey Marquez Esq., to get help with your defense.

Is It Really Possible to Challenge DUI Evidence?

Just because you were arrested doesn’t mean you’re guilty. In Florida, the prosecution has to prove your guilt beyond a reasonable doubt—and they rely heavily on evidence collected during and after the traffic stop. But that evidence is only as strong as the procedures used to obtain it.

Challenging the evidence can lead to reduced charges, a dismissed case, or even a full acquittal. That’s why the first step I take in every DUI case is to examine the evidence closely, piece by piece, to look for weaknesses that can work in your favor.

Questioning the Legality of the Traffic Stop

Police must have a valid reason—called "reasonable suspicion"—to pull you over. If they didn’t, any evidence collected after the stop may be thrown out.

Traffic stop challenges may include:

• Lack of probable cause: If you weren’t swerving, speeding, or violating any traffic laws, the stop may not have been legal.

• Pretextual stops: Officers can’t stop you based on a hunch or stereotype.

• Failure to observe your rights: If your rights were violated during the stop or arrest, I may be able to suppress key evidence.

• No clear signs of impairment: Video footage or witness testimony showing you appeared sober can help undermine the officer’s justification.

If the stop wasn’t legal, anything that happened afterward—field tests, breath tests, or arrests—could be ruled inadmissible. This alone can result in the entire case being dismissed.

Challenging Field Sobriety Tests

Field sobriety tests are designed to detect impairment, but they’re highly subjective and often flawed. Many factors can influence the outcome that have nothing to do with alcohol or drugs.

Issues with field sobriety tests may include:

• Poor instructions or demonstrations: If the officer didn’t explain the test properly, your performance can’t be fairly judged.

• Medical or physical conditions: Back pain, anxiety, fatigue, or inner ear issues can make tests hard to perform—even sober.

• Unfair testing conditions: Wet pavement, poor lighting, or uneven surfaces can cause anyone to stumble or lose balance.

• Officer bias: If the officer made assumptions based on appearance, attitude, or nervousness, their judgment may not be reliable.

Field sobriety tests aren't scientific. I often argue that they’re too unreliable to be used as evidence of impairment.

Disputing Breathalyzer and Blood Test Results

Many DUI cases rely on breath or blood test results to show a driver’s blood alcohol concentration (BAC). But even these "scientific" results can be challenged.

Common challenges to chemical test results include:

• Improper calibration or maintenance: Breathalyzer devices must be routinely maintained. If records show it wasn’t calibrated correctly, the results may not hold up.

• Operator error: The person administering the test must be trained and certified. If they weren’t, the test could be invalid.

• Mouth alcohol contamination: If you recently used mouthwash, coughed, vomited, or had dental work, your BAC reading may be artificially high.

• Delay in testing: BAC levels can rise over time. If the test was done long after the stop, it may not reflect your actual level while driving.

• Chain of custody issues (blood tests): Blood samples must be properly collected, labeled, and stored. Any gap or error in that process can lead to contamination or dismissal.

Breath and blood test results aren't immune to scrutiny. I often request calibration logs, maintenance records, and training certificates to challenge their accuracy.

Examining the Arrest Process and Police Conduct

Police officers must follow strict procedures during a DUI arrest. Any misstep can compromise the case.

Procedural issues that may help your defense include:

• Failure to read Miranda rights: If the officer didn’t inform you of your rights after arrest, your statements may be inadmissible.

• Coercive questioning: If you were pressured or intimidated into making a statement, I can argue to suppress that evidence.

• Unlawful search or seizure: Officers need a valid reason to search your car or person. If they didn’t have one, anything they found may not be allowed in court.

• Bias or discrimination: Any evidence that you were treated unfairly due to race, age, or other factors can raise constitutional concerns.

Even if the BAC reading seems high, police misconduct can give you a strong defense.

Presenting Alternative Explanations for Behavior

Sometimes the evidence looks bad on paper—but there’s a perfectly reasonable explanation. I work closely with clients to uncover facts the police may have overlooked.

Examples of alternative explanations include:

• Fatigue or illness: Drowsiness or a medical condition can mimic signs of impairment.

• Anxiety or nerves: Many people perform poorly on field tests due to stress, not alcohol.

• Allergies or medications: Certain medications or health conditions can affect your speech, balance, or appearance.

• Environmental factors: Bright lights, cold weather, or uneven pavement can influence test performance or officer observations.

Explaining your behavior clearly and logically can shift the narrative in your favor and create reasonable doubt.

Florida DUI Court Process and What to Expect

If you're charged with DUI in Florida, there are specific steps your case will follow. Being informed helps you prepare and feel more in control.

Stages of a Florida DUI case typically involve:

• Traffic stop and arrest: The officer must document their reason for stopping and arresting you.

• Booking and release: You may be released on bail or your own recognizance, depending on the circumstances.

• DMV hearing (license suspension): You have 10 days to request a hearing to contest your license suspension.

• Arraignment: You’ll enter a plea—usually not guilty—while I begin reviewing the evidence.

• Pretrial motions: This is when I’ll challenge evidence and potentially negotiate for reduced charges.

• Trial or resolution: If no plea is accepted, the case goes to trial, where a judge or jury decides your guilt or innocence.

Throughout the process, I’ll help you understand your rights, keep you informed, and fight for the best possible outcome.

Contact a Trusted DUI Defense Lawyer

From questioning the traffic stop to analyzing breath test data, every detail matters when it comes to your DUI defense.

At Marquez Law, I represent clients in Orlando and West Palm Beach, Florida, and throughout Orange County, Osceola County, Seminole County, Palm Beach County, and Broward County, who are facing drunk driving charges. 

I’ll listen to your story, dig into the evidence, and work relentlessly to protect your license, your record, and your future. Reach out to my firm today to schedule a consultation with a skilled criminal defense lawyer.