How Police Build DUI Cases: What Officers Look For and How We Fight Back

In Chicago, a night out can quickly spiral into a legal nightmare if you’re accused of driving under the influence. DUI arrests are not limited to repeat offenders. Every day, working professionals, students, and parents in neighborhoods from Lincoln Park to Englewood find themselves pulled over and facing charges that can follow them for life. But most drivers don’t realize that DUI cases are built on evidence that isn’t always as solid as it seems. Police must follow strict procedures, and much of the evidence they rely on can be challenged—if you have the right attorney.

At The Law Offices of David L. Freidberg, we understand how law enforcement gathers DUI evidence—and how to dismantle it.

What Starts a DUI Stop in Chicago?

Many DUI cases begin with a minor traffic infraction. It could be drifting over the lane divider, a broken taillight, or forgetting to signal. That small issue opens the door for a bigger investigation. Under Illinois law (625 ILCS 5/11-501), police must have probable cause to stop your vehicle. But once they make that stop, they will immediately start collecting information to determine whether alcohol or drugs may be involved.

The officer is observing everything: how you speak, whether your eyes are red, how you respond to questions. In some cases, officers exaggerate these signs to justify an arrest. And in busy areas like River North or the West Loop, the pressure to make DUI arrests is high—especially during weekends and holidays when patrols are increased.

The Tools Officers Use to Support a DUI Charge

Officers aren’t just relying on hunches. They are trained to follow a standard protocol to strengthen the case against you. Here’s what they’ll focus on:

Visual and Behavioral Indicators
Officers often note subjective signs like slurred speech, odor of alcohol, or fumbling with documents. But these observations can be misleading. Someone could be tired, anxious, or simply nervous under pressure.

Field Sobriety Tests (FSTs)
These tests are designed to measure balance, coordination, and the ability to follow directions. You’ve probably heard of them—the one-leg stand, the walk-and-turn, and the horizontal gaze nystagmus (eye test). But these aren’t always reliable. Uneven pavement, bad weather, or a medical condition can easily cause a person to “fail.”

Preliminary Breath Test (PBT)
This small handheld breathalyzer is used roadside to gauge blood alcohol content (BAC). It’s not as accurate as a station breathalyzer and isn’t admissible in court to prove guilt. Still, police use it to justify an arrest.

Chemical Testing (Breath, Blood, or Urine)
After the arrest, more formal testing occurs. Refusing the test can result in a license suspension under Illinois’s Implied Consent Law (625 ILCS 5/11-501.1), even if no DUI conviction follows.

Dashcam and Bodycam Video
Most Chicago police vehicles are equipped with video systems. If those videos show you walking normally or responding clearly, they may contradict the officer’s claims. That footage is one of the first things we request when preparing a defense.

For a deeper breakdown of DUI arrest evidence, see our insights here:
https://www.chicagocriminallawyerblog.com

What the Prosecutor Has to Prove in Court

To secure a conviction, prosecutors must prove beyond a reasonable doubt that:

You were in actual physical control of a motor vehicle, and
You were under the influence of alcohol or drugs, or had a BAC of 0.08 or higher.

But what qualifies as “actual physical control”? You don’t even need to be driving when the police arrive. If you’re sitting in the driver’s seat with the keys nearby, that can be enough. This broad interpretation is often used to pursue charges against people who were trying to sleep it off in their car rather than drive drunk.

As your attorneys, we challenge every element of the prosecution’s case. If their evidence falls short—even slightly—we push for dismissal, suppression of evidence, or a favorable plea.

Real Case Example: Officer Testimony vs. Video Evidence

We recently defended a client arrested after attending a Bulls game. The officer claimed our client was “unsteady” and failed all sobriety tests. But the bodycam video told a different story: clear speech, steady walking, and calm behavior. The video showed how the client complied with every request, contradicting the officer’s claims.

We filed a motion to suppress the arrest, arguing the officer lacked probable cause. The court agreed, and the entire case was dismissed.

This outcome was possible because we demanded video footage and knew how to use it to counter weak testimony.

The Fallout of a DUI Conviction in Illinois

A DUI isn’t just about license suspension. A conviction affects your career, finances, and freedom. Even a first offense carries up to a year in jail, a $2,500 fine, and loss of driving privileges. You may also be required to install a BAIID device at your expense.

If the DUI involved injury, was a repeat offense, or occurred while driving without a license or insurance, you could face felony charges under 625 ILCS 5/11-501(d). A felony DUI can result in years in prison and a permanent felony record.

You’ll also face indirect penalties—higher insurance rates, difficulty finding housing, and limited job opportunities.

Why a Chicago DUI Defense Attorney Makes the Difference

DUI cases move fast. The statutory summary suspension starts just 46 days after the arrest. That’s why you need an experienced attorney immediately to request a hearing and preserve your rights.

At every step—from the first court appearance to pretrial motions—we work to suppress evidence, challenge procedure, and negotiate outcomes that minimize or eliminate long-term damage. When the facts allow, we fight aggressively at trial.

For more information on your rights after a DUI arrest, visit:
https://www.chicagocriminallawyer.pro

Defense Strategies We Use in DUI Cases

Not every DUI defense is the same. Your strategy depends on how you were stopped, what testing occurred, and what the evidence shows.

Here are just a few legal arguments we’ve successfully used in court:

No Probable Cause for the traffic stop
Improper Testing Procedures, including faulty calibration or expired devices
Medical Conditions, like diabetes or neurological disorders, that can mimic intoxication
Rising BAC, where your alcohol level increased after driving but before testing

Even when the evidence seems overwhelming, we find angles prosecutors miss—and we use them to protect your freedom and your future.

FAQs About DUI Evidence in Chicago, Illinois

Can I challenge the results of a breath test in court?
Yes. Breath tests can be unreliable if the machine wasn’t maintained, the officer wasn’t certified, or your test was contaminated by external factors like mouthwash or medical conditions.

What if I passed the field tests but was still arrested?
Passing field sobriety tests doesn’t guarantee you won’t be arrested. Police can claim they still had enough evidence based on behavior or a preliminary breath test. That doesn’t mean the evidence will hold up in court.

Is video footage always available in DUI cases?
Not always. But in many Chicago DUI arrests, dashcam and bodycam video exist. It’s important your attorney obtains and reviews this footage right away, as it can be critical to your defense.

Can I get my DUI case dismissed if the officer lied?
If there’s proof the officer’s testimony conflicts with video or physical evidence, it can destroy the prosecution’s case. We use cross-examination and motions to expose contradictions and get unjust arrests thrown out.

What’s the difference between a misdemeanor and felony DUI in Illinois?
A misdemeanor DUI typically involves a first or second offense with no aggravating factors. A felony DUI can be charged if it’s your third offense, caused injury or death, involved a minor, or was committed while driving on a suspended license.

Talk to an Attorney Before You Talk to Police or Prosecutors

Every word you say after a DUI arrest can be used against you. Police are trained to ask questions that will trap you into making incriminating statements. Prosecutors are already building their case—don’t help them do it.

Before you speak to anyone, speak to a defense lawyer who knows how DUI evidence works and how to dismantle it in court. The Law Offices of David L. Freidberg offers 24/7 consultations and has decades of experience defending against DUI charges in Chicago and surrounding counties.

Call The Law Offices of David L. Freidberg Today

If you’re under investigation or facing charges, act now. The prosecution is already building a case. You deserve a defense that’s prepared to challenge the legality of every move law enforcement made.

Contact us today at (312) 560-7100 or toll-free at (800) 803-1442 for a free consultation. We’re available 24/7 to serve clients throughout Illinois, Cook County, DuPage County, Will County, and Lake County.

You don’t have to face this alone—we’re here to fight for you.