What Police Look for to Justify a DUI Stop in Chicago — And How to Fight It

In Chicago, being pulled over for suspected drunk or drugged driving can happen in seconds, but the legal consequences can follow you for years. What often starts with something as small as a missed signal or a wide right turn can quickly turn into a DUI investigation. Police officers in Illinois are trained to identify signs of impairment that allow them to initiate a stop under the legal standard of “reasonable suspicion.” But what they claim to observe and what the evidence shows don’t always align—and that’s where a skilled DUI defense attorney in Chicago can intervene.

At The Law Offices of David L. Freidberg, we have decades of courtroom experience defending people charged with DUI and other criminal offenses in Chicago and surrounding counties. If you were stopped based on supposed signs of impairment, you need to understand how those observations are used against you—and how they can be challenged in court.

Chicago Streets and Reasonable Suspicion: What Gives Officers the Right to Pull You Over?

Under Illinois law, police may stop a vehicle if they have reasonable suspicion that a traffic violation or criminal activity has occurred. Reasonable suspicion is a lower threshold than probable cause, but it must still be based on identifiable facts—not just a hunch. For example, in downtown Chicago or on the Kennedy Expressway, an officer might initiate a stop based on weaving between lanes, sudden braking, or inconsistent speed. These signs may be legal to observe, but they’re not always reliable indicators of intoxication.

Statutorily, DUI offenses in Illinois are governed by 625 ILCS 5/11-501. The first offense is typically a Class A misdemeanor, punishable by up to one year in jail and up to $2,500 in fines. But factors like a high blood alcohol concentration (BAC), having a child in the car, or causing an accident can elevate the charge to a felony, potentially resulting in years of prison time.

In urban settings like Chicago, where heavy traffic, potholes, and one-way streets are common, perfectly smooth driving isn’t always possible. Unfortunately, these conditions can be misinterpreted as signs of impairment. That’s why reviewing the dashcam and bodycam footage is one of the first steps in building a DUI defense.

Learn more about how we fight traffic stop cases at www.chicagocriminallawyer.pro, and review legal updates and case outcomes on our blog.

Behavior That May Trigger a Stop (Even When You’re Sober)

Drivers are often surprised to learn that they don’t need to be drunk to be pulled over for DUI suspicion. Officers frequently list the following behaviors in their reports as justifications for traffic stops:

• Failing to use a turn signal
• Driving under or over the speed limit
• Making wide or abrupt turns
• Following too closely
• Braking erratically
• Drifting between lanes
• Striking or brushing a curb

These actions, whether caused by distraction, road conditions, or unfamiliarity with the area, are often used as indicators of potential impairment. Once a stop is made, the investigation escalates quickly. Officers will note the driver’s speech, eye movement, response time, and the presence of any smells—alcohol, cannabis, or otherwise.

Illinois is not a zero-tolerance state for alcohol consumption and driving, but it is when it comes to certain drugs. Even a trace amount of cannabis (if not medically prescribed), cocaine, or another controlled substance in your blood can lead to a DUI arrest.

If the officer believes there is cause, they will ask you to step out of the vehicle to perform standardized field sobriety tests (SFSTs). These tests—such as the walk-and-turn and the one-leg stand—are highly subjective and often affected by weather, clothing, or medical conditions. Still, they are frequently cited in police reports as evidence of impairment.

What Happens After the Stop: From Investigation to Arrest

Once you’re out of the car, the officer will begin conducting field sobriety tests. You have the right to refuse these tests, and doing so may actually limit the amount of evidence the state can use against you. However, refusal may make the officer more likely to arrest you. If arrested, you’ll be taken to the station for a chemical test—usually a breathalyzer or a blood test.

Under Illinois’s implied consent law (625 ILCS 5/11-501.1), refusing a chemical test after arrest triggers a statutory summary suspension of your driver’s license—12 months for a first refusal, and up to three years for repeat offenders. If you submit to the test and fail (BAC over 0.08), the suspension is six months for a first offense.

This administrative suspension is separate from any criminal penalty and goes into effect 46 days after notice is served unless you request a hearing. This is one of the many reasons why time is critical. Hiring a DUI defense attorney quickly can help you fight the license suspension and the criminal charges.

How a DUI Conviction Affects You in Illinois

DUI convictions carry serious consequences. In Illinois, a first-time DUI conviction can lead to:

• Up to 364 days in jail
• Fines of up to $2,500
• License suspension or revocation
• Mandatory DUI education or treatment
• Court supervision, probation, or community service

Second and third offenses carry steeper penalties, including mandatory jail time and felony charges. Aggravated DUI—such as one involving an accident with injury or driving on a suspended license—can result in a Class 4, 3, or even Class 2 felony, with penalties ranging from one to seven years in prison.

But the damage doesn’t end with the sentence. A DUI conviction becomes part of your permanent criminal record. It can affect your ability to find work, apply for housing, maintain professional licenses, and travel abroad. Insurance rates may skyrocket, and in some cases, your vehicle may be impounded.

With so much at stake, it’s a mistake to go through the criminal justice system without a skilled defense attorney. At The Law Offices of David L. Freidberg, we fight to reduce or dismiss charges by targeting weaknesses in the state’s evidence, including the legality of the traffic stop itself.

Challenging the Stop: When the Officer Got It Wrong

One of the most effective DUI defense strategies is to challenge the traffic stop itself. If the officer didn’t have reasonable suspicion based on specific, articulable facts, then the stop—and all evidence gathered afterward—may be unconstitutional.

Let’s take a real case we handled for a Chicago client. The officer stopped our client at 11:45 p.m. on a Saturday for “touching the center line.” No swerving or illegal lane changes occurred. The dashcam showed the vehicle staying entirely within its lane. Yet the officer arrested our client after a roadside PBT and a failed field sobriety test.

We filed a motion to suppress the stop, and at the hearing, we cross-examined the officer about the basis for the initial traffic stop. After seeing the footage and hearing our argument, the judge agreed that there was no valid reason for the stop. All evidence was suppressed, and the DUI charge was dismissed.

This case highlights how quickly assumptions about impairment can spiral—and how essential it is to challenge the validity of the officer’s claims from the start.

Why Legal Help Is Essential from Day One

DUI law is complicated, and Chicago-area prosecutors are aggressive. Without an attorney, you risk waiving your rights, missing deadlines, or accepting plea deals that could have been avoided with proper defense strategy. A defense lawyer can analyze the evidence, question the officer’s observations, and evaluate whether the traffic stop meets legal standards under both state and federal law.

We represent clients in Cook County, DuPage County, Will County, and Lake County. We know the tactics officers use to justify stops and the procedures prosecutors follow to secure convictions. Whether it’s a misdemeanor DUI or an aggravated felony charge, we’re prepared to fight for your freedom.

Get the Legal Defense You Deserve

At The Law Offices of David L. Freidberg, we’ve helped thousands of clients beat DUI charges, keep their licenses, and protect their criminal records. We scrutinize every step of the arrest—from the initial stop to the final chemical test—and build a defense tailored to your unique case.

Call Now – The Law Offices of David L. Freidberg Is Ready to Help

If you’ve been charged with DUI in Chicago and have a medical condition that may have impacted your arrest or test results, call The Law Offices of David L. Freidberg for a free 24/7 consultation.

If you were arrested in Chicago for DUI, protect your future by contacting The Law Offices of David L. Freidberg. We have decades of experience handling DUI cases in Illinois. Our firm is available 24/7 to provide the legal defense you deserve.

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.