Can Police Arrest You for DUI if Your BAC Is Below 0.08 in Illinois?

 Posted on August 14, 2026 in DUI

Police can arrest you for driving under the influence (DUI) in Illinois even if your blood alcohol concentration is below 0.08. Illinois law allows a DUI arrest based on observable signs of impairment noticed by the arresting officer. This is true regardless of the specific number your breath or blood test shows. However, you will still have the chance to fight the charge.

If you've been arrested for DUI in 2026 with a BAC below this level, our Naperville DUI defense lawyer can help you understand your options. Attorney Phil Nathe brings over 25 years of legal experience to these cases. Talk to him about the details of your case.

How Does Illinois Law Define DUI Beyond the 0.08 Threshold?

Under 625 ILCS 5/11-501, a person can be charged with DUI in Illinois for driving while under the influence of alcohol, even if their BAC is below 0.08. A BAC of 0.08 or higher is one way to establish a DUI violation, but it is not the only way.

An officer who observes signs of impairment can arrest and charge you with DUI even if a later test shows your BAC below 0.08. Signs may include slurred speech, poor coordination, or erratic driving.

Illinois law also provides that a BAC of 0.05 or less creates a presumption that the person was not under the influence. A BAC above 0.05 but below 0.08 creates no presumption either way and may be considered along with other evidence.

Why Does Illinois Allow This Below-Threshold DUI Standard?

Alcohol affects people differently based on factors like body weight, tolerance, and how much food they've eaten. Someone with a lower tolerance might show clear signs of impairment at a BAC well below 0.08. Another person might show fewer outward signs at a higher level. This is why Illinois law allows prosecution based on observed impairment rather than relying exclusively on a specific numerical threshold.

What Evidence Do Police Use to Support a Below-0.08 DUI Charge?

Police and prosecutors typically build their case using other forms of evidence, since these cases don't rely on a BAC reading meeting the standard threshold. Common evidence includes field sobriety test performance and the officer's observations of your driving pattern before the stop. Your behavior and speech during the traffic stop itself also matter.

Officers often document specific details like watery or bloodshot eyes, the smell of alcohol, and any admissions you made about drinking. All of these can be used to support a charge even without a BAC result at or above 0.08.

How Reliable Are Field Sobriety Tests in These DUI Cases?

Field sobriety tests are subjective. They can be affected by factors unrelated to alcohol impairment. Fatigue, nervousness, medical conditions, or uneven road surfaces during roadside testing can all affect how you perform. This subjectivity often becomes a central point of challenge in below-threshold DUI cases. That’s because these tests carry significant weight when there's no clear BAC number to rely on.

What Defenses Are Available in a Below-0.08 DUI Case?

Several defense strategies can apply in cases where the BAC was below 0.08. Common defenses include:

• Challenging the officer's subjective observations of impairment
• Questioning whether field sobriety tests were conducted properly
• Presenting evidence of medical conditions that might explain observed behaviors
• Arguing that the traffic stop itself wasn't legally justified
• Highlighting inconsistencies between the officer's report and other available evidence, such as dashcam footage

A thorough review of all available evidence can reveal significant weaknesses in the prosecution's case. These cases often come down to subjective observations rather than a hard number.

Why Are Below-0.08 DUI Cases Often More Difficult for Prosecutors?

Prosecutors must rely more heavily on subjective evidence without a BAC reading at or above the legal threshold. Juries and judges may view this evidence with more skepticism than a clear numerical test result. This can create meaningful opportunities for a defense attorney to challenge the strength of the state's case.

This doesn't mean these charges are easy to defeat. Officer testimony and field sobriety test results can still be compelling if presented effectively. There's often more room to challenge the evidence than in a straightforward case involving a BAC above 0.08, though.

Contact Our Naperville, IL DUI Defense Attorney for a Free Consultation

Attorney Nathe is a former Assistant State's Attorney for DuPage County. This gives him valuable insight into how these cases are built and prosecuted from the other side. This perspective allows him to identify weaknesses in the state's evidence that might not be obvious to attorneys without prosecutorial experience.

Contact The Law Office of Philip R. Nathe at 630-416-7600 to talk to our Naperville DUI defense lawyer today.